Heat Accumulation, Nutrient Content and Yield of Wheat ( Tritichum Aestivum L .) Varieties in Bangladesh

tolerant varieties get and physiological (GDD) in longer duration of vegetation as well ABSTRACT An experiment was conducted with twelve BARI wheat verities at Regional Agricultural Research Station, Ishwardi, Pabna during two consecutive years of 2016-2017 and 2017-2018 in Bangladesh. Selected wheat varieties were BARI Gom-21, BARI Gom-23, BARI Gom-24, BARI Gom-25, BARI Gom-26, BARI Gom-27, BARI Gom-28, BARI Gom-29, BARI Gom-30, BARI Gom-31, BARI Gom-32 and BARI Gom-33 as treatment. Phenological duration and Growing Degree Day (GDD) showed variation among the wheat varieties. BARI Gom-26, BARI Gom-27, BARI Gom-28, BARI Gom-29, BARI Gom-30, BARI Gom-31, BARI Gom-32 and BARI Gom-33 were found more suitable as heat tolerant varieties in respect of higher heat use efficiency (2.71-3.09 kg/ha/GDD) producing higher grain yield (4.98-5.47 t/ha) associated with better yield components. Grain yield was positively correlated with Heat Use Efficiency (HUE) (r=0.86 at p<0.01) and effect of HUE on grain yield was about 74% (Y=1.6248+1.2383x, R² = 0.74). BARI Gom-21, BARI Gom-23, BARI Gom-25, BARI Gom-26 BARI Gom-30 and BARI Gom-33 were identified as protein (13.13-14.75%) rich varieties. Content of N (1.85-2.36%), P (0.03-0.16%), K (0.32-0.54%), S (0.22-0.37%), Ca (0.51-0.67%), Na (0.09-0.15%) and B (5.12-7.39 ppm) noticed variation among the varieties. BARI Gom-25 and BARI Gom-26 were found as Zn (35-38 ppm) and Fe (123-126 ppm) rich but BARI Gom-31 was found as Zn (35-38 ppm) rich wheat varieties. to observe the accumulation and nutrient content of varieties in


Introduction
Wheat is a widely adapted cereal food crop grown in temperate, warm and humid, dry and cool environments Hakim, et al. [1]. The crop is cultivated worldwide Tahir, et al. [2] and as a staple food over 60 counties Nipa, et al. [3] with an increasing demand day by day. In Bangladesh condition, wheat is a second cereal food grain after rice. Wheat cultivation area covers about 330348 hectares of land with an annual production of 1016811 tones in Bangladesh [4]. Bangladesh has experienced in climate change effect as the global warming. Under climate change situation winter is becoming shorter and temperature is rising Mian, et al. [5]. Generally wheat grows after T.aman rice following T.aman-Wheat cropping pattern in Bangladesh Mian, et al. [6]. Consequently, high temperature stress at the terminal of growing season usually constrains crop yield potential as the stress coincides with the grain filling period of wheat Tahir, et al. [2]. Temperature is the single most important climatic factor affecting the growth and development of crop plant. It also influences different physiological process in the plant system. High temperature affects phenology, growth and yield of crop Mian, et al. [5]. Due to variation of air temperature, heat accumulation (Growing Degree Day: GDD) in crop plant and phenological development is always changing Mian, et al. [7]. More accumulation of heat unit (GDD) is an important phenomenon of heat tolerant varieties of wheat Mian, et al. [8]. Heat tolerant varieties get long phenological duration for heading (flowering) and physiological maturity. Consequently, more heat unit (GDD) accumulation occurs in longer duration of vegetation phase as well starts after accumulation of certain amount of heat unit in a specific variety in an ideal environment without any stress. Heat tolerant varieties are more preferable to wheat grower in Bangladesh due to delay harvesting of T.aman rice. Boro rice is a major crop and it is competitive to wheat in winter season in Bangladesh. Wheat cultivation requires less cost as compared to boro rice.
The crop also requires less water as compared to boro rice.
Thus, wheat cultivation can save underground water use as compared to boro rice cultivation in Bangladesh condition. Being a major source of starch and energy, wheat also provides substantial amounts of protein, minerals, fat, calcium, iron, carotene, vitamin B-1, vitamin B-2 and other phytochemicals which are essential or beneficial for human and animal health [9]. Wheat grain protein concentration is an important determinant of wheat quality for human nutrition but very often overlooked to improve it Muelber, et al. [10]. Nutrient content in wheat varied significantly due to change of environment as the change of sowing dates Pan, et al. [1,11]. Protein content increased with the increase of maturity period of wheat Hossain, et al. [12]. Protein percent (%) in wheat flour increased with the increase of temperature Muelber, et al. [10].
There exists a relationship between nutrient content in wheat with the change of environment Pan, et al. [11]. Grain yield is positively correlated with GDD to heading duration and maturity duration Al-Karaki [8,13]. Bangladesh Agricultural Research Institute (BARI) has developed a good number of modern wheat varieties.
Research on nutritional status of wheat was done for some earlier developed varieties Hakim, et al. [1,3]. However, there is a little research work regarding heat accumulation and nutrient content of wheat varieties in Bangladesh condition. Therefore, the study was undertaken to observe the heat accumulation and nutrient content of BARI wheat varieties in Bangladesh condition.

Materials and Method
The experiment was conducted at Regional Agricultural

Where
Base Temperature for wheat is 5 0 C.
Heat Use Efficiency (HUE) and Phenothermal index (PTI) were calculated after Akhter et al. [19] as follows.
Heat use efficiency ( There was no significant difference from year to year about the studied parameters of wheat. Hence, the paper has been written with the pooled values of the parameters.

Phenological Duration and Heat Accumulation
Heading duration varied significantly among the varieties of wheat (Table 1). Longer heading duration (67 day) was noticed in BARI Gom-33 followed by BARI Gom-21 (66 day), BARI Gom-23 (65 day), BARI Gom-27 (65 day) and BARI Gom-31 (65 day) while the shorter duration was found in BARI Gom-25 (61 day) and BARI Gom-30 (62 day) ( Longer physiological maturity duration (day) enhanced to more heat accumulation (GDD) in wheat. Similar results also have been described by other investigators Kumar [17,18]. The GDD might be varied or reduced in a variety due to some stress condition when the crop got forced maturity receiving shorter physiological maturity period. The results are in agreement with the observation of Kumar [17], and Mian, et al. [8]. Heat Use Efficiency (HUE) showed variation among the varieties giving the highest value (3.03- 3.09 kg/ha/GDD) in BARI Gom-28 and BARI Gom-30 but the lowest value (2.56-2.69 kg/ha/GDD) in BARI Gom-21 BARI Gom-23 BARI Gom-24 and BARI Gom-25 (Table 1)

Nutrient Content
Concentration of N, P, K, S and Zn was found variation among the varieties ( Concentration of Zn was found higher (38 ppm) in BARI Gom-25, BARI Gom-26 followed by BARI Gom-31 (35 ppm) and the lowest in BARI Gom-21 (31 ppm) ( Table 2). These nutrient concentration was also found variation in wheat varieties by Nipa et al. [3].
Concentration of Ca, Fe, Na and B was found variation among the varieties ( Table 3). Concentration of Ca was found the highest (0.67%) in BARI Gom-31 and BARI Gom-33 followed by BARI Gom-29 (0.65%) while giving the lowest value in BARI Gom-24 (0.51%) (