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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:

The SPAD‐502 chlorophyll (Chl) meter and the Dualex device can estimate crop N status based on the measurement of leaf Chl concentration and polyphenolics (Phen) concentration, respectively. However, soil water status may confound such assessment of N status. This study compared the sensitivity of SPAD, Dualex, and SPAD/Dualex ratio as indicators for assessing corn (Zea mays L.) N status and the influence of soil water content (SWC) on the indicators in their absolute and nitrogen sufficiency index (NSI) expression. A greenhouse trial was conducted with five N fertilizer application rates (0, 50, 50+75, 50+150, and 200 kg N ha−1) and three SWC levels (high, medium, and low). A field trial also was performed with six N rates (0, 20+40, 20+80, 20+120, 20+160, and 250 kg N ha−1) and spatially variable SWC as a covariate. The responses of SPAD, Dualex, SPAD/Dualex ratio (and their corresponding NSI) to N rates and SWC levels were compared. The results showed that SPAD, Dualex, and SPAD/Dualex ratio were all influenced significantly by N rates and by SWC levels. When expressed as NSI, however, the parameters' relationships with N were essentially decoupled from SWC. The NSISPAD was more affected significantly by interactions among N, SWC, and DAS (days after sowing) than were 1/NSIDualex and NSISPAD/Dualex. The latter showed a greater sensitivity to N fertility levels than the other indicators, resulting in a better discrimination of N treatments and under variable SWC conditions in the two trials.

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During the period of senescence of desert plant Alhagi sparsifolia Shap. the maximum photochemical quantum yield measured as variable to maximum fluorescence ratio (F v /F m ) remained relatively high, although the number of active reaction centres per cross section (RCs) decreased significantly. The efficiency of electron acceptors beyond the primary quinone acceptor (Q A ) decreased. The effect of temperature and irradiance on photosystem activity was maximum after 6 d. Our results suggest that: 1) the down-regulation of photosystem activity was due to the decline of both RCs and electron acceptance between plastoquinone (PQ) and cytochrome (cyt) b6/f; 2) photosystem activity presented negative correlation with daily mean temperature, and 3) reduction of daily sunshine period and increase of temperature at noon can stimulate the speed of senescence.