Study of Yield and Yield Components of Wheat (Triticum aestivum L.) Genotypes at Grain Filling Stage under Heat Regimes

A field experiment was conducted with wheat genotypes Halna, PBW 343, NW 1014, DBW 16, K 911 and AAI 11 during rabi 2015-16 at the student instructional farm of Narendra Deva University of Agriculture and Technology, Kumarganj, Faizabad (U.P). Heat treatment was given by delayed sowing of 65 days (25 January) than normal date of sowing (23 November 2015). So, that wheat genotypes could experience severe heat stress at grain filling stage. The screening of wheat genotypes was done on the basis of plant height, tiller number per plant, days to 100% flowering, days to 100% maturity, stay green duration, number of spikes per plant, spike length, number of grain per spike, test weight and yield plant -1 at grain filling stage. The wheat genotypes Halna, NW 1014, DBW 16, K 911, and AAI 11 had high membrane stability index (MSI) and stay green duration also showed less percent reduction in yield and yield components comparatively PBW 343 and DBW 16. Therefore, MSI and stay green duration can be used as physiological screening indices for heat tolerance genotypes at grain filling stage. Key world: MSI, Stay green duration, Wheat, Heat stress, Yield components. Research Article Cite this article: Jaiswal, B. , Prasad, S. , Dwivedi, R. , Singh, S. , Rani, R. , Shrivastava, S. , Kumar, A. and Yadav, R.K. , Study of Yield and Yield Components of Wheat (Triticum aestivum L.) Genotypes at Grain Filling Stage under Heat Regimes, Int. J. Pure App. Biosci. 5(4): 331-340 (2017). doi: http://dx.doi. org/10.18782/2320-7051.3069 Jaiswal et al Int. J. Pure App. Biosci. 5 (4): 331-340 (2017) ISSN: 2320 – 7051 Copyright © August, 2017; IJPAB 332 Heat stress reduces the stay green duration by accelerating senescence process. The early leaf senescence reduces the photosynthesis process at vegetative stage and limit reserved photosynthates for future growth. There is genetic variability in wheat varieties for heat stress tolerance. Heat sensitive varieties show more reduction in yield and yield attributing traits as compared to heat tolerance 10 . Late planted wheat suffers drastic yield losses which may exceed to 40-50%. In response to higher temperatures flowering and ripening are accelerated with a significant reduction in the number of days to the boot stage, heading, flowering and maturity. Stress may also be critical when it occurs during grain filling, as it may result not only in a reduction in the extent of grain filling 17 , but also in more rapid cell death and in the earlier occurrence of harvest ripeness 1 . Wheat is highly sensitive to heat stress and even slight variation in temperature during critical stages like pollination and milky ripe reduces the quality and quantity of wheat grains. Increase in temperature of 1oC reduce the yield of wheat by 4% 8 . High temperature shortens the grain filling period significantly in all the bread and durum wheat genotype because of significant interaction of each genotype with temperature 9 . Stay green is a trait that has been used to indicate heat tolerance in hot environment. Wheat genotypes that had high Membrane stability index and stay green duration at grain filling stage are considered for heat tolerance and it uses as physiological indices for screening tolerant wheat varieties. The selection of heat tolerance wheat varieties by Membrane stability and stay green duration approaches for developing high yielding heat tolerance wheat varieties through wheat breeding programme is major concerned of this paper. MATERIAL AND METHODS Six wheat genotypes Halna, PBW 343, NW1014, DBW16, K-911 and AAI11 were sown at student instructional farm of Narendra Deva University of Agriculture and Technology Kumarganj, Faizabad in rabi season 2015-16. The treatment of heat stress was given by very late sowing of 60 days (25 January) than normal date of sowing (15 November, 2015). So that wheat genotypes could experience severe heat stress at grain filling stage. The temperature at the time of grain filling stage varied from 35 to 38 0 C in very late sown wheat crop. Days to 100% flowering was recorded from date of sowing to 50% flowering. Days to 100% maturity was recorded by continuing days from sowing to 100% physiological maturity of five plants and average out to one as considered 100% maturity. Days to stay green duration was recorded from 100% greenness to reduction of greenness start. Plant height were recorded from base of plant to base of spike of five plants and average out to one. Tiller number of five plants were recorded separately and average out to one. Number of spikes of five plants were recorded and average out to one as spike plant -1 . Main Spike length of five plant were recorded and average out to one as spike length. Membrane stability index(MSI) were recorded in control verses treatment at the grain filling stage by the method of Sadalla et al 19 . Number of grain spike 1 were recorded by selecting main spike of five plants and average out to one as considered grains spike -1 . Grain yield of five plants randomly selected were taken at maturity and average out to one as grain yield in gram per plant. Test weight was recorded by randomly counting 1000 seeds and weighted in gram as test weight per plant. Jaiswal et al Int. J. Pure App. Biosci. 5 (4): 331-340 (2017) ISSN: 2320 – 7051 Copyright © August, 2017; IJPAB 333 RESULT AND DISCUSSION Fig. 1: Effect of heat stress on Plant height (cm) of wheat genotype under stress condition Wheat genotypes showed genetic variability in plant height. Heat stress significantly reduced the plant height under very late condition (Fig.1). In irrespective genotypes, more reduction was noted significantly high in very late in comparatively timely sown condition. High reduction was recorded in PBW 343 (50.64%), DBW 16 (32.2%), K 911 (31.65%), while low in Halna (24.36%), NW 1014 (28.57%), and AAI 11 (30.72%) under heat over normal condition. If temperature conditions are unfavorable, the physiological processes may be defective, with negative consequences for both vegetative and generative developmental processes and even height . Fig. 2: Effect of heat stress on number of tillers per plant of wheat genotypes under heat stress condition The number of tillers in wheat genotypes showed significant variability (Fig.2). High temperature reduced the No. of tillers under very late sown condition. In all these genotypes, more reduction was recorded in PBW 343 (43.74%), DBW 16 (35.0%), AAI 11 (32.0%), while low in Halna (20.0%), NW 1014 (25.0%), K 911(30.0%) under very late condition. The elevation temperature during formation of tillers decrease the numbering of tiller formation. The temperature is of key importance for plant development, influencing the rate of tillering, the appearance of the nodes, flowering and even grain filling. Each phenophase has a specific temperature range within which it takes place normally to the benefit of the whole plant 14 . 0 20 40 60 80 100 120 140 160 Halna PBW-343 NW-1014 DBW-16 K-911 AAI-11 P la n t h ig h t (c m ) Wheat genotypes % Reduction