Growth and Yield Performance of Selected Wheat Genotypes at Variable Irrigation Management

Authors

• Md. Abdur Rahman, Shamima Akter Bely, Mst. Afrose Jahan, A. T. Shamsuddoha 1Department of Soil Science, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh.
• Sonia Nusrin 2Department of Development and Poverty Studies, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh.
• Sifat Jahan, Md. Saiful Islam* 3Department of Agricultural Extension and Information System, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh.

Abstract

The experiment was conducted in the Agronomy Field, Sher-e-Bangla Agricultural University (SAU), Dhaka-1207 during the period of November 17, 2016 to March 29, 2017 on growth and yield performance of selected wheat genotypes at variable irrigation. In this experiment, the treatment consisted of three varieties viz. V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30, and four different irrigations viz. I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages). The experiment was laid out in two factors split plot with three replications. The collected data were statistically analyzed for evaluation of the treatment effect. Results showed that a significant variation among the treatments in respect majority of the observed parameters. Results showed significant variation in almost every parameter of treatments. The highest Plant height, number of effective tillers hill^-1, spike length, number of grain spike^-1 was obtained from BARI Gom-30. The highest grain weight hectare^-1 (3.44 ton) was found from wheat variety BARI Gom-30. All parameters of wheat showed statistically significant variation due to variation of irrigation. The maximum value of growth, yield contributing characters, seed yield was observed with three irrigation (irrigate at CRI, booting and grain filling stages). The interaction between different levels of variety and irrigation was significantly influenced on almost all growth and yield contributing characters, seed yield. The highest yield (3.99 t ha^-1) was obtained from BARI Gom-30 with three irrigation (irrigate at CRI, booting and grain filling stages). The optimum growth and higher yield of wheat cv. BARI Gom-30 could be obtained by applying three irrigations at CRI, booting and grain filling stages.

Introduction

Wheat (Triticumaestivum L.) is one of the most important cereal crops cultivated all over the world. Wheat production was increased from 585,691 thousand tons in 2000 to 713,183 thousand tons in 2013 which was ranked below rice and maize in case of production (FAO, 2015). In the developing world, need for wheat will be increased 60 % by 2050 (Rosegrant and Agcaoili, 2010). The International Food Policy Research Institute projections revealed that world demand for wheat will increase from 552 million tons in 1993 to 775 million tons by 2020 (Rosegrantet al.,1997).  Wheat grain is the main staple food for about two third of the total population of the world. (Hanson et al., 1982).

It supplies more nutrients compared with other food crops. Wheat grain is rich in food value containing 12% protein, 1.72% fat, 69.60% carbohydrate and 27.20% minerals (BARI, 2006). It is the second most important cereal crop after rice in Bangladesh.  So, it is imperative to increase the production of wheat to meet the food requirement of vast population of Bangladesh that will secure food security. During 2013-14 the cultivated area of wheat was 429607 ha having a total production of 1302998 metric tons with an average yield of 3.033 metric tons ha^-1whereas during 2012-13 the cultivated area of wheat was 416522 ha having a total production of 1254778 metric tons with an average yield of 3.013 tons ha^-1 (BBS, 2014).

Current demand of wheat in the country is 3.0-3.5 million tons.  Increasing rate of consumption of wheat is 3% per year (BBS, 2013). Wheat production is about 1.0 milllion from 0.40 million hectares of land. Bangladesh has to import about 2.0-2.5-million-ton wheat every year. Wheat is grown all over Bangladesh but wheat grows more in Dhaka, Faridpur, Mymensingh, Rangpur, Dinajpur, Comilla districts. Wheat has the umpteen potentialities in yield among other crops grown in Bangladesh.  However, yield per hectare of wheat in Bangladesh is lower than other wheat growing countries in the world due to various problems.  

Increasing food production of the country in the next 20 years to much population growth is a big challenge in Bangladesh. It is more difficult because, land area devoted to agriculture will decline and better-quality land and water resources will be divided to the other sector of national economy.  In order to grow more food from marginal and good quality lands, the quality of natural resources like seed, water, varieties and fuel must be improved and sustained. Variety plays an important role in producing high yield of wheat because different varieties responded differently for their genotypic characters, input requirement, growth process and the prevailing environment during growing season.

In Bangladesh the wheat growing season (November-March) is in the driest period of the year.  Wheat yield was declined by 50% owing to soil moisture stress. Irrigation water should be applied   in different critical stages of wheat for successful wheat production. Shoot dry weight, number of grains, grain yield, biological yield and harvest index decreased to a greater extent when water stress was imposed at the anthesis stage while water stress was imposed at booting stage caused a greater reduction in plant height and number of tillers (Gupta et al., 2001). Determination of accurate amount of water reduces irrigation cost as well as checks ground water waste. Water requirements vary depending on the stages of development. The pick requirement is at crown root initiation stage (CRI). In wheat, irrigation has been recommended at CRI, flowering and grain filling stages. However, the amount of irrigation water is shrinking day by day in Bangladesh which may be attributed to filling of pond river bottom. Moreover, global climate change scenarios are also responsible for their scarcity of irrigation water. So, it is essential to estimate water saving technique to have an economic estimate of irrigation water.

Information on the amount of irrigation water as well as the precise sowing time of wheat with change in climate to expedite wheat production within the farmer’s limited resources is inadequate in Bangladesh. The need of water requirement also varies with sowing times as the soil moisture depletes with the days after sowing in Bangladesh as there is scanty rainfall after sowing season of wheat in general in the month of November.

With above considerations, the present research work was conducted with the following objectives:

1. To evaluate yield performance of selected wheat genotypes(s) at variable irrigation management.
2. To identify the suitable genotype (s) of wheat giving higher yield under moisture stress condition.

 Materials and Methods

Description of the experimental site

The experiment was conducted in the Research Field, Sher-e-Bangla Agricultural University (SAU), Dhaka-1207 during the period of November, 2016 to March, 2017 to observe the growth and yield performance of selected wheat genotypes at variable irrigation management. The experimental field is located at 23041´ N latitude and 90º 22´ E longitude at a height of 8.6 m above the sea level belonging to the Agro-ecological Zone “AEZ-28” of Madhupur Tract (BBS, 2013).

Soil characteristics

The soil of the research field is slightly acidic in reaction with low organic matter content. The selected plot was above flood level and sufficient sunshine was available having available irrigation and drainage system during the experimental period. Soil samples from 0-15 cm depths were collected from experimental field. The experimental plot was also high land, having pH 5.56.

Climate condition

The experimental field was situated under sub-tropical climate; usually the rainfall is heavy during Kharifseason, (April to September) and scanty in Rabi season (October to March). In Rabi season temperature is generally low and there is plenty of sunshine. The temperature tends to increase from February as the season proceeds towards kharif. Rainfall was almost nil during the period from November 2016 to March 2017 and scanty from February to September.

