Zamoraalvarez2004

To verify the accuracy and adaptability of crop growth monitoring and diagnosis apparatus (CGMD) in monitoring nitrogen nutrition index of double cropping rice, we established a monitoring model of leaf nitrogen concentration (LNC) and leaf nitrogen accumulation (LNA) for double cropping rice based on CGMD. Eight early and late rice cultivars were selected and four nitrogen application rates were set up. The differential vegetation index (DVI), normalized difference vegetation index (NDVI) and ratio vegetation index (RVI) were collected using CGMD. Meanwhile, ASD FH2 high spectrometer was used to collect canopy spectral reflectance and calculated DVI, NDVI, and RVI. To verify the accuracy of CGMD, we compared the canopy vegetation indices change characteristics collected by CGMD and ASD FH2. The CGMD-based monitoring models of LNC and LNA were established, which was tested with independent field data. The results showed that LNC, LNA, DVI, NDVI and RVI of early and late rice increased with increasing nitrogenMSE and r of model validation in the range of 0.37-0.89 g·m-2, 6.7%-20.4% and 0.9191-0.9851, respectively. Compared with the chemical testing method, using the CGMD could conveniently and accurately measure LNC and LNA of early and late rice, which had a potential to be widely applied for high yield and high efficiency cultivation and precise management of nitrogen fertilizer in double cropping rice production.We examined the correlation between changes of root morphology and endogenous hormones in intercropping systems of wheat and faba bean under different phosphorus levels by hydroponics. Compared with monocropping wheat (MW), the intercropping of wheat and faba bean (W∥F) significantly increased root length of wheat, reduced root average diameter of wheat, and increased root surface area under the condition of 1/2P (low P) level. At the conventional phosphorus level, intercropping significantly reduced root average diameter of wheat, and increased root length and root surface area. Compared with monocropping faba bean (MF), W∥F significantly promoted the growth of faba bean root and increased root surface area of faba bean. At the level of 1/2P, intercropping significantly increased the content of auxin (IAA), abscisic acid (ABA), sali-cylic acid (SA) and jasmonic acid (JA). At the conventional phosphorus level, intercropping could significantly increase the content of IAA, ABA and JA in wheat root, while no significant difference in the SA content of wheat root between monocropping and intercropping wheat was found. Intercropping could increase the content of ABA and SA in faba bean roots, but did not affect IAA and JA contents of faba bean roots. There was no significant correlation between the contents of endogenous hormones (IAA, ABA, SA and JA) and root morphology (root length, root average diameter and root surface area) of wheat and faba bean roots in wheat or faba bean monocropping system. In wheat and faba bean intercropping system, there was a positive correlation between IAA contents of wheat and faba bean and their root length and root surface area. W∥F enhanced IAA of wheat and faba bean root, which was an important factor driving the change of root morphology in the intercropping system of wheat and faba bean.Both salicylic acid (SA) and hydrogen sulfide (H2S) play an important role in regulating plant growth and development and physiological metabolism under abiotic stresses. As signal molecules, the interaction between them in regulating cucumber photosynthesis under low temperature and low light is still unclear. Here, we examined the regulation and interaction of SA and H2S on photosynthesis in cucumber seedlings under low temperature (8 ℃/5 ℃, day/night) and low light (100 μmol·m-2·s-1). Seedlings were foliar-sprayed with SA, sodium sulfide (NaHS, H2S donor), and their scavenger or biosynthesis inhibitors, respectively. Seedlings treated with deionized water at suitable temperature and light condition were used as the control. The results showed that SA increased the L-/D-cysteine desulfhydrase (LCD, DCD) activities and relative mRNA expression, and consequently promoted the endogenous H2S production. However, NaHS did not affect the activities and gene expressions of phenylalnine ammonialyase and isochorismat was not affected by SA biosynthesis inhibitor paclobutrazol and 2-aminoindan-2-phosphonic acid. check details Our results suggested that H2S, as a downstream signal of SA, was involved in regulating photosynthesis in cucumber seedlings under low temperature and low light.To promote the rational application of nitrogen fertilizer for winter wheat under rice-wheat rotation in the Yangtze River Basin, we examined the effects of nitrogen application rates (0, 120, 210, 300 kg·hm-2, expressed as N0, N1, N2, and N3 respectively) on soil nitrate content, nitrogen balance of soil-plant system and yield. The results showed that soil nitrate content increased with increasing nitrogen application rates. Under different nitrogen application treatments, all the nitrate was significantly transfered to the 60 cm soil layer till jointing stage. After jointing stage, topdressing nitrogen significantly increased nitrate content in 0-40 cm soil layer under N1 and N2 treatments and that in the 0-60 cm soil layer under N3 treatment. Soil nitrate mainly accumulated in the 0-40 cm soil layer in the mature stage. Results from nitrogen balance analysis showed that nitrogen absorption, residue and loss varied across different growth stages of wheat, with the period from overwintering to jointing being the principal time of apparent nitrogen loss. The amount of plant nitrogen accumulation, inorganic nitrogen residue and soil nitrogen apparent loss all positively correlated with the nitrogen application rate. Based on the comprehensive analysis through Coase principle and marginal revenue of environmental economics, the optimum nitrogen application rate for production, ecology and economic benefits of winter wheat under rice-wheat rotation was 250 kg·hm-2, and the ratio of base fertilizer to jointing fertilizer was 55, while the corresponding grain yield was 6840 kg·hm-2.