Sterntang7169

The average value of habitat quality in the region dropped by 2.7%, whereas the level of habitat degradation increased by 33.4%. The level of habitat quality was unstable, and patches with high-level habitats were easily converted to lower level. The conversion rates of Lanzhou, Xi'an-Xianyang and Taiyuan were 12.9%, 2.9% and 1.7%, respectively. There were eight influencing factors that could effectively explain the spatial variation of habitat quality (R2=68.7%). Among those factors, population density and distance to roads were the main factors for the fragmentation of habitats, while slope, GDP and precipitation had positive effects on the optimization of habitat spatial patterns.It is objective needs during utilization and management of regional cultivated land resource to use remote sensing to accurately and efficiently retrieve the status of cultivated land fertility at county level and realize the gradation of cultivated land rapidly. In this study, with Dongping County as a case, using Landsat TM satellite imagery and cultivated land fertility evaluation data, the moisture vegetation fertility index (MVFI) was constructed based on surface water capacity index (SWCI) and normalized difference vegetation index (NDVI), and then the optimal inversion model was optimized to obtain the best inversion model, which was further applied and verified at the county scale. The results showed that the correlation coefficient between MVFI and integrated fertility index (IFI) was -0.753, which could comprehensively reflect the growth of winter wheat, soil moisture and land fertility, and had clear biophysical significance. The best inversion model was the quadratic model, with high inversion accuracy. This model was suitable for the inversion of cultivated land fertility in the county. The spatial distribution and uniformity of the inversion results were similar to the results of soil fertility evaluation. The area differences between the high, medium and low grades were all less than 2.9%. This study provided a remote sensing inversion method of cultivated land fertility based on the feature space theory, which could effectively improve the evaluation efficiency and prediction accuracy of cultivated land fertility at the county scale.Multiple agrometeorological disaster (MAD) occurs simultaneously in maize production. In order to ascertain the occurrence regularity and characteristics of MAD of maize in Liaoning Pro-vince, we defined and classified MAD, identified MAD of 50 meteorological stations in the maize growing season of Liaoning Province from 1961 to 2017, and examined the effects of MAD on maize yield in typical years. The results showed that the occurrence range of MAD was higher in most years from 1961 to 2017 than that of single agrometeorological disaster (SAD), and that the occurrence frequency of MAD was higher in most areas than that of SAD. The major MAD in Liaoning Province was drought in multiple periods (M1-D), followed by the combination of drought and delayed cold damage (M2-DC). The occurrence range of M1-D showed an upward trend from 1961 to 2017, whereas other MAD types showed a downward trend. After analyzing the occurrence of MAD in the typical years of maize yield reduction, we found that the occurrence frequency of M1-D and M2-DC was higher.Strawberry variety 'Benihoppe' was used as the experimental material. The temperature treatments were set at 32 ℃/22 ℃, 35 ℃/25 ℃, 38 ℃/28 ℃ and 41 ℃/31 ℃ (daily maximum temperature/daily minimum temperature), and the stress days lasted for 2, 5, 8 and 11 d, with 28 ℃/18 ℃ as the control. We measured the photosynthetic characteristics, chlorophyll fluorescence characteristics, reactive oxygen species, protective enzyme activity and membrane lipid peroxidation of strawberry under different high temperature treatments. The key indices were extracted by principal component analysis. The high temperature stress index (Z) was defined to divide the high temperature stress grade. check details The results showed that 1) with the aggravation of high temperature stress and the extension of stress time, chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoid (Car), light saturation point (LSP), maximum net photosynthetic rate (Pmax), apparent quantum efficiency (AQE) and maximum photochemical efficiency (Fv/Fm) decreased, while lig(4 less then Z). The results would be helpful for the prevention of strawberry high temperature disaster and the optimization of microclimate environment.In order to clarify the effects of foliar spraying the solution with low concentration NaCl on the growth and matter accumulation of vegetables under the temperature-regulated solar greenhouse, we carried out an experiment on cucumber seedlings with two cotyledons, under two tempera-ture regimes and four concentrations of NaCl. Low-medium temperature zone (L) and medium-high temperature zone (H) were set by low tunnel with plastic film in the greenhouse. The solutions with different concentrations of NaCl, 0 mmol·L-1 (L0 and H0), 5 mmol·L-1 (L5 and H5), 10 mmol·L-1 (L10 and H10) and 15 mmol·L-1 (L15 and H15), were sprayed every day to the cucumber seedlings. The seedling growth, plant biomass, nutrient accumulation and photosynthetic gas exchange parameters of cucumber seedlings were measured at the 21th day of spraying treatment. Compared with the control groups (L0 and H0), NaCl spraying significantly increased dry matter and plant water content by 38.6% (L5)-50.2% (L10) and 20.8% (L5)-52.2% (L10) in L zone NaCl concentration in affecting plant water content, SI, gs and free amino acid content (except leaf). In conclusion, foliar spraying with 5-10 mmol L-1 NaCl could promote growth and physiological indices of cucumber seedlings, with the effect being higher under low temperature regime. More importantly, foliar spraying of proper concentration (L5 and H10) of NaCl could stimulate biomass accumulation more than water retention in cucumber seedlings, which would provide a relevant breeding target for high water-use efficiency in cucumber.Water shortage and soil salinization are two main limiting factors for cotton production in southern Xinjiang. We examined the effects of soil matrix potential (SMP) regulation at various growth stages on cotton growth, soil water and salt distribution, to provide theoretical basis for water saving, salts control, and efficient production in cotton fields. The mulched drip irrigation experiments were conducted to monitor cotton growth, aboveground biomass, cotton yield, soil water and salt distribution and other indicators. Three SMP thresholds, i.e.,W1(-20 kPa), W2(-30 kPa) and W3(-40 kPa) were set at the seedling stage (A), seedling stage + budding stage (B), and seedling stage + budding stage + flowering stage (C), with SMP of -50 kPa at 20 cm soil depth below the emitter as the CK. The results showed that plant height, leaf area index (LAI) and aboveground biomass followed the order of WC>WB>WA>CK, when SMP were changed at various growth stages. Plant height, LAI and aboveground biomass increased with increasing SMP thresholds, with the values under W1C and W2C being significantly higher than the other treatments.