Planting material

The test crop was wheat (Triticumaestivum). Three wheat varieties BARI Gom-26, BARI Gom-28 and BARI Gom-30 were used as test crop and were collected from Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur.

Treatments

The experiment consisted of two factors and those were the wheat genotypes and irrigation. Three wheat genotypes and four irrigations were used under the present study. Factor A: three wheat varieties- V₁ = BARI Gom-26, V₂ = BARI Gom-28 and V₃= BARI Gom-30. Factor B: four irrigations- I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling) and I₃= Three irrigation (Irrigate at CRI, booting and grain filling stages). The experiment was laid out in a split plot design with three replications having irrigation application in the main plots, verities in the sub plots. There were 12 treatments combinations. The total numbers of unit plots were 36. The size of unit plot was 2 m x 2 m = 4.00 m². The distances between sub-plot to sub-plot, main plot to main plot and replication to replication were, 0.75, 0.75 and 1.5 m, respectively.

 Statistical analysis

The collected data on each plot were statistically analyzed to obtain the level of significance using the computer-based software MSTAT-C developed by Gomez and Gomez, 1984. Mean difference among the treatments were tested with the least significant difference (LSD) test at 5 % level of significance.

Results and Discussion

Plant height

Plant height varied significantly among the tested three varieties (Table 1). At, 75 DAS, BARI Gom 30 showed the tallest plant height (34.72 cm) and BARI Gom 26 recorded the shortest plant height (32.32 cm). At, 90 DAS, BARI Gom 30 recorded the highest plant height (76.13 cm) was observed from BARI Gom 26. However, BARI Gom 26 recorded the shortest plant height (75.01 cm) which was also statistically similar with BARI Gom 28. Islam and Jahiruddin (2008) also concluded that plant height varied significantly due to various wheat varieties. Plant height of wheat showed statistically significant variation due to amount of irrigation at 75, 90 DAS under the present trial (Table 2). At 75 DAS, the tallest plant (34.78 cm) was recorded from I₃ (Three irrigation) while the shortest plant (32.02 cm) was observed from I₀ (No Irrigation throughout the growing season) treatment. At 60 DAS, the tallest plant (77.51 cm) was found from I₃, which was statistically similar with I₂ (Two irrigation) and I₁ (One irrigation).  The shortest plant (71.29 cm) was observed from I₀. Plant height was likely increased due to applying higher amount of irrigation compared to less amount of irrigation. Sultana (2013) stated that increasing water stress declined the plant height. Interaction effect of variety and different amount of irrigation showed significant differences on plant height of wheat at 75 and 90 DAS (Table 3). The highest plant height at 30 was 38.00 cm obtained from V₃I₃ treatment combination. The shortest plant height at 30 was 30.67 cm obtained from V₁I₀ treatment combination. At 60 DAS, plant height was 78.50 cm obtained from V₃I₃ and lowest was 69.83 cm obtained from V₁I₀ treatment combination, which was statistically similar with V₂I₀ and ₃I₀ treatment combination. 

Table 1. Effect of variety on plant height of wheat at different days after sowing

Table 2. Effect of irrigation on plant height of wheat at different days after sowing

Table 3. Interaction effect of variety and irrigation on plant height of wheat

Number of effective tiller hill^-1

Number of effective tillers hill^-1of wheat was not varied significantly due to varieties (Table 4). BARI Gom 30 produced the highest number of effective tillers hill^-1 (9.33) and the lowest number of effective tillers hill^-1(8.58) was observed in BARI Gom 26. Different levels of irrigation varied significantly in terms of number of effective tillers hill^-1 of wheat at harvest under the present trial (Table 5). The highest number of effective tillers hill^-1 9.89 was recorded from I₃ treatment, while the corresponding lowest number of effective tillers hill^-1 were 7.89 observed in I₀ treatment. Sultana (2013) stated that increasing water stress reduced the number of tillers per hill. Variety and irrigation showed significant differences on number of effective tillers hill^-1 of wheat due to interaction effect (Table 6). The highest number of effective tillers hill^-1 10.33 were observed from V₃I₃ treatment combination, while the corresponding lowest number of effective tillers hill^-1 as 7.33 were recorded from V₁I₀ treatment combination. 

Number of non-effective tiller hill^-1

Number of non-effective tillers hill^-1of wheat was not varied significantly due to varieties (Table 4). BARI Gom 26 produced the highest number of non-effective tillers hill^-1 (1.33) and the lowest number of non-effective tillers hill^-1(1.00) was observed in BARI Gom 30. Different levels of irrigation varied significantly in terms of number of non-effective tillers hill^-1 of wheat at harvest under the present trial (Table 5). The highest number of non-effective tillers hill^-1 (2.00) was recorded from I₀, while the corresponding lowest number of non-effective tillers hill^-1 (0.67) was observed in I₃. Variety and irrigation showed significant differences on number of non-effective tillers hill^-1 of wheat due to interaction effect (Table 6). The highest number of non-effective tillers hill^-1 (2.33) were observed from V₁I₀ treatment combination, while the corresponding lowest number of non-effective tillers hill^-1 (0.33) were recorded from V₃I₂ treatment combination.

Table 4. Effect of variety on yield and yield contributing characters of wheat

Table 5. Effect of irrigation on yield and yield contributing characters of wheat

Table 6. Interaction effect of variety and irrigation on yield and yield   contributing characters of wheat

Spike length (cm)

Insignificant variation was observed on spike length (cm) at applied three types of modern wheat variety as BARI Gom-26 (V₁), BARI Gom-28 (V₂), and BARI Gom-30 (V₃). From the experiment with that three types of varieties BARI Gom-30 (V₃) (8.46 cm) given the largest spike length and BARI Gom-26 (V₁) (8.08 cm) was given the lowest spike length (Table 4). Similar result was found using with different type varieties by Hefniet al. (2000). Different irrigation application has a statistically significant variation on spike length as irrigated condition (I₃) was given the maximum result (9.17 cm) and non-irrigated condition (I₀) given the lowest spike length (7.17 cm) (Table 5). Interaction effect of improved wheat variety and irrigation showed significant differences on spike length. Results showed that the highest spike length was obtained from V₃I₃ (10.33 cm). On the other hand, the lowest spike length was observed at V₁I₀ (6.50cm) treatment combination (Table 6).

