Study On Morphological Characters Of High-Yielding Rice Varieties And Discuss On Characters Of Plant Type In Upstream Of Yangtze River Under High Temperature And Summer Drought

The upstream of Yangtze River is one important area where is the main habitat of hybrid rice in China. In this area, containing Chongqing, east and south of Sichuan province, it is disadvantageous to the harvest of rice that the frequency natural disaster of high temperature and summer drought in later period of rice birth. This kind of special environment also has the disadvantageous influence to the work of high-yielding hybrid rice breeding. According to the achievement of high-yielding hybrid rice breeding in the upstream of Yangtze River under high temperature and summer drought already, and the problems which is appearance in practice, we selected 9 high-yielding varieties (combinations) which had achieved good yield in recent years in this area for this experiment: No.8 Yifeng, L1A/527, Gang-you725, 1178A/8258, Yu-you600, II-you602, L1A/527, No.9 Q-you with Shan-you63 as comparison variety. We observed plant type traits, physiological characteristics, the production of dry matter, lodging resistance, et.al of the 10 varieties in this area in 2006. We have got some conclusion through the comparison between different varieties in the characteristics above. Such as:①We can infer that the appropriate plant type with high-yielding named"Compact Type in Uppermost 3 Leaves"in this area may be described as: plant height is 128cm±7cm, flag leaf angle is 12.5±2.5o, flag leaf length is 42cm±5cm, relative flag leaf site is 75%±5%, 2nd leaf angle is 17±3 o, 2nd leaf length is 53cm±5cm, relative 2nd leaf site is 50%±5%. The varieties which follow the"Compact Type in Uppermost 3 Leaves"have advantages in area of uppermost 3 leaves, chlorophyll contents in early stage, specific leaf weight, leaf activeness in later stage the EMR(Export rate of matter) and APR(Apparent transformation rate) et.al.②Compared with the lower yield varieties, the research obtains that the high-yielding varieties can increase their chlorophyll contents and specific leaf weight faster, reduce more slowly. They produce more dry matter before heading stage and all their life, but less in later stage. It is the most important reason in yield components why some varieties can achieve higher yield that they have more grains per panicle. The relationship between biological yield and harvest index is negative obviously.③There are 4 classifications of all varieties according to the breaking resistace and length of basal internode. The varieties with longer basal internode and weaker breaking resistance may lodge more easily. And there are other traits of basal internode can influent the lodged index such as area of oval cross, wall thickness, area of wall section, center of stem gravity and the speed of sheath activeness reduction, culm length et.al.