Differential reaction of wheat cultivars to hot environments

Abstract

Ten to 20 spring wheat (Triticum uestivum L.) cultivars of Israeli origin were grown in three winter (normal) and two summer (abnormal) growing seasons. During the period of emergence to anthesis mean daily temperature was on the average 12°C higher and photoperiod was about 3 h longer in the summer than in the winter. Data was collected on the durations of the periods from emergence to double-ridge (GSI), double ridge to anthesis (GS2) and anthesis to grain maturation (GS3), as well as on yield and yield components.The duration of all developmental stages was reduced by high temperature. While the duration of GS2 was the most thermo-sensitive, it may also have been reduced by the longer summer photoperiod. The effect of photoperiod on GS2 could not be isolated, but the results were interpreted to show that the effect of photoperiod on the duration of GS2 was relatively small.The most heat-affected yield component was number of grains per spikelet and the least affected component was the number of spikes per plant. High temperature reduced grain weight via reduced grain growth duration and not grain growth rate. A general linear regression model of yield on its components revealed that while variation for number of spikes per plant had the greatest effect on yield variation among cultivars in the winter, variation for number of grains per spikelet and spikelets per spike were by far the most important in the summer. Grain weight was the least important component, in this respect, in all seasons. Varieties which sustained the highest yield in hot environments were able to maintain the longest duration of GS2 and the highest number of grain per spike.

Spot blotch and terminal heat stress tolerance in south Asian spring wheat genotypes

“…Heat stress tolerance was evaluated by comparing the grain yield and TKW from normal plots (normal planting, disease protected) with that of heat-stressed plots (late planting, disease protected) (Shpiler and Blum, 1986). Similarly, tolerance to spot blotch was evaluated by comparing the grain yield and TKW from normal plots (fungicide protected, timely planted) with that of spot blotch-stressed plots (without fungicide protection, normal planting).…”

“…Kernel number was unaffected, in contrast to observations made in previous controlled environment studies (Gibson and Paulsen, 1999;Khanna-Chopra and Viswanathan, 1999). This difference could be attributed to the growth stage at which heat stress was present (Shpiler and Blum, 1986). U. R. ROSYARA et al Heat stress during GS3 (anthesis to maturity) mainly affects assimilate availability, the translocation of photosynthates to the grain, and starch synthesis and deposition in the developing grain.…”

Physiological response of wheat seeds grown under NaCl and HgCl2 stress

“…Interestingly, for breeding purposes, the resistance to various stresses may be combined and may create opportunities for better yielding wheat varieties. 14,15 Plant response to stress is a complex phenomenon and wheat has a moderate tolerance to salinity. [14][15][16] In the present study we selected modal weight as the seeds to be used for precisely studying the effect of stress.…”

“…14,15 Plant response to stress is a complex phenomenon and wheat has a moderate tolerance to salinity. [14][15][16] In the present study we selected modal weight as the seeds to be used for precisely studying the effect of stress. Seed germination is said to occur due to the water intake by the seed but it is also said to decrease due to the salt.…”

II. Heat stress in Triticum: kinetics of Cu and Zn accumulation

“…Yet, at a cellular level, although about 80% of cellular enlargement occurs between the end of cellular division and the conclusion of dry matter accumulation (Nicolas et al, 1984), the rate of cellular volumetric augmentation does not compensate the decreasing extent of cellular enlargement (Stone et al, 1995. Caley et al (1990 and Jenner (1994) further confirmed these data, and Shpiler and Blum (1986), working with field trials, also reported that grain maturity develops earlier, producing smaller and shriveled grains, in heat stressed genotypes.…”