 Grain spike^-1

Significant variation was observed on grain spike^-1 at these applied three types of modern wheat variety. The BARI Gom-30 (V₃) (37.75) given the maximum number of grain spike^-1 and BARI Gom-26 (V₁) (36.92) was given the lowest number of grain spike^-1, which was statistically similar with V₂ treatment (Table 4). Different wheat genotypes have significant effect on grain spike^-1 observed also by Rahman et al. (2009). Different irrigation application has a statistically significant variation on grain spike^-1 as the irrigation condition (I₃) was given the maximum result (39.33), which was statistically similar with I₂ and non-irrigated condition (I₀) given the lowest grain spike^-1 (34.56) (Table 5). Sarkar et al. (2010) also observed that irrigation have a significant effect on grain spike^-1. Interaction effect of improved wheat variety and irrigation showed significant differences on grain spike^-1. Results showed that the highest grain spike^-1 was obtained from V₃I₃ (41.0). On the other hand, the lowest grain spike^-1 was observed at V₁I_o (34.00) which were also statistically similar with V₃Io (34.67) (Table 6).

3Thousand Seed weight

There was significant variation was observed on thousand seed weight due to different types of modern wheat variety. The wheat variety of BARI Gom-30 (V₃) (50.40 g) given the maximum thousand seed weight and statistically different from BARI Gom-28 (V₂) (46.74 g). BARI Gom-26 (V₁) (46.22 g) was given the lowest thousand seed weight (Table 7). Rahman et al. (2009), Islam et al. (2015) also conducted experiment with different variety and observed have effect of varieties on yield. Different irrigation application has a statistically significant variation on thousand seed weight. The I₃ was given the maximum thousand seed weight (48.91) and non-irrigated condition (I₀) given the lowest yield (46.13 g) (Table 8). Sarkar et al. (2010), Baser et al. (2004) reported that grain yield under non-irrigated conditions was reduced by approximately 40%. Bazzaet al. (1999) reported that one water application during the tillering stage allowed the yield to be lower only than that of the treatment with three irrigations but Meenaet al. (1998) reported that wheat grain yield was the highest with 2 irrigations (2.57 ton/ha in 1993 and 2.64 ton/ha) at flowering and/or crown root initiation stages. Wheat is sown in November to ensure optimal crop growth and avoid high temperature and after that if wheat is sown in the field it faces high range of temperature for its growth and development as well as yield potential. Islam et al. (2015) reported that late planted wheat plants faced a period of high temperature stress during reproductive stages causing reduced kernel number spike^-1 as well as the reduction of grain yield. Interaction effect of improved wheat variety and irrigation showed significant differences on thousand seed weight (Table 9). Results showed that the highest thousand seed weight (52.33 g) was obtained from V₃I₃ which was statistically similar with V₃I₂ (52.06 g). On the other hand, the lowest yield (45.36 g) was observed at V₁I₁.

Table 7. Effect of variety on yield and yield of wheat

Table 8. Effect of irrigation on yield and yield of wheat

Table 9. Interaction effect of variety and irrigation on yield and yield of wheat

Grain yield (t ha^-1)

Different wheat varieties showed significant difference for grain weight hectare^-1 (Table 7). The highest grain yield hectare^-1 (3.44 ton) was found from wheat variety BARI Gom-30 (V₃), which was statistically similar with V₂, whereas the lowest (3.21 ton) was observed from wheat variety BARI gom 26. Rahman et al. (2009), Islam et al. (2015) also conducted experiment with different variety and observed have effect of varieties on yield. Significant difference was observed for yield for different irrigation application. The three irrigation (I₃) was given the maximum yield (3.74 t ha^-1), which was statistically similar with I₂ treatment and non-irrigated condition (I₀) given the lowest yield (2.97 t ha^-1) (Table 8). Sarkar et al. (2010), Baser et al. (2004) reported that grain yield under non-irrigated conditions was reduced by approximately 40%. Bazzaet al. (1999) reported that one water application during the tillering stage allowed the yield to be lower only than that of the treatment with three irrigations but Meenaet al. (1998) reported that wheat grain yield was the highest with 2 irrigations (2.57 ton/ha in 1993 and 2.64 ton/ha) at flowering and/or crown root initiation stages. Wheat is sown in November to ensure optimal crop growth and avoid high temperature and after that if wheat is sown in the field it faces high range of temperature for its growth and development as well as yield potential. Islam et al. (2015) reported that late planted wheat plants faced a period of high temperature stress during reproductive stages causing reduced kernel number spike^-1 as well as the reduction of grain yield. Interaction effect of improved wheat variety and irrigation showed significant differences on yield (t ha^-1). Results showed that the highest yield (3.99 t ha^-1) was obtained from V₃I₃, which was statistically similar with V₂I₃ and V₃I₂. On the other hand, the lowest yield (2.93 t ha^-1) was observed at V₁I₀ (Table 7).

 Straw yield (t ha^-1)

Applied three types of wheat variety have a statistically significant variation on straw yield (t ha^-1). The maximum straw yield (1.95 t ha^-1) was obtained from BARI Gom-30 and BARI Gom-26 (V₁) was given the lowest straw yield (1.87 t ha^-1), which was statistically similar with V₂ treatment. Different irrigation application has a statistically significant variation on straw yield (t ha^-1) of wheat.  The I₃ treatment for straw yield (2.01 t ha^-1) was given the maximum result and non-irrigated condition (I₀) given the lowest (1.80 t ha^-1). Similar results were found by Ali and Amin (2004) through his experiment. Interaction effect of improved wheat variety and irrigation showed significant differences on straw yield (t ha^-1). The highest straw yield (2.08 t ha^-1) was obtained from V₃I₃ which was statistically similar with V₃I₂ (2.07 t ha^-1) treatment combination. On the other hand, the lowest straw yield (1.78 t ha^-1) was observed at V₁Io, which was statistically similar with V₂I₀ (2.07 t ha^-1) treatment combination.

Biological yield

Significant variation was attained for biological yield for different wheat varieties. The variety BARI Gom-30 given the maximum biological yield (5.39 t ha^-1) and BARI Gom-26 (V₁) was given the lowest biological yield (5.078 t ha^-1). Different irrigation application has a statistically significant variation biological yield (t ha^-1) of wheat.  The I₃ treatment for biological yield (5.76 t ha^-1) was given the maximum result and non-irrigated condition (I₀) given the lowest (4.77 t ha^-1). Similar results were found by Ali and Amin (2004) through his experiment. At the time of biological yield (t ha^-1) consideration with variety and irrigation statistically significance variation was observed as maximum biological yield (t ha^-1) at V₃I₃ (6.07 t ha^-1). On the other hand, the lowest result was given at V₁Io (4.72 tha^-1).

Summary And Conclusion

It may be concluded within the scope and limitation of the present study that the optimum growth and higher yield of wheat cv. BARI Gom-30 could be obtained by applying three irrigations at irrigate at CRI, booting and grain filling stages. However, further studies are necessary to arrive at a definite conclusion.

