Studies On Growth Charactteristics And The Mechanism Of Drought Tolerance In New Wheat Cultivar Zhengmai 1

It is important to elucidate the growth and development characteristics and mechanism of drought tolerance in wheat for breeding cultivar and optimizing cultivation technology. Field experiments were conducted at Luoyang area using a new wheat cultivar Zhenghan 1 with good drought tolerance and Yumai 2 and Yumai 42 as control to synthetically study the effects of different drought conditions on wheat growth, yield formation and physiological characteristics in leaves and roots, and to investigte the tolerance mechanism to drought. The results were showed as below.The root system of Zhenghan 1 was developed slower at former developing stage and faster at middle stage than that of Yumai 2. Before returning green, the leaf emergence rate of Zhenghan 1 was almost as the same as that of Yumai 1, while after returning green, the leaf emergence rate was little faster than that of Yumai 2, but the flag leaves of Zhenghan 1 spread relatively later. Zhenghan 1 had high tillering ability, and more earring number but it had lower percentage of earbearing tillers. In addition, the start and end time of young spike differentiation of Zhenghan 1 was relative later, but the duration of spike differentiation of Zhenghan 1 was almost the same as that of Yumai 2. Zhengmai 1 had relatively shorter spikelets differentiation period resulted in fewer the number of differentiated florets. Nevertheless, Zhengmai 1 had longer grain filling duration and stable grain filling process resulted in relatively higher 1000-grain weight due to longer development period.Integrated soil column bagging in field and small rain shelter being applied, two factors of soil moisture before sowing and simulation rainfall in growth and development stages and three levels of rain amount were set. The growth and development of root system and the plant development of Zhenghan 1 in the different drought levels were studied. It revealed that root system of Zhenghan 1 distributed mostly in soil layer of 0 to 40 centimeter, which accounted for 69.52% of total root system dry weight and the treatment of drought plus drought was the highest to 72.0%. Root system weight in soil layer of 40 to 120 centimeter in average was 22.5% of total root system dry weight, and the treatment of average plus average was the highest to 23.8%. The root system also distrusted in soil layer of 120-200 centimeter and its weight in average was 7.98% of total root system dry weight, and the treatment of average plus enough was the highest to 10.2%. Root /shoot ratio of the treatment of drought plus drought reached the highest value to 0.147, and the treatment of enough plus enough was the lowest to 0.088. There was marked difference between these two treatments. Water use efficiency of the treatment of enough plus enough...