STUDIES ON HIGH-YIELDING RULES AND MEASURES IN SPRING WHEAT——An Analysis of Yield components
Li Wen-xiong Zeng Han-bing(Department of Agronomy)
Relationships between yield components were analyzed in this paper with the data obtained from experiments under the subject of "Studies on High-Yielding-Rules and Measures in Spring Wheat" carried Out in Heilongjiang Province since 1975. The results showed that under the case of high-yielding level, as spikes per unit area reached a certain range (650-750 spikes/m~2 in the studies), the key of increasing yield continuously is to raise the productivity of spike and kernels per unit area. To increase kernels per unit area plays an important role in raising grain yield. The close relationships between kernels per unit area, kernel, weight/spike as well as 1000-grain weight and grain yield were found. There were also significant positive correlations between total spikelets, fertile spikelets and kernels per spike. According to the characteristics of both climate and. wheat development in the locality, it is necessary to develop cullivars with larger differentiated intensity of spikelet primodia, i. e. differentiating more spikelet primodia per unit time, and with more spikelets per spike on the one hand, and to increase the percentage of fertile spikelets per spike by means of increasing total spikelets per spike and their fertility with cultural practices on the other hand, and the latter is very important to the spring wheat of the locality. Regression analysis indicated that kernels per spike and 1000-grain weight were both closely correlated with kernel weight per spike, but T values in regard to the relationship between kernels per spike and kernel weight per spike were higher than that of between 1000-grain weight and kernel weight per spike regardless of genotypes and years as well as cultural practices used. The coefficients of variation of kernels per spike in different crop seasons, evironmental factors and cultivars were larger than that of 1000-grain weight. Also, the calculation of contribution of kernels per spike and 1000-grain weight to spike productivity increase showed that kernels per spike played a more important role than kernel weight. Therefore, in increasing kernel weight per spike, it is necessary to develop cultivars with characters of higher 1000-grain weight,highe intonsity of grain filling in both full and early filling period, and shortet grain filling duration.The rofe of cultural practices is mainly to ensure the realization of genetic potential of kernel weight.