References

1. Ali, M. N.; and Amin, M.S. Effect of single irrigation and sowing date on growth and yield of wheat. M. S. thesis, SAU, Dhaka, Bangladesh. 2004.
2. (Bangladesh Agricultural Research Institute). Hand book of Agricultural Technology. Joydebpur, Gazipur. 2006, 9.
3. Baser, I.; Sehirali, S.; Orta, H.; Erdem, T.; Erdem, Y.; Yorganclar, O. Effect of different water stresses on the yield and yield components of winter wheat. Cereal Res. Comn. 2004, 32(2), 217-223.
4. Bazza, S. S.; Awasthi, M. K.; Nema, R. K. Studies on Water Productivity and Yields Responses of Wheat Based on Drip Irrigation Systems in Clay Loam Soil. Indian J. Sci. Tech. 1999, 8(7), 650-654.
5. Bangladesh Bureau of Statistics, Ministry of Planning, Government of the Peoples Republic of Bangladesh, Dhaka. 2013.
6. Bangladesh Bureau of Statistics, Ministry of Planning, Government of the Peoples Republic of Bangladesh, Dhaka. 2014.
7. K. A.; Gomez, A. A. Statistical Procedures for Agricultural Research. 2nd edition. John Willy and Sons, New York. 1984, 28-192.
8. Gupta, P. K.; Gautam, R. C.; Ramesh, C. R. Effect of water stress on different stages of wheat cultivation. Plant Nutri. and Fert. Sci. 2001, 7(2), 33-37.
9. Hanson, M.; Farooq, M.; Shabir, G.; Khan, M. B.; Zia, A. B.; Lee, D. G. Effect of date sowing and rate of fertilizers on the yield of wheat under irrigated condition. J. Agril. & Biol. 1982, 14(4), 25-31.
10. Hefni, S.; Sajjad, A.; Hussain M. I.; Saleem, M. Growth and yield response of three wheat varieties to different seeding densities. J. Agric. Biol. 2000, 3(2), 228-229.
11. Islam, S.; Islam, S.; Uddin, M. J.; Mehraj, H.; Jamal Uddin, A. F. M. Growth and yield response of wheat to irrigation at different growing stages. J. Agron. Agril. Res. 2015, 6(1), 70-76.
12. Meena, B. N.; Tunio, S. D.; Shah, S. Q. A.; Sial, M. A.; Abro, S. A. Studies on grain and grain yield associated traits of bread wheat (Triticum aestivum L.) varieties under water stress conditions. Pakistan J. Agril. Engin. Vet. Sci. 1998, 24(2), 5-9.
13. Rahman, M. ; Hossain, A.; Hakim, M. A.; Kabir, M.  R; Shah, M. M. R. Performance of wheat genotypes under optimum and late sowing condition.  Int.  J. Sustain Crop Prod. 2009, 4(6), 34-39.
14. Rosegrant, M. W.; Agcaoili, M. Global food demand, supply, and price prospects to 2010. Washington, DC: Int. Food Policy Res. Inst. 2010.
15. Rosegrant, M. W.; Sombilla, M. A.; Gerpacio R. V.; Ringler, C. Global food markets and US exports in the twenty-first century. Paper prepared for the Illinois World Food and Sustainable Agriculture Program Conference ‘Meeting the Demand for Food in the 21st Century: Challenges and Opportunities for Illinois Agriculture’, 1997.
16. Sarker, S.; Singh, S. K.; Singh, S. R.; Singh, A. P. Influence of initial profile water status and nitrogen doses on yield and evapotranspiration rate of dryland barley. Indian Soc. Soil Sci. 2010, 47(1), 22-28.
17. Sultana, F. Effect of irrigation on yield and water use of wheat. M.S. Thesis, Dept. of Irrigation and Water Management. Bangladesh Agril. Univ., Mymensingh. 2013.

Abstract

The experiment was conducted in the Agronomy Field, Sher-e-Bangla Agricultural University (SAU), Dhaka-1207 during the period of November 17, 2016 to March 29, 2017 on growth and yield performance of selected wheat genotypes at variable irrigation. In this experiment, the treatment consisted of three varieties viz. V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30, and four different irrigations viz. I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages). The experiment was laid out in two factors split plot with three replications. The collected data were statistically analyzed for evaluation of the treatment effect. Results showed that a significant variation among the treatments in respect majority of the observed parameters. Results showed significant variation in almost every parameter of treatments. The highest Plant height, number of effective tillers hill^-1, spike length, number of grain spike^-1 was obtained from BARI Gom-30. The highest grain weight hectare^-1 (3.44 ton) was found from wheat variety BARI Gom-30. All parameters of wheat showed statistically significant variation due to variation of irrigation. The maximum value of growth, yield contributing characters, seed yield was observed with three irrigation (irrigate at CRI, booting and grain filling stages). The interaction between different levels of variety and irrigation was significantly influenced on almost all growth and yield contributing characters, seed yield. The highest yield (3.99 t ha^-1) was obtained from BARI Gom-30 with three irrigation (irrigate at CRI, booting and grain filling stages). The optimum growth and higher yield of wheat cv. BARI Gom-30 could be obtained by applying three irrigations at CRI, booting and grain filling stages.

1. Introduction

Wheat (Triticumaestivum L.) is one of the most important cereal crops cultivated all over the world. Wheat production was increased from 585,691 thousand tons in 2000 to 713,183 thousand tons in 2013 which was ranked below rice and maize in case of production (FAO, 2015). In the developing world, need for wheat will be increased 60 % by 2050 (Rosegrant and Agcaoili, 2010). The International Food Policy Research Institute projections revealed that world demand for wheat will increase from 552 million tons in 1993 to 775 million tons by 2020 (Rosegrant et al.,1997). Wheat grain is the main staple food for about two third of the total population of the world. (Hanson et al., 1982).

It supplies more nutrients compared with other food crops. Wheat grain is rich in food value containing 12% protein, 1.72% fat, 69.60% carbohydrate and 27.20% minerals (BARI, 2006). It is the second most important cereal crop after rice in Bangladesh. So, it is imperative to increase the production of wheat to meet the food requirement of vast population of Bangladesh that will secure food security. During 2013-14 the cultivated area of wheat was 429607 ha having a total production of 1302998 metric tons with an average yield of 3.033 metric tons ha^-1whereas during 2012-13 the cultivated area of wheat was 416522 ha having a total production of 1254778 metric tons with an average yield of 3.013 tons ha^-1 (BBS, 2014).

Current demand of wheat in the country is 3.0-3.5 million tons. Increasing rate of consumption of wheat is 3% per year (BBS, 2013). Wheat production is about 1.0 milllion from 0.40 million hectares of land. Bangladesh has to import about 2.0-2.5-million-ton wheat every year. Wheat is grown all over Bangladesh but wheat grows more in Dhaka, Faridpur, Mymensingh, Rangpur, Dinajpur, Comilla districts. Wheat has the umpteen potentialities in yield among other crops grown in Bangladesh. However, yield per hectare of wheat in Bangladesh is lower than other wheat growing countries in the world due to various problems.

