Document Type : Research Article
Abstract
Abstract: Wheat (Triticum aestivum L.) is considered one of the world's most important
cereal crops. Every year 704 million tons of grain is produced worldwide. Bread wheat
croplands cover 17% of the total crop area. In recent years, sudden changes in air
temperatures have a negative impact on the morphological, physiological, biochemical and
molecular properties of wheat and grain yield. Therefore, it is important to create highyielding
and resistant varieties of bread wheat to abiotic factors and to develop its primary
source in the condition of different regions. In the result of this study, the influence of
high temperature which varied from 30°С and above continuously during spiking and
maturation period of grain, especially in the period of grain filling, on grain quality and
productivity has been studied thoroughly for southern parts of Uzbekistan. Mostly, winter
bread wheat varieties are grown in these southern regions. The optimal sowing time in
autumn season is the second decade of October. In order to determine the heat resistance
of the winter wheat varieties that are mostly grown in the Republic and selected in the
result of breeding, the experiments and observations were carried out on optimal and late
sowing periods. The optimal planting time was found to be appropriate on the 15th of
October and for late sowing the 15th of November. At the same time, late sown varieties and
samples are divided into resistant and non-resistant groups due to the delay in the
maturation period and greater exposure to heat. At the study, temperatures during the
growth period were calculated and daily temperatures during the grain filling period were
determined too, and the influence of air temperature on growth phases, height of plant
(cm), spike length (cm), number of spikelets in a spike (pieces), grain weight in a spike(g),
weight of 1000 grains (g), grain nature (g/l), protein amount (%), gluten amount (%), its
changes and the results in optimal and late periods were studied by comparing them.
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