Effect of Hill Temperature on Wheat Variety Development and Yield in the District of Khagrachari

. ABSTRACT The experiment which likened the execution of high-placed outcome briefly cold duration and heat-tolerant varieties under increasing temperature was carried out in two successive crop seasons (2017-18 and 2018-19) at a farmer's field in Maniksari Upzila within Khagrachari Hill District during the Rabi season (November – March). Early mature wheat types made available by BARI were sown at the ideal time and were heat, saline tolerant as a coping strategy for extreme heat stress. There were six short time wheat cultivars developed recently in heat and stress (BARI Gom 25, BARI Gom 28, BARI Gom 30, BARI Gom 32, BARI Gom 33 and Advance Line BAW 1147). BARI Gom 33 (3.86 t/ha and 3.80 t/ha) and BARI Gom 30 (3.78 t/ha and 3.56 t/ha) produced the highest crop yields over the course of a few years. BARI Gom 32 (3.00 t/ha and 3.40 t/ha), Advance line 1147 (2.96 t/ha and 3.04 t/ha) and BARI Gom 28 (2.59 t/ha and 3.10 t/ha) were found the highest yields. BARI Gom 25 (2.74 t/ha and 2.89 t/ha) had the lowest yield. The quantity of biomass yield and wheat crop output differed significantly, but the other characteristics had little bearing. BARI Gom 25 was the earliest maturing variety, and BARI Gom 33 generated the highest crop output compared to other varieties. The highest benefit cost ratio (BCR) was 1.48 displayed by BARI Gom 33 and the lowest by BARI Gom 25 which was 1.08. According to the experiment's findings, BARI Gom 33 was among the six kinds in the Khagrachari Hills' early high producing and most adaptable variety. BARI Gom 30 also may be cultivated in the Khagrachari hills District.

wheat lines that can with stand biotic and abiotic stress (Mondal et al., 2016). A propos to secure food security, utter temperature oppression is necessary. For every degree Celsius increase, the output of wheat decreases by 4.1 to 6.4 percent (Liu et al., 2016). According to the discussion in high temperatures affect some yield metrics such as incipient weight and grain amount and weight (Akter et al., 2017). Particularly between spike initiation and anthesis, a large heat has an impact on grain number (Farook et al., 2011). High temperatures after anthesis diminish grain mass, especially if the treatment is started early (Gibson et al., 1994;Castro et al., 2007). Heat stress shortens the time grains fill up, as described in (Altenbach et al., 2012). When grains are filled at temperatures above 30°C, starch implication enzymes are less able to move through the grains, further lowering the amount of starch present (Hurkman et al., 2003;Corbellini et al., 1998). At present our country need about 65 lac MT wheat for mitigations of demand but our domestic output is respecting 12 lac MT that why we have to span valuable foreign currencies. Due consideration must be given to raising domestic wheat production by increasing wheat cultivation in non-traditional regions of the nation where cropping intensity is low and there are opportunities for wheat development. One tenth of the country or the Hill Tract regions are made up of 75% upland (hills), 20% undulating bumpy ground and 5% valley plain land (Ataur et al., 2015). Due to a lack of irrigation water needed for boro rice farming a vast bumpy undulating area and the valleys are left fallow in the winter. Wheat can be adult in the majority of areas with the narrow water capital that are there because its water consumption is less than one-fourth that of rice. Since the winter pattern and duration at the hill are different, the wheat's sowing date may be changed in an effort to maximize environmental benefits. In order to encourage the development of the promising cultivars in hill regions, disparities in varietal adoption may also exist. Following some articles (Rahman et al., 2013;Tang et al., 2003;Rahman et al., 2005) air temperatures, management practices (Rahman et al., 2002;Timsina and Cornor, 2001), and soil type, wheat variety yield performance varied. In response to changes in environmental conditions and elevation in the hill region, there may be varietal differences. It is possible to classify as adaptable in hilly areas the wheat types that yield more at the greater elevation of Khagrachuri. With the ultimate goal of expanding wheat in Bangladesh's non-traditional hill valleys, the current experiment preparation look at how different varieties responded to higher elevation and condition best seeding technique for that area.