Increasing food production of the country in the next 20 years to much population growth is a big challenge in Bangladesh. It is more difficult because, land area devoted to agriculture will decline and better-quality land and water resources will be divided to the other sector of national economy. In order to grow more food from marginal and good quality lands, the quality of natural resources like seed, water, varieties and fuel must be improved and sustained. Variety plays an important role in producing high yield of wheat because different varieties responded differently for their genotypic characters, input requirement, growth process and the prevailing environment during growing season.

In Bangladesh the wheat growing season (November-March) is in the driest period of the year. Wheat yield was declined by 50% owing to soil moisture stress. Irrigation water should be applied in different critical stages of wheat for successful wheat production. Shoot dry weight, number of grains, grain yield, biological yield and harvest index decreased to a greater extent when water stress was imposed at the anthesis stage while water stress was imposed at booting stage caused a greater reduction in plant height and number of tillers (Gupta et al., 2001). Determination of accurate amount of water reduces irrigation cost as well as checks ground water waste. Water requirements vary depending on the stages of development. The pick requirement is at crown root initiation stage (CRI). In wheat, irrigation has been recommended at CRI, flowering and grain filling stages. However, the amount of irrigation water is shrinking day by day in Bangladesh which may be attributed to filling of pond river bottom. Moreover, global climate change scenarios are also responsible for their scarcity of irrigation water. So, it is essential to estimate water saving technique to have an economic estimate of irrigation water.

Information on the amount of irrigation water as well as the precise sowing time of wheat with change in climate to expedite wheat production within the farmer’s limited resources is inadequate in Bangladesh. The need of water requirement also varies with sowing times as the soil moisture depletes with the days after sowing in Bangladesh as there is scanty rainfall after sowing season of wheat in general in the month of November.

With above considerations, the present research work was conducted with the following objectives:

1. To evaluate yield performance of selected wheat genotypes(s) at variable irrigation management.
2. To identify the suitable genotype (s) of wheat giving higher yield under moisture stress condition.

2. Materials a nd Methods

2.1 Description of the experimental site

The experiment was conducted in the Research Field, Sher-e-Bangla Agricultural University (SAU), Dhaka-1207 during the period of November, 2016 to March, 2017 to observe the growth and yield performance of selected wheat genotypes at variable irrigation management. The experimental field is located at 23041´ N latitude and 90º 22´ E longitude at a height of 8.6 m above the sea level belonging to the Agro-ecological Zone “AEZ-28” of Madhupur Tract (BBS, 2013).

2.2 Soil characteristics

The soil of the research field is slightly acidic in reaction with low organic matter content. The selected plot was above flood level and sufficient sunshine was available having available irrigation and drainage system during the experimental period. Soil samples from 0-15 cm depths were collected from experimental field. The experimental plot was also high land, having pH 5.56.

2.3 Climate condition

The experimental field was situated under sub-tropical climate; usually the rainfall is heavy during Kharifseason, (April to September) and scanty in Rabi season (October to March). In Rabi season temperature is generally low and there is plenty of sunshine. The temperature tends to increase from February as the season proceeds towards kharif. Rainfall was almost nil during the period from November 2016 to March 2017 and scanty from February to September.

2.4 Planting material

The test crop was wheat (Triticumaestivum). Three wheat varieties BARI Gom-26, BARI Gom-28 and BARI Gom-30 were used as test crop and were collected from Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur.

2.5 Treatments

The experiment consisted of two factors and those were the wheat genotypes and irrigation. Three wheat genotypes and four irrigations were used under the present study. Factor A: three wheat varieties- V₁ = BARI Gom-26, V₂ = BARI Gom-28 and V₃ = BARI Gom-30. Factor B: four irrigations- I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling) and I₃= Three irrigation (Irrigate at CRI, booting and grain filling stages). The experiment was laid out in a split plot design with three replications having irrigation application in the main plots, verities in the sub plots. There were 12 treatments combinations. The total numbers of unit plots were 36. The size of unit plot was 2 m x 2 m = 4.00 m². The distances between sub-plot to sub-plot, main plot to main plot and replication to replication were, 0.75, 0.75 and 1.5 m, respectively.

2.6 Statistical analysis

The collected data on each plot were statistically analyzed to obtain the level of significance using the computer-based software MSTAT-C developed by Gomez and Gomez, 1984. Mean difference among the treatments were tested with the least significant difference (LSD) test at 5 % level of significance.

3. Results a nd Discussion

3.1 Plant height

Plant height varied significantly among the tested three varieties (Table 1). At, 75 DAS, BARI Gom 30 showed the tallest plant height (34.72 cm) and BARI Gom 26 recorded the shortest plant height (32.32 cm). At, 90 DAS, BARI Gom 30 recorded the highest plant height (76.13 cm) was observed from BARI Gom 26. However, BARI Gom 26 recorded the shortest plant height (75.01 cm) which was also statistically similar with BARI Gom 28. Islam and Jahiruddin (2008) also concluded that plant height varied significantly due to various wheat varieties. Plant height of wheat showed statistically significant variation due to amount of irrigation at 75, 90 DAS under the present trial (Table 2). At 75 DAS, the tallest plant (34.78 cm) was recorded from I₃ (Three irrigation) while the shortest plant (32.02 cm) was observed from I₀ (No Irrigation throughout the growing season) treatment. At 60 DAS, the tallest plant (77.51 cm) was found from I₃, which was statistically similar with I₂ (Two irrigation) and I₁ (One irrigation). The shortest plant (71.29 cm) was observed from I₀. Plant height was likely increased due to applying higher amount of irrigation compared to less amount of irrigation. Sultana (2013) stated that increasing water stress declined the plant height. Interaction effect of variety and different amount of irrigation showed significant differences on plant height of wheat at 75 and 90 DAS (Table 3). The highest plant height at 30 was 38.00 cm obtained from V₃I₃ treatment combination. The shortest plant height at 30 was 30.67 cm obtained from V₁I₀ treatment combination. At 60 DAS, plant height was 78.50 cm obtained from V₃I₃ and lowest was 69.83 cm obtained from V₁I₀ treatment combination, which was statistically similar with V₂I₀ and ₃I₀ treatment combination.

