RESUMEN
In arid northwestern China, water shortages have triggered recent regulations affecting irrigation water use in desert-oasis agricultural systems. In order to determine the actual water demand of various crops and to develop standards for the rational use of water resources, we analyzed meteorological data from the Fukang desert ecosystem observation and experiment station (FKD), the Cele desert-grassland ecosystem observation and research station (CLD), and the Linze Inland River Basin Comprehensive Research Station (LZD), which all belong to the Chinese Ecosystem Research Network. We researched crop evapotranspiration (ETc) using the water balance method, the FAO-56 Penman-Monteith method, the Priestley-Taylor method, and the Hargreaves method, during the growing seasons of 2005 through 2009. Results indicate substantial differences in ETc, depending on the method used. At the CLD, the ETc from the soil water balance, FAO-56 Penman-Monteith, Priestley-Taylor, and Hargreaves methods were 1150.3±380.8, 783.7±33.6, 1018.3±22.1, and 611.2±23.3 mm, respectively; at the FKD, the corresponding results were 861.0±67.0, 834.2±83.9, 1453.5±47.1, and 1061.0±38.2 mm, respectively; and at the LZD, 823.4±110.4, 726.0±0.4, 722.3±29.4, and 1208.6±79.1 mm, respectively. The FAO-56 Penman-Monteith method provided a fairly good estimation of E Tc compared with the Priestley-Taylor and Hargreaves methods.
Asunto(s)
Riego Agrícola/métodos , Productos Agrícolas/crecimiento & desarrollo , Agricultura , China , Ecosistema , Monitoreo del Ambiente , Transpiración de Plantas , Ríos , Estaciones del Año , Suelo , AguaRESUMEN
The Arabidopsis thaliana ascorbate-deficient vtc-1 mutant has only 30% ascorbate contents of the wild type (WT). This ascorbate-deficient mutant was used here to study the physiological roles of ascorbate under salt stress in vivo. Salt stress resulted in a more significant decrease in CO2 assimilatory capacity in the vtc-1 mutant than in the WT. Photosystem II function in the Arabidopsis vtc-1 mutant also showed an increased sensitivity to salt stress. Oxidative stress, indicated by the hydrogen peroxide content, increased more dramatically in the vtc-1 mutant than in the WT under salt stress. To clarify the reason for the increased oxidative stress in the vtc-1 mutant, the contents of small antioxidant compounds and the activities of several antioxidant enzymes in the ascorbate-glutathione cycle were measured. Despite an elevated glutathione pool in the vtc-1 mutant, the ascorbate contents and the reduced form of ascorbate decreased very rapidly under salt stress. These results showed that the activities of MDAR and DHAR were lower in the vtc-1 mutant than in the WT under salt stress. Thus, low intrinsic ascorbate and an impaired ascorbate-glutathione cycle in the vtc-1 mutant under salt stress probably induced a dramatic decrease in the reduced form of ascorbate, which resulted in both enhanced ROS contents and decreased NPQ in the vtc-1 mutant.
Asunto(s)
Arabidopsis/enzimología , Ácido Ascórbico/fisiología , Cloruro de Sodio/farmacología , Antioxidantes/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Glutatión/metabolismo , Peróxido de Hidrógeno/metabolismo , Proteínas Mutantes/metabolismo , Nucleotidiltransferasas/genética , Nucleotidiltransferasas/metabolismo , Oxidación-Reducción , Estrés Oxidativo/fisiología , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Complejo de Proteína del Fotosistema II/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Agua/metabolismoRESUMEN
According to the occurring frequency and life form of plant species at different altitude levels, this paper studied the changing characteristics of the species a diversity of pasture community at the altitude from 2500 m to 3000 m in Qilian Mountains. The results showed that with increasing altitude, the Shannon-Wiener species diversity index increased from 1.432 to 1.832, and the variety of Simpson index was very complicated. An altitude of 2701-2800 m was an important turning point for species diversity. In pasture community of Qilian Mountains, the percentage of the poisonous and the less edible species exceeded 50%, and their biomass was more than 60% of the total biomass of the community. The biodiversity showed a degraded trend.