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Incorporating oilseed-rape straw in soil is one of the effective methods for enhancing the use efficiency of agricultural resources in the rape-rice rotation system. However, the impacts of oilseed-rape straw incorporation on root growth and dynamic changes in soil are still unclear. In order to provide a deeper understanding of the oilseed rape straw return on rice growth and productivity, the experiment was conducted in the field and in a specially-designed pots system from 2016 to 2017 by means of two straw returning methods and four straw returning amounts. In the early stage of rice growth (0&ndash, 36 days after rice transplanting) the straw returning treatments decreased 1.0&ndash, 8.6 mg/plant in bleeding density and 0.10&ndash, 6.11, 0.06&ndash, 0.31, and 0.52&ndash, 0.84 &mu, mol/(g h) in the activity of glutamine synthetase (GS), glutamic-oxalacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT), respectively. Oilseed rape straw returned by mulching induced negative impacts on new germinating roots in 0&ndash, 10 cm of soil, while the negative impacts were observed on roots in 10&ndash, 30 cm of soil for straw returned by plowing. In the later stage of rice growth (56&ndash, 75 days after rice transplanting), oilseed rape straw returning produced some positive impacts on rice roots, which enhanced the yield of rice. Conclusively, our findings suggested that dynamic root growth and the activity of root enzymes are two major factors behind the slow reviving of rice after transplanting in the straw returning field. Plowing is a more appropriate method of straw returning than mulching in the rape-rice rotation system in the Sichuan basin area, with a straw incorporation rate of 3.0 t/hm2.

Drought is one of the major factors limiting rice yield worldwide. A total of 46 hybrid rice varieties were chosen to investigate their root distribution and their response to drought. A field experiment was carried out in a dry shed building to evaluate the drought tolerance capacity of hybrid rice varieties on the basis of CTIRDE (complex tolerance index of rice under drought environment) values. Next, the experiment was conducted in a specially designed pot system and seed bags to analyze the root distribution and activity of antioxidant enzymes in different rice varieties. Moreover, the DEEPER ROOTING 1 (DRO1) gene was sequenced to elucidate its role in the root distribution of typical rice varieties. On the basis of CTIRDE values, the 46 hybrid rice varieties were classified as tolerant (CTIRDE &ge, 0.75), semi-tolerant (0.75 &gt, CTIRDE &gt, 0.65), or sensitive (CTIRDE &le, 0.65) to drought stress. The tolerant varieties (Chuanguyou208 and Deyou4727) displayed a significantly larger length, had higher number and weight of roots in the 30&ndash, 50 cm soil layer, and exhibited a significantly higher activity of Superoxide dismutase (SOD) and Peroxidase (POD) enzymes in roots during the drought stress period. The DRO1 gene sequencing results revealed that the tolerant and sensitive varieties exhibited a single-nucleotide polymorphism (SNP) in the 3-exon region, and the tolerant varieties (Chuanguyou208 and Deyou4727) exhibited a larger root growth angle with the horizontal axis, hence developing a deeper root system as compared with the other two group varieties. A significant correlation was found not only between the DRO1 gene and root distribution but also between DRO1 and the activity of SOD and POD enzymes. Conclusively, as a key feature, a deep root system enabled tolerant rice varieties (Chuanguyou208 and Deyou4727) to avoid drought stress by absorbing more water stored in deep soil layers. The root distribution, activity of POD and SOD enzymes in roots, and DRO1 gene can be used to screen tolerant rice varieties that can survive better under drought stress during the seedling stage of rice growth.

Understanding the influences of rainfall and temperature on soil water and the grain production of winter wheat (Triticum aestivum L.), is of great importance to ensure the sustainability of food production on the Loess Plateau of China. Based on calibration and evaluation, the Environmental Policy Integrated Climate (EPIC) model was employed to determine the response of soil water and winter wheat to rainfall and temperature changing over the last 30 years in different regions. Results showed that (1) the EPIC model simulated soil water content well in 0&ndash, 2 m soil, with a relative root mean square error (RRMSE) value of 6.0~14.0%, and the mean value of R2 was 0.824, which was similar to the value of ME (0.815), (2) rainfall decreased 13.6&ndash, 24.9% more from 2001 to 2010 than it did during 1961&ndash, 2000, while its minimum and maximum temperature increased 1.00&ndash, 1.55 &deg, C and 0.30&ndash, 0.84 &deg, C respectively, in comparison with 1961&ndash, 2000, (3) both the increase of maximum temperature and the decrease of rainfall were harmful to the production of winter wheat. Contrarily, the increase of minimum temperature was beneficial to the production of winter wheat on the Loess Plateau of China. Furthermore, due to rainfall decreasing, the winter wheat yield of Luochuan, Changwu, Yuncheng, and Yan&rsquo, an decreased by 8.5%, 7.6%, 11.7%, and 12.3%, respectively. Because of the rising of the maximum temperature, winter wheat yield decreased 6.4%, 6.8%, 7.2%, and &minus, 3.0%, respectively. On the other hand, the increase of the minimum temperature raised the winter wheat yield of 8.8%, 10.2%, 1.5%, and 12.0%, respectively. Climate change, either precipitation reduction or temperature increase, decreased soil water in the dry land winter wheat field. Therefore, more water-saving technologies are needed to adapt to climate change, to store and use water sources more effectively in semi-arid regions. Though precipitation reduction and maximum temperature increase produced negative impacts on winter wheat yield, the uptrend in minimum temperature is better for increasing the winter wheat yield, which can be used by farmers and governments to adapt to climate change, by adjusting planting time properly.