Table 1. Effect of variety on plant height of wheat at different days after sowing

Treatments	Plant height (cm)
		75 DAT	90 DAT
V1	32.32 a	75.1 a
V2	33.21 b	75.2 a
V3	34.72 c	76.13 b
LSD (0.05)	2.21	2.16
CV (%)	3.71	5.00

V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30

Table 2. Effect of irrigation on plant height of wheat at different days after sowing

Treatments	Plant height (cm)
		75 DAT	90 DAT
I0	32.02 a	71.29 a
I1	33.23 a	76.27 b
I2	33.63 b	76.83 b
I3	34.78 c	77.51 c
LSD (0.05)	2.21	2.16
CV (%)	3.71	5.00

I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages)

Table 3. Interaction effect of variety and irrigation on plant height of wheat

Treatment	Plant height (cm)
		75 DAS	90 DAS
V1I0	30.67 e	69.83 c
V1I1	33.50 bcd	76.67 ab
V1I2	34.00 bcd	77.00 ab
V1I3	34.67 bc	76.90 ab
V2I0	32.50 cde	71.83 c
V2I1	33.27 bcd	75.40 b
V2I2	31.83 de	76.43 ab
V2I3	31.67 de	77.13 ab
V3I0	32.90 bcde	72.20 c
V3I1	32.93 bcde	76.73 ab
V3I2	35.07 b	77.07 ab
V3I3	38.00 a	78.50 a
LSD (0.05)	2.11	2.26
CV (%)	3.73	5.00

In a column means having similar letter (s) are statistically similar and those having dissimilar letter (s) differ significantly by LSD at 0.05 level of probability.

V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30

I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages)

3.2 Number of effective tiller hill ^-1

Number of effective tillers hill^-1of wheat was not varied significantly due to varieties (Table 4). BARI Gom 30 produced the highest number of effective tillers hill^-1 (9.33) and the lowest number of effective tillers hill^-1(8.58) was observed in BARI Gom 26. Different levels of irrigation varied significantly in terms of number of effective tillers hill^-1 of wheat at harvest under the present trial (Table 5). The highest number of effective tillers hill^-1 9.89 was recorded from I₃ treatment, while the corresponding lowest number of effective tillers hill^-1 were 7.89 observed in I₀ treatment. Sultana (2013) stated that increasing water stress reduced the number of tillers per hill. Variety and irrigation showed significant differences on number of effective tillers hill^-1 of wheat due to interaction effect (Table 6). The highest number of effective tillers hill^-1 10.33 were observed from V₃I₃ treatment combination, while the corresponding lowest number of effective tillers hill^-1 as 7.33 were recorded from V₁I₀ treatment combination.

3.3 Number of non-effective tiller hill ^-1

Number of non-effective tillers hill^-1of wheat was not varied significantly due to varieties (Table 4). BARI Gom 26 produced the highest number of non-effective tillers hill^-1 (1.33) and the lowest number of non-effective tillers hill^-1(1.00) was observed in BARI Gom 30. Different levels of irrigation varied significantly in terms of number of non-effective tillers hill^-1 of wheat at harvest under the present trial (Table 5). The highest number of non-effective tillers hill^-1 (2.00) was recorded from I₀, while the corresponding lowest number of non-effective tillers hill^-1 (0.67) was observed in I₃. Variety and irrigation showed significant differences on number of non-effective tillers hill^-1 of wheat due to interaction effect (Table 6). The highest number of non-effective tillers hill^-1 (2.33) were observed from V₁I₀ treatment combination, while the corresponding lowest number of non-effective tillers hill^-1 (0.33) were recorded from V₃I₂ treatment combination.

Table 4. Effect of variety on yield and yield contributing characters of wheat

Treatment	Number of effective tiller per plant	Number of non-effective tiller per plant	Length of spike (cm)	Number of grain per spike
V1	8.58	1.33	8.08	36.92 b
V2	8.83	1.08	8.13	37.25 b
V3	9.33	1.00	8.46	37.75 a
LSD (0.05)	NS	NS	NS	0.50
CV (%)	9.81	5.22	8.66	5.73

V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30

Table 5. Effect of irrigation on yield and yield contributing characters of wheat

Treatment	Number of effective tiller per plant	Number of non-effective tiller per plant	Length of spike (cm)	Number of grain per spike
I0	7.89 b	2.00 a	7.17 c	34.56 c
I1	8.67 ab	1.11 b	8.11 b	36.33 b
I2	9.22 ab	0.89 bc	8.44 ab	39.00 a
I3	9.89 a	0.67 c	9.17 a	39.33 a
LSD (0.05)	1.68	0.40	0.85	0.90
CV (%)	9.81	5.22	8.66	5.73

I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages)

Table 6. Interaction effect of variety and irrigation on yield and yield contributing characters of wheat

Treatment	Number of effective tiller per plant	Number of non effective tiller per plant	Length of spike (cm)	Number of grain per spike
V1I0	7.33 d	2.33 a	6.50 c	34.00 e
V1I1	8.67 abcd	0.67 cd	8.33 b	36.00 cde
V1I2	8.67 abcd	1.33 abcd	8.83 b	38.00 abcd
V1I3	9.67 abc	1.00 bcd	8.67 b	39.00 abc
V2I0	8.33 bcd	2.00 ab	7.50 bc	35.00 de
V2I1	8.33 bcd	0.67 cd	8.00 b	37.00 bcde
V2I2	9.00 abcd	0.67 cd	8.50 b	40.00 ab
V2I3	9.67 abc	1.00 bcd	8.50 b	37.00 bcde
V3I0	8.00 cd	1.67 abc	7.50 bc	34.67 de
V3I1	9.00 abcd	1.00 bcd	8.00 b	36.00 cde
V3I2	10.00 ab	0.33 d	8.00 b	40.00 ab
V3I3	10.33 a	1.33 abcd	10.33 a	41.00 a
LSD (0.05)	1.48	1.03	1.21	3.43
CV(%)	9.81	5.22	8.66	5.73

In a column means having similar letter (s) are statistically similar and those having dissimilar letter (s) differ significantly by LSD at 0.05 level of probability. V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30

I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages)

3.4. Spike length (cm)

Insignificant variation was observed on spike length (cm) at applied three types of modern wheat variety as BARI Gom-26 (V₁), BARI Gom-28 (V₂), and BARI Gom-30 (V₃). From the experiment with that three types of varieties BARI Gom-30 (V₃) (8.46 cm) given the largest spike length and BARI Gom-26 (V₁) (8.08 cm) was given the lowest spike length (Table 4). Similar result was found using with different type varieties by Hefni et al. (2000). Different irrigation application has a statistically significant variation on spike length as irrigated condition (I₃) was given the maximum result (9.17 cm) and non-irrigated condition (I₀) given the lowest spike length (7.17 cm) (Table 5). Interaction effect of improved wheat variety and irrigation showed significant differences on spike length. Results showed that the highest spike length was obtained from V₃I₃ (10.33 cm). On the other hand, the lowest spike length was observed at V₁I₀ (6.50cm) treatment combination (Table 6).