MATERIALS AND METHODS: Experimental Soil Types
The experimental field's soils were severely acidic (pH 5 -5.2), with greater concentrations of Fe, Al, and Mn in the top 15 cm of soil and deficiencies in several vital plant nutrients such nitrogen (Total N = 0.07%-0.09%), phosphorus (Olsen P = 5.6 -6.4 ppm), and potassium (K = 0.18 -0.22 meq/100g). Sulfur and zinc levels in the soil were high, but the crucial boron content was deficient. Table 2 shows the physical and chemical data of the ground prior to conducting the experiment. Data gathered from locally agricultural offices in Khagrachari hill districts.

Weather condition of khagraghari durning 2018 -19
Experimental procedure For testing the hill environment in the Khagrachari district, we used medium-high valley terrain. Wheat accessions with short maturing temperatures were tasted in one habitat in Khagrachari. Information about plots, sowing dates, harvest dates and localities is taken into account. Cow dung (5 tons/ha) and 230-150-100-110-20-10 Kg/ha of NPKSZB were used to fertilize the crop accordingly. During the land preparation process, cow dung was applied. At the final cultivation of the ground preparation, two-thirds of N and the remainder of other chemical fertilizer were applied. At 17 to 21 days after sowing or at the CRI (crown root initiations) stage after irrigation, one third of N was applied as top dressing. During the CRI, booting and grain-filling stages, the crop were irrigated three times to bring the soil moisture level nearly to field capacity. At 35 DAS (date after sowing), weeds were once physically eradicated by hand weeding. Crops were properly harvested when they reached maturity, sun-adhesive and cleaned on a sub-plot basis. The kernel output was then converted to t/ha -1 at a moisture level of 12 percent after the grains had been dried in the air. Ten plants from every plot were collected prior to harvest in order to manipulation. Following a conventional procedure, the initial plant populations were further numbered at 20 DAS. Collaborators sub-mitted information on the crop's plant population (PP), height (PH), heading days (HD), spike/m, grain/spike, spikelet/spike, days to maturity (MD), kernel output (t/ha) and biomass yields (BY). HD was considered as the count of days from the date of sowing/first irrigation until half of the spikes from the flag leaf had emerged. 50% of the spikes' peduncles had MD, which is a sign of senescence. Plots were maturely harvested on March 7th to determine GY. The average grade was checked using the least significant difference (LSD) at a threshold of 5% after statistical analysis of the entire datum. Utilizing statistic-10 software, all parameters were examined for evaluation. LSD was predicted to incorporate the variety's average grain yield.

Experimental Design
In order to conduct their experiment by the Rabi seasons of 2017 -18 and 2018 -19, researchers used an RCBD (randomized complete block design) with 3 duplications and six treatments. The main field maintains a 20 cm line-to-line and 1 inch plant-to-plant spacing. 5 ×4 meter main plot is used. All genotype lines provided stable grain yields under normal, gradual planting conditions with irrigation. Stress caused by exalted heats. In this experiment, five recently released wheat cultivars and one advance line with quick ripening times and tolerance to temperature changes were used.   Because of this, BARI Gom 28 has the lowest kernel output in the 2017 -18 experiment. The number of spikes per square meter is a crucial element in influencing grain production. Spike/m 2 , the number of kernels is determined by the spike period which is determined by a person's genetic make-up. Environmental factors present at the time of the growth spike in grain production. The terminal kernel output is directly impacted by the wheat yield. Genetic differences across cultivars and varietals were most likely the cause of variations in the amount of spikes/m 2 (Islam, 1995). O'Toole and Stockle, (1991) state that when vegetative development and tillering advance towards the end of the GSI (Emergence to double in ridges) stage, susceptibility to heat rises. High temperature sensitivity shows up throughout this phase as a waning in the GS1 period along with a waning in leaf bound and growth (Shpiler and Blum, 1986). The overall amount of leaves and spike-bearing tillers is on the decline at this time of high temperatures (Midmore et al., 1984). How many tillers would be stable under a heat stress condition in the posterior would entirely depend on their genetic makeup. The majority of genotypes do not consistently perform well in all circumstances; genetic effects are not entirely independent of environmental factors. The relative ranking of genotypes for yield when a genotype interacts with its environment typically changes when genotypes are analyzed over many atmosphere and years (Al-Otayk, 2010).

