[Dynamics simulation on plant growth, N accumulation and utilization of processing tomato at different N fertilization rates].

Three field experiments were conducted to simulate the dynamics of aboveground biomass, N accumulation and utilization of drip-irrigated processing tomatoes at different N fertilization rates (0, 75, 150, 300, 450, or 600 kg x hm(-2)). The results showed that Logistic models best described the changes in aboveground biomass, N accumulation, and utilization of accumulated N efficiency with the physiological development time (PDT). Rapid accumulation of N began about 4-6 d (PDT) earlier than the rapid accumulation of aboveground biomass. The momentary utilization rate of N (NMUR) increased after emergence, reached a single peak, and then decreased. The N accumulation, aboveground biomass and yield were highest in the 300 kg x hm(-2) treatment. The quadratic model indicated that application rate of 349 to 382 kg N x hm(-2) was optimum for drip-irrigated processing tomatoes in northern Xinjiang.

Rice photosynthetic productivity and PSII photochemistry under nonflooded irrigation.

Nonflooded irrigation is an important water-saving rice cultivation technology, but little is known on its photosynthetic mechanism. The aims of this work were to investigate photosynthetic characteristics of rice during grain filling stage under three nonflooded irrigation treatments: furrow irrigation with plastic mulching (FIM), furrow irrigation with nonmulching (FIN), and drip irrigation with plastic mulching (DI). Compared with the conventional flooding (CF) treatment, those grown in the nonflooded irrigation treatments showed lower net photosynthetic rate (PN), lower maximum quantum yield (Fv/Fm), and lower effective quantum yield of PSII photochemistry (ΦPSII). And the poor photosynthetic characteristics in the nonflooded irrigation treatments were mainly attributed to the low total nitrogen content (TNC). Under non-flooded irrigation, the PN, Fv/Fm, and ΦPSII significantly decreased with a reduction in the soil water potential, but these parameters were rapidly recovered in the DI and FIM treatments when supplementary irrigation was applied. Moreover, The DI treatment always had higher photosynthetic productivity than the FIM and FIN treatments. Grain yield, matter translocation, and dry matter post-anthesis (DMPA) were the highest in the CF treatment, followed by the DI, FIM, and FIN treatments in turn. In conclusion, increasing nitrogen content in leaf of rice plants could be a key factor to improve photosynthetic capacity in nonflooded irrigation.

[Simulation model for the development stages of processing tomato based on physiological development time].

After the comprehensive consideration of the effects of temperature and light on the development physiology of processing tomato, the intrinsic development factor (IDF) was introduced, and, through the analysis of the dynamic relationships between the development stages of different type processing tomato and related environmental factors, the simulation model for the development stages of processing tomato was constructed, based on the concept of physiological development time (PDTv). Different years' experimental data about ecological zones, varieties, and planting modes were used to validate the model. The simulated results about the number of days from sowing to seedling emergence, flowering, fruit-setting, maturing, and ending accorded well with the observed ones, the root mean squared error (RMSE) being 1.09, 2.03, 2.05, 2.77 and 2.53 days, respectively, and the prediction accuracy of this model was significantly higher than that of the growth degree day (GDD)-based model, with the corresponding RMSE being 1.90, 6.63, 6.33, 9.36 and 6.84 days, respectively.