3.5. Grain spike ^-1

Significant variation was observed on grain spike^-1 at these applied three types of modern wheat variety. The BARI Gom-30 (V₃) (37.75) given the maximum number of grain spike^-1 and BARI Gom-26 (V₁) (36.92) was given the lowest number of grain spike^-1, which was statistically similar with V₂ treatment (Table 4). Different wheat genotypes have significant effect on grain spike^-1 observed also by Rahman et al. (2009). Different irrigation application has a statistically significant variation on grain spike^-1 as the irrigation condition (I₃) was given the maximum result (39.33), which was statistically similar with I₂ and non-irrigated condition (I₀) given the lowest grain spike^-1 (34.56) (Table 5). Sarkar et al. (2010) also observed that irrigation have a significant effect on grain spike^-1. Interaction effect of improved wheat variety and irrigation showed significant differences on grain spike^-1. Results showed that the highest grain spike^-1 was obtained from V₃I₃ (41.0). On the other hand, the lowest grain spike^-1 was observed at V₁I_o (34.00) which were also statistically similar with V₃Io (34.67) (Table 6).

3.6. Thousand Seed weight

There was significant variation was observed on thousand seed weight due to different types of modern wheat variety. The wheat variety of BARI Gom-30 (V₃) (50.40 g) given the maximum thousand seed weight and statistically different from BARI Gom-28 (V₂) (46.74 g). BARI Gom-26 (V₁) (46.22 g) was given the lowest thousand seed weight (Table 7). Rahman et al. (2009), Islam et al. (2015) also conducted experiment with different variety and observed have effect of varieties on yield. Different irrigation application has a statistically significant variation on thousand seed weight. The I₃ was given the maximum thousand seed weight (48.91) and non-irrigated condition (I₀) given the lowest yield (46.13 g) (Table 8). Sarkar et al. (2010), Baser et al. (2004) reported that grain yield under non-irrigated conditions was reduced by approximately 40%. Bazza et al. (1999) reported that one water application during the tillering stage allowed the yield to be lower only than that of the treatment with three irrigations but Meena et al. (1998) reported that wheat grain yield was the highest with 2 irrigations (2.57 ton/ha in 1993 and 2.64 ton/ha) at flowering and/or crown root initiation stages. Wheat is sown in November to ensure optimal crop growth and avoid high temperature and after that if wheat is sown in the field it faces high range of temperature for its growth and development as well as yield potential. Islam et al. (2015) reported that late planted wheat plants faced a period of high temperature stress during reproductive stages causing reduced kernel number spike^-1 as well as the reduction of grain yield. Interaction effect of improved wheat variety and irrigation showed significant differences on thousand seed weight (Table 9). Results showed that the highest thousand seed weight (52.33 g) was obtained from V₃I₃ which was statistically similar with V₃I₂ (52.06 g). On the other hand, the lowest yield (45.36 g) was observed at V₁I₁.

Table 7. Effect of variety on yield and yield of wheat

Treatment	Thousand seed weight (g)	Yield (t/ha)	Straw yield (t/ha)	Biological yield (t/ha)
V1	46.22 c	3.21 b	1.87 b	5.08 b
V2	46.74 b	3.43 a	1.90 b	5.33 ab
V3	50.40 a	3.44 a	1.95 a	5.39 a
LSD (0.05)	0.5091	0.1571	0.0497	0.2721
CV (%)	6.27	6.34	7.39	11.00

V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30

Table 8. Effect of irrigation on yield and yield of wheat

Treatment	Thousand seed weight (g)	Yield (t/ha)	Straw yield (t/ha)	Biological yield (t/ha)
I0	46.13 d	2.97 b	1.80 c	4.77 d
I1	47.49 c	3.16 b	1.88 bc	5.03 c
I2	48.60 b	3.56 a	1.94 ab	5.50 b
I3	48.91 a	3.74 a	2.01 a	5.76 a
LSD (0.05)	0.27	0.28	0.12	0.23
CV (%)	6.27	6.34	7.39	11.00

I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages)

Table 9. Interaction effect of variety and irrigation on yield and yield of

wheat

Treatment	Thousand seed weight (g)	Grain yield (t/ha)	Straw yield (t/ha)	Biological yield (t/ha)
V1I0	45.65 fg	2.93 d	1.78 e	4.72 f
V1I1	45.36 g	3.21cd	1.89 cd	5.09 def
V1I2	46.70 cde	3.33 bcd	1.83de	5.16 cde
V1I3	47.15 cd	3.38 bc	1.96 bc	5.34 cd
V2I0	46.10 ef	2.99 cd	1.79 e	4.77 ef
V2I1	46.55 de	3.26 bcd	1.91 cd	5.17 cde
V2I2	47.04 cd	3.60 ab	1.91 cd	5.51 bc
V2I3	47.25 c	3.86a	2.00 ab	5.86 ab
V3I0	46.64 cde	3.00 cd	1.83 de	4.84 ef
V3I1	50.54 b	3.00 cd	1.83de	4.83 ef
V3I2	52.06 a	3.75 a	2.07 a	5.82 ab
V3I3	52.33 a	3.99 a	2.08 a	6.07 a
Lsd (0.05)	0.56	0.36	0.08	0.36
CV(%)	6.27	6.34	7.39	11.00

In a column means having similar letter (s) are statistically similar and those having dissimilar letter (s) differ significantly by LSD at 0.05 level of probability.

V₁ = BARI Gom 26, V₂ = BARI Gom 28, V₃ = BARI Gom 30

I₀ = No Irrigation throughout the growing season, I₁ = One irrigation (Irrigate at CRI stage), I₂= Two irrigation (Irrigate at CRI and grain filling), I₃= Three irrigation (irrigate at CRI, booting and grain filling stages)

3.7. Grain yield (t ha ^-1 )

Different wheat varieties showed significant difference for grain weight hectare^-1 (Table 7). The highest grain yield hectare^-1 (3.44 ton) was found from wheat variety BARI Gom-30 (V₃), which was statistically similar with V₂, whereas the lowest (3.21 ton) was observed from wheat variety BARI gom 26. Rahman et al. (2009), Islam et al. (2015) also conducted experiment with different variety and observed have effect of varieties on yield. Significant difference was observed for yield for different irrigation application. The three irrigation (I₃) was given the maximum yield (3.74 t ha^-1), which was statistically similar with I₂ treatment and non-irrigated condition (I₀) given the lowest yield (2.97 t ha^-1) (Table 8). Sarkar et al. (2010), Baser et al. (2004) reported that grain yield under non-irrigated conditions was reduced by approximately 40%. Bazza et al. (1999) reported that one water application during the tillering stage allowed the yield to be lower only than that of the treatment with three irrigations but Meena et al. (1998) reported that wheat grain yield was the highest with 2 irrigations (2.57 ton/ha in 1993 and 2.64 ton/ha) at flowering and/or crown root initiation stages. Wheat is sown in November to ensure optimal crop growth and avoid high temperature and after that if wheat is sown in the field it faces high range of temperature for its growth and development as well as yield potential. Islam et al. (2015) reported that late planted wheat plants faced a period of high temperature stress during reproductive stages causing reduced kernel number spike^-1 as well as the reduction of grain yield. Interaction effect of improved wheat variety and irrigation showed significant differences on yield (t ha^-1). Results showed that the highest yield (3.99 t ha^-1) was obtained from V₃I₃, which was statistically similar with V₂I₃ and V₃I₂. On the other hand, the lowest yield (2.93 t ha^-1) was observed at V₁I₀ (Table 7).