Spikelets/spike
One important component in determining grain output is the grain's total spikelet/spike content. The reach of the spike, its genetic composition, as well as environmental factors present at the moment of development, all influence the amount of spike-lets/spikes. Depending on the developing conditions, the amount of spikelets or spikes affects how much grain the wheat grower will ultimately produce. According to data in These two genotypes may benefit from longer heat waves and more favorable temperatures for accrual and improvement than other genotypes. These types' ability to develop may be slightly hampered by hot temperatures. Variations in spikelet/spike number within cultivars and varietals were most likely caused by genetic variations (Islam, 1995). Temperatures were high from emergence to the GSI (double ridges stage), which had an impact on the composition of florets and led to a smaller grain spike in crops that were sown recently.
As vegetative development and tillering get closer to the last of the GSI stage, vulnerability to extreme heat is said to rise (O'Toole and Stockle, 1991). High temperature sensitivity is seen during this phase as a shortening of leaf area and growth as well as a reduction in the periods of GS1 (Shpiler and Blum, 1986). According to (Owen, 1971) and (Saini and Aspinal, 1982) temperatures above 30°C during floret formation cause 100% sterility, which results in fewer grains spike.
High wheat production might be forced by spikelet growth.

Grains/spike
The amount of kernels is a crucial component in spikes production. The numbers of grain depend on the shape of the spike, its genetic makeup, and any environmental factors present throughout the growth stage. Treatment T 5 BARI Gom 33 produced a greater quantity of grains spike-1, followed by Treatment T 3 BARI Gom 30 in two years ( Table 3). Treatment BARI Gom 28, which was comparable to treatment BARI Gom 25 treated plot, produced the fewest grains spike-1. The third and fourth higher numbers of grains spikes-1 were discovered in BARI Gom 32 and BAW 1147 treated plots, which may be related to those plots' comparatively longer spikes and greater numbers of spikelets/spike-1. The attendance of more nutrients as an outcome of nutritional variation may explain why there is noticeably more grains spike-1 in various treatments than in BARI Gom 33. Differences in grain size and spikes within cultivars and varietals were most likely caused by genetic variations (Islam, 2004)

1000-grain weight
In the current study, we discovered that treatment T 5 BARI Gom 33 produced the greatest 1000 kernel weight (43g) in the years 2017 -18 and (48g) in 2018 -19 respectively. The treatment's lowest 1000 kernel gravity was place to be Gom 28 (24g) in 2017 -18 and BARI Gom 25 (35g) in 2018-19 (Table 3). It might initially work in BARI Gom 33's favor, but against BARI Gom 28. However, other kinds consumed less heat than BARI Gom 33, especially during the kernel filling stage. The head was incredibly high the last few times at the kernel filling stage, which finally reduced yield and shortened every improvement phage. BARI Gom 30 (40g, 41g) in the last two years had the second-highest yield per 1000 kernels pursued by the BARI Gom 32 (36g) in 2017-18 and (39g) in 2018-19 years. 4 th and 5 th 1000 kernels was (30g), (26g) in 2017-18 and (38g), (37g) in 2018-19 years. According to Sofied et al. (1977), elevated grain weight was produced when a favorable temperature was linked with a full corn filling length. Lower 1000 kernel weight was documented in hilly areas during BARI Gom 28 (24g) and (37g) two years due to elevated temperatures throughout the outgrowth stage, parti-cularly after grain filling. This assertion is confirmed by the findings of Spink et al. (2000) and Shahzad et al. (2002) who also demonstrated losses in 1000 kernel weight with high temperature. Similar results have already been noted (Qamar et al., 2004;Subhan et al, 2004).

