Improvement of bread wheat for low water requirements through conventional and mutation breeding [electronic resource].

Includes reference.

Twenty one wheat genotypes evolvod through hybridization and mutation breeding teclmiques at Nuclear Institute of Agriculture, Tando Jam, Pakistan were evaluated under water stress conditions along with four check varieties. Four experiments were conducted in a randomized complete block design (RCBD) with 3 replications using four different irrigation levels. Water stress imposod by withholding irrigation at various criticaJ growth stages of wheat crop, i.e. at tillering, pre-anthesis and post-anthesis etc. Effects of water stress on phenological (days for heading, days for maturity, grain filling period), morphological (plant height. 1000-grain weight. grain yield) and meteorological data on daily minimum and maxim, im temperatures prevailod during crop season were studied. Significant effects of water stress were observod on various yield and yield components. Newly evolvod gcaotypes showed. higher tolerance to water stress and had potentials to produce more grain yield than check varieties. At single irrigation, grain yields rangod between1805 to 3730 kgIha Four genotypes MSH-22, BWS-77, sn and 28/4 produced significantly (P<0.01) higher grain yield than drought-tolerant cbeck variety Margalla-99; .6 than Sarsabz; 20 than Chakwal-86 and all were high yielding than Thori (a vnless variety). Similarly. comparatively greater yields were obtainod with the apdication of two irrigations, i.e., at tillering and preanthesis stage. Most of the test entries showed more impressive performance as compared to the drought tolerant check varieties. Grain yield ranged from 1744 to 4025 kg/ha The 1000- grain weight range 1 from 35.2 g to 48.6 g at two irrigations. The high yielding genotypes 8nshowed less reduction in the 1000-grain weight (48.6 g) and ranked first among all the entries. This genotype has also shown more grain weight at the single irrigation experiment as well; hence possessing more drought tolerance than all other entries.

Summary in Arabic.

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