3.8. Straw yield (t ha ^-1 )

Applied three types of wheat variety have a statistically significant variation on straw yield (t ha^-1). The maximum straw yield (1.95 t ha^-1) was obtained from BARI Gom-30 and BARI Gom-26 (V₁) was given the lowest straw yield (1.87 t ha^-1), which was statistically similar with V₂ treatment. Different irrigation application has a statistically significant variation on straw yield (t ha^-1) of wheat. The I₃ treatment for straw yield (2.01 t ha^-1) was given the maximum result and non-irrigated condition (I₀) given the lowest (1.80 t ha^-1). Similar results were found by Ali and Amin (2004) through his experiment. Interaction effect of improved wheat variety and irrigation showed significant differences on straw yield (t ha^-1). The highest straw yield (2.08 t ha^-1) was obtained from V₃I₃ which was statistically similar with V₃I₂ (2.07 t ha^-1) treatment combination. On the other hand, the lowest straw yield (1.78 t ha^-1) was observed at V₁Io, which was statistically similar with V₂I₀ (2.07 t ha^-1) treatment combination.

3.9. Biological yield

Significant variation was attained for biological yield for different wheat varieties. The variety BARI Gom-30 given the maximum biological yield (5.39 t ha^-1) and BARI Gom-26 (V₁) was given the lowest biological yield (5.078 t ha^-1). Different irrigation application has a statistically significant variation biological yield (t ha^-1) of wheat. The I₃ treatment for biological yield (5.76 t ha^-1) was given the maximum result and non-irrigated condition (I₀) given the lowest (4.77 t ha^-1). Similar results were found by Ali and Amin (2004) through his experiment. At the time of biological yield (t ha^-1) consideration with variety and irrigation statistically significance variation was observed as maximum biological yield (t ha^-1) at V₃I₃ (6.07 t ha^-1). On the other hand, the lowest result was given at V₁Io (4.72 tha^-1).

References

1. Ali, M. N.; Amin, M. S. (2004). Effect of single irrigation and sowing date on growth and yield of wheat. M. S. thesis, SAU, Dhaka, Bangladesh.
2. BARI. (Bangladesh Agricultural Research Institute). (2006). Handbook of Agricultural Technology. Joydebpur, Gazipur.p.9.
3. Baser, I.; Sehirali, S.; Orta, H.; Erdem, T.; Erdem, Y. and Yorganclar, O. (2004). Effect of different water stresses on the yield and yield components of winter wheat. Cereal Res. Comn.; 32(2): 217-223.
4. Bazza, S. S.; Awasthi, M. K. and Nema, R. K. (1999). Studies on Water Productivity and Yields Responses of Wheat Based on Drip Irrigation Systems in Clay Loam SoilIndian J. Sci. Tech. 8(7):650–654.
5. BBS. (2013). Bangladesh Bureau of Statistics, Ministry of Planning, Government of the Peoples Republic of Bangladesh, Dhaka.
6. BBS. (2014). Bangladesh Bureau of Statistics, Ministry of Planning, Government of the Peoples Republic of Bangladesh, Dhaka.
7. Gomez. K. A.; Gomez, A. A. 1984. Statistical Procedures for Agricultural Research. 2nd edition. John Willy and Sons, New York. pp. 28-192.
8. Gupta, P. K.; Gautam, R. C.; Ramesh, C. R. (2001). Effect of water stress on different stages of wheat cultivation. Plant Nutri. andFert. Sci., 7(2): 33-37.
9. Hanson, M.; Farooq, M.; Shabir, G.; Khan, M. B.; Zia, A. B. and Lee, D. G. (1982). Effect of date sowing and rate of fertilizers on the yield of wheat under irrigated condition. Intl. J. Agril. & Biol. 14(4), 25-31.
10. Hefni, S.; Sajjad, A.; Hussain M. I. and Saleem, M. (2000). Growth and yield response of three wheat varieties to different seeding densities. Int. J. Agric. Biol. 3 (2): 228-229.
11. Islam, S.; Islam, S.; Uddin, M. J.; Mehraj, H. and Jamal Uddin, A. F. M. (2015). Growth and yield response of wheat to irrigation at different growing stages. Int. J. Agron. Agril. Res. 6 (1): 70-76.
12. Meena, B. N.; Tunio, S. D.; Shah, S. Q. A.; Sial, M. A.; Abro, S. A. (1998). Studies on grain and grain yield associated traits of bread wheat (Triticum aestivum L.) Varieties under water stress conditions. Pakistan J. Agric. Agril. Engin. Vet. Sci.; 24(2): 5-9.
13. Rahman, M. M.; Hossain, A.; Hakim, M. A.; Kabir, M. R.; Shah, M. M. R. (2009). Performance of wheat genotypes under optimum and late sowing condition. Int. J. Sustain Crop Prod. 4(6): 34-39.
14. Rosegrant, M. W.; Agcaoili, M. (2010). Global food demand, supply, and price prospects to 2010. Washington, DC: Int. Food Policy Res. Inst.
15. Rosegrant, M. W.; Sombilla, M. A.; Gerpacio R. V. and Ringler, C. (1997). Global food markets and US exports in the twenty-first century. Paper prepared for the Illinois World Food and Sustainable Agriculture Program Conference ‘Meeting the Demand for Food in the 21^st Century: Challenges and Opportunities for Illinois Agriculture’, May 27.
16. Sarker, S.; Singh, S. K.; Singh, S. R.; Singh, A. P. (2010). Influence of initial profile water status and nitrogen doses on yield and evapotranspiration rate of dryland barley. J. Indian Soc. Soil Sci. 47(1): 22-28.
17. Sultana, F. (2013). Effect of irrigation on yield and water use of wheat. M.S. Thesis, Dept. of Irrigation and Water Management. Bangladesh Agril. Univ.; Mymensingh.

4. Summary a nd Conclusion

It may be concluded within the scope and limitation of the present study that the optimum growth and higher yield of wheat cv. BARI Gom-30 could be obtained by applying three irrigations at irrigate at CRI, booting and grain filling stages. However, further studies are necessary to arrive at a definite conclusion.