Study On Drought-resistance Evaluation System And Genetic Analysis Of Maize

In this paper, thirty-five inbred lines and thirty-eight cultivars were cultivated in sheds and in the field. We studied drought-resistance from seven germination indexes, eight growing indexes, seven physiology indexes and ten yield indexes and established the evaluation system in different periods. We also appraised and selected high-yield inbred lines and cultivars. At the same time, eight inbred lines were used to make 28 hybrids by (1/2) n (n-1) diallel crosses design. As GriffingⅠand Hayman methods were used, combining ability and genetic parameters were estimated and the genetic laws of drought-resistance were researched. The main results of this study were as follows:1. Establishment of drought-resistance evaluation system of inbred lines. According to the results of simple relative analyses, nine indexes selected including germination drought resistance index of seed and relative germination energy under the condition of 20% PEG-6000 drought stress, GDRI and relative germination energy under the condition of 15% PEG-6000 drought stress, relative value of leaf water potential at seedling stage, leaf water conservation, kernel per row, axis weight per plant and weight of 100 grains. They were correlated with drought resistance coefficient or drought resistance index at p≤0.05 and p≤0.01 level. Stepwise regression analyses were conducted between the relative value of nine indexes and drought resistance coefficient and drought resistance index. In addition, according to these indexes and partial relative coefficient, drought-resistance evaluation equation (D value) and evaluation system were established. Using D value equation to evaluate the drought resistance of maize was considered scientifically reliable.2. Drought-resistance identification indexes of cultivars. According to the results of simple relative analyses, six indexes were selected including relative value of leaf water potential at seedling stage, leaf water conservation, length of spike, kernel per row, axis weight per plant and weight of 100 grains, They were correlated with drought resistance coefficient or drought resistance index at p≤0.05 and p≤0.01 level. Stepwise regression analyses were conducted between the relative value of five indexes and drought resistance coefficient and drought resistance index. They were relative value of leaf water potential at seedling stage, leaf water conservation, kernel per row, axis weight per plant and weight of 100 grains.3. Methods of choosing maize cultivars of high yield and drought resistance. It was unreliable in a kind of water stressed condition to choose the cultivars using drought resistance coefficient and the yield under non-stress treatment. In many kinds of water stressed conditions, a new concept, the stressed stability index (SSI), was brought forward to evaluate the drought-resistance capability of cultivars. It was feasible to evaluate and choose cultivars of high yield and drought-resistance using the mean value of yield under non-stress treatment and the mean value of SSI. With this new method, which was easy to be used in breeding, Tian tai 16, Nong da 81, Deng hai 6213, Zhong ke 11 and Xiu qing 73-1 were selected from the 30 cultivars as cultivars of high yield and drought-resistance.4. Genetic analysis on drought-resistance. The GCA variance of drought resistance coefficient and the SCA variance of drought resistance index are to p≤0.01 level. The SCA of drought resistance coefficient and relative value of kernel per row are to p≤0.05 level. The relative value of kernel per row accorded with additive-dominative model. Broad heritabilities of drought resistance coefficient and drought resistance index were comparatively high and adapted to choosing lately. Broad heritabilities of the relative value of kernel per row were comparatively low and adapted to choosing early. Among the three indexes, narrow heritabilities were comparatively low and hereditary efficiency of unadditivity efficiency was principal component.