Plants maturity
In wheat accession, high temperatures reduced physiological swelling and output contribution. Maximum period is required for physiological maturity to reach adulthood. When the typical leaf and spike turn yellow, that is when something is physiologically mature (Hanft and Wych, 1982). According to the study, treatment T 5 BARI Gom 33 had the foremost physiological ripeness of the cultivars, reaching that stage after 89 days in 2017 -18 and 90 days in 2018 -19 (  Table 3) the duration of crop maturation is shortened by stress. Asana and Williams, (1965) found that mindless of accession for every 1 0 C increase in heats during the grain-filling phase the daytime of grain-filling decreased by around 3-days. Owen, (1971) and (Saini & Aspinal, 1982) claim that temperatures exceeding 30°C during floret production result in 70% sterility, which losses the amount of kernel spike. The spikelet growth may be due to the high wheat yield. The days to physiological of wheat accession also indicated a wide periods of results because of the intrinsic variations between the cultivars (Shahzad et al., 2007). According to Fischer, (1990), high temperatures reduce cultivars' life cycles from implantation to harvest and speed up their development.

Grain yield
Guilioni et al. (2003) set up that throughout the anthesis and grain-filling stages of many temperate cereal crops, heat stress alone or in conjunction with drought is a frequent constraint. For instance, the impacts of temperature stress on spring wheat kernels included a reduction in filling time and a slowing of growth, which led to losses of up to 7% in weight and density. The five types in our investigation were all strongly influenced by temperature, which judgmental in a notable loss in grain yield. On another way, genotypes varied in the rate of decline. According to Hasan (2002), every 1°C rise in the mean air heat from anthesis to ripeness compared to the typical growth conditions affects grain production by 2.6 to 5.8% in heattolerant cultivars and 7.2% in heat-sensitive cultivars.
The maximum kernel yield is produced by our hilly experiment with the cultivars BARI Gom 33 ( Table 3). According to Kumer et al. (1994), the termination of a hostile environment (high heat) during the vegetative cycle led to crops growing thinly and producing fewer tillers, which decreased straw yield. BARI Gom 33 produces the maximum biomass due to his resistance to heat. According to Donaldson et al. (2001) heat-tolerant optimal planting led to a better straw outcome because of the enhanced amount of tillers. These results support those of Matuz and Aziz, (1991).

Economic Analysis
It was done a simple economic analysis. They were mentioned to as fixed expenses since the prices for labor, irrigation, fertilizer, seed, and land preparation were same throughout all applications. The expenses of urea, triple super phosphate, murate of potash, gypsum, born, and zinc sulfate were all regarded as variable costs. The farm gate prices of the output were profit from farmers and local markets for the purposes of calculating gross return, net return, and benefit cost ratio (BCR). The remainder received the same treatment from each management. Total cost was counted as the product of fixed and variable costs (Total cost = Fixed cost + Variable cost). The gross return was calculated using the major product's farm gate selling price. By dividing the gross return, the total price and the gross margin, the BCR was computed. 52,000 taka/ha is the entire cost of production, according to the economic study (all treatment are same). The treatments with the maximum gross returns are T 5 =76,600 taka and T 3 =64400 taka, respectively ( Table 4). Third, fourth, and fifth brave comebacks following therapy T 3 , T 6 , and T 2 .The smallest bold recovery following treatment T 1 is 56,200 Taka. Gross return x total production cost is the BCR (benefit cost ratio) calculation. (Treatment = T 5 ) has a BCR of 1.48. T 3 therapy comes after (1.24). Therapy = T 1 has the lowest BCR (1.08). We may conclude that BARI Gom 33 is superior to other options in the Khagrachari area because of this. Local market wheat price 20/kg (taka), T 1 =BARI Gom 25, T 2 = BARI Gom 28, T 3 = BARI Gom 30, T 4 = BARI Gom 32, T 5 = BARI Gom 33, T 6 = BAW 1147.

CONCLUSION:
The conclusion is that the environment in hills has an important dominance on crop yield and its components. For the analyzed features of yield, the results showed that the BARI Gom 33 and BARI Gom 30 varieties significantly outperformed followed by the BARI Gom 32, BAW 1147, BARI Gom 28 and BARI Gom 25 accordingly. Wheat needs heat resistant genes to obtain higher yield and maturity. BARI Gom 33 and BARI Gom 30 are the best option for Khagrachari to get higher production.

ACKNOWLEDGEMENT:
The authors are grateful to the authority of the Regional Station (RS), BWMRI, Joydebpur, Gazipur, Bangladesh. The Chief Scientific Officer of RS provides financial support and cooperation.

CONFLICTS OF INTEREST:
The authors state that they don't appear to have any friction of part related to the study.