In order to explore the possible physiological mechanism of high temperature induced sterility in rice, we examined the floret sterility and endogenous plant growth regulator contents in pollens of two hybrid rice cultivars Shanyou63 and Teyou559 that are tolerant and susceptible to high temperature, respectively. Indexes of floret sterility, pollen activity, and variation of endogenous indole-3-acetic acid (IAA), gibberellic acids (GAs), abscisic acid (ABA), free proline and soluble proteins in anthers were measured. We found that during the course of high temperature treatment, both cultivars exhibited a marked decrease in pollen activity, pollen germination and floret fertility; however, the high temperature tolerant Shanyou63 showed a much slower rate of decrease than the high temperature susceptible Teyou559. In addition, anthers of both cultivars displayed a decrease in the contents of IAA, GAs, free proline and soluble proteins but an increase in the ABA content. Yet compared to Teyou559, Shanyou63 retained significantly higher levels of free praline and GAs and a lower level of ABA, along with higher pollen vigour and pollen germination rate even after prolonged high temperature treatment. Our study suggests a possible correlation between pollen viability/floret sterility and high temperature-caused changes in IAA, GAs, ABA, free proline and soluble protein contents. The severity in these changes may reflect the variation of rice cultivars in their heat stress sensitivities for floret development.

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The objectives of developing optimum leaf area index dynamic models for rape (OLAIDM) was to develop Rape Cultivation Simulation-Optimization-Decision Making System(Rape-CSODS) , to design its planting , to regulate and control its growth and development, and to fulfill its high yield, good quality, high benefits and standard production eventually. The OLAIDM were developed based on field experiments with 3 cultivars, 6 sowing dates, 2 types of plant pattern and 4 sites from 2002 to 2007 in middle and lower valley of Yangtze river in China and relative data from references of rape researches, employed ideas of R/WCSODS (Rice/Wheat Cultivation Simulation-Optimization-Decision Making System), and in the same time, the OLAIMR and its parameters also were assessed, calibrated and tested. The average absolute deviation(de), correlation coefficients(r) and the standard errors of their absolute deviation(Sde) of between the observed and simulated values for LAI of two cultivars in Wuhan and Nanjing were -0.03~0.1533, 0.9707~0.9997 and0.1332~0.4032, respectively. 1:1 line of them were in Fig. 1 to 4. Multi-factors such as the ramification types, cultivars, and light et al. were taken into account in this study, therefore, the OLAIDM with general Please use the following format when citing this chapter:

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