Активность

To explore the effects of future climate change on food production in Henan Province, the climate potential productivity and its change characteristics in Henan Province were calculated by agro-ecological zone (AEZ) model. This study was based on the production potential and climate resource carrying capacity of summer maize and winter wheat, combined with the observation data of 111 meteorological stations in Henan Province from 1961 to 2017 and the meteorological data under two emission scenarios of RCP4.5 and RCP8.5 in 2041-2080. With the grain demand index under different living standards, we analyzed climate carrying capacity and surplus space of Henan Pro-vince. The results showed that the average climatic potential productivity of maize was 18408.87 kg·hm-2 from 1961 to 2017, with high values in the middle and east, and low values in the west. Compared with the reference period (1981-2010), climatic potential productivity of maize under RCP4.5 and RCP8.5 decreased by 13.0% and 8.0% respectively, with tod, the relative residual rate of climate resources in the future would reduce nearly 40%.To reveal the spatio-temporal variation characteristics of apple’s phenology and their critical response time period and intensity to the temperature change in the main production areas of northern China, we chose Fushan, Wanrong and Akesu to respresent the Bohai Gulf, the Loess Plateau and Xinjiang apple production areas, respectively. Apple’s phenology data of buds opening (BO), first leaf unfolding (LU), first flowering (FF), fruit maturing (FM), end of leaf coloring (LC) and the end of leaf fall (LF) at the three stations during 1996-2018 were used to analyze the changes of phenological occurrence dates and different growth stage lengths. Partial least squares (PLS) regression was applied to identify the impacts of climate warming on different phenology events at daily resolution. Results showed that regional mean occurrence dates of apple’s BO, LU and FF advanced by a rate of 0.36, 0.33 and 0.23 day per year, respectively. However, apple’s LF postponed by 0.68 d·a-1. The FM and LC showed different trendsst influence in Fushan. Our results could provide theoretical basis for response to climate change for apple industry in different areas of China.Understanding the response mechanism of soil aggregate-associated organic carbon (OC) and nutrients to tea cultivation age can lay a theoretical foundation for improving soil fertility, ensuring soil health, and promoting sustainable utilization of soil resources in the tea plantations. In this study, concentrations of soil OC and nutrient were analyzed in >2, 2-1, 1-0.25, and 2 mm fractions, and were 18.65 and 0.80 g·kg-1 in the 2-1 mm fraction. Soil aggregate-associated available nitrogen (AN), available phosphorus (AP), and availa-ble potassium (AK) concentrations were highest in the less then 0.25 mm fractions with mean values of 50.43, 23.06, and 68.04 mg·kg-1, respectively. Long-term tea cultivation was favorable to the accumulation of soil OC, TN, AN, and AP, whereas the accumulation rates of these element stocks in the whole soil decreased with increasing tea cultivation age. SKI II nmr In contrast, soil AK was susceptible to leaching in tea cultivation, with the loss rate of this element stock in the middle stage (from 17 to 25 a) being higher than those in the other stages. To ensure soil quality and promote the sustainable utilization of soil resources, more attention should be paid to the problems such as the decrease of soil aggregate stability and the aggravation of AK loss after 17 a of tea cultivation.The variations of water potential gradients through the soil-plant-atmosphere continuum (SPAC) are of great significance to reveal the responses of plant water use to environmental changes. We conducted a continuous experiment to monitor the potentials in the near-canopy atmosphere (Ψair), soil (Ψsoil) and plant xylems (Ψstem) during the growing season in an apple orchard located in the Loess Plateau. The results showed that the average Ψstem during the growing season ranged from -0.24 to -2.0 MPa, with a mean value of -0.57 MPa. The average water potential gradient in soil-plant-atmosphere system was 19.81155 (ΨsoilΨstemΨair). We found a significant positive linear correlation between the ΨstemΨsoil gradient and volumetric soil water content (VWC, %). The Ψstem was more strongly correlated with Ψsoil than Ψair. Moreover, the sensitivity of Ψstem to Ψsoil decreased when Ψsoil was lower than -0.08 MPa which corresponded to VWC=17%, 0.56 times of field capacity. This was reflected by the increased linearity between Ψair /Ψstem and Ψsoil as Ψsoil decreased. There was a threshold effect for the relationship between Ψair and Ψstem. That is, the Ψstem in a day increased with the increasing of Ψair before the latter reached -69 MPa, after which the Ψstem decreased. The decline of soil water content caused an obvious decrease in water potential gradient through the SPAC system, and the threshold effect existed when VWC was below 17%. The results provide a basis for understanding the mechanisms of plant water in response to soil and atmospheric drought.To clarify the spatial variability of soil water content at field scale, a reasonable sampling method was established to support precision irrigation in the field. Soil samples were collected from Caoxinzhuang experimental area in Yangling District, Shaanxi Province at seven different dates. The spatial variation of soil water content in different soil layers of 0-60 cm were analyzed with classical statistics and geostatistics methods. The results showed that spatial distribution of soil water content in field scale was weak and moderate. When soil water content was within the range of 11.7%-20.1%, soil water content was negatively correlated with spatial variability. Sampling interval signifi-cantly affected the calculation accuracy of the spatial variability of soil water content. The coefficient of variation of soil water content between the east-west direction spacing of 27 m and the north-south direction spacing of 9 m was about 3.3% higher than the east-west direction spacing of 9 m and the north-south direction spacing of 18 m.