ABSTRACT
The rice production system is one of the most climate change sensitive agro-ecosystems. This paper reviews the effects of current and future climate change on rice production in China. In recent decades, thermal resources have increased during the rice growing season, while solar radiation resources have decreased, and precipitation heterogeneity has increased. The increasing frequency of high-temperature stress, heavy rainfall, drought, and flood disasters may reduce the utilization efficiency of hydrothermal resources. Climate change, thus far, has resulted in a significant northward shift in the potential planting boundaries of single- and double-cropping rice production systems, which negatively affects the growth duration of single-, early-, and late-cropping rice. Studies based on statistical and process-based crop models show that climate change has affected rice production in China. The effects of climate change on the yield of single rice (SR), early rice (ER), and late rice (LR) were significant; however, the results of different methods and different rice growing areas were different to some extent. The trend of a longer growth period and higher yield of rice reflects the ability of China's rice production system to adapt to climate change by adjusting planting regionalization and improving varieties and cultivation techniques. The results of the impact assessment under different climate scenarios indicated that the rice growth period would shorten and yield would decrease in the future. This means that climate change will seriously affect China's rice production and food security. Further research requires a deeper understanding of abiotic stress physiology and its integration into ecophysiological models to reduce the uncertainty of impact assessment and expand the systematicness of impact assessment.
ABSTRACT
In context of the climate change, major abiotic stresses faced by plants include salt stress and drought stress. Though, plants have similar physiological mechanisms to cope with these salt and drought stresses. The physiological and biochemical response of native plants to the combined application of salinity and drought stresses are still not well-understood. Thus, to investigate the combined effect of salinity and drought stresses, an experiment was conducted on Salsola imbricata with four levels of salinity and four drought intensities under the arid climatic conditions. The experiment was conducted in a randomized complete block design with a split-plot arrangement replicated three times. S. imbricata had been found resistant to different levels of individual and combined salt and drought stresses. S. imbricata survived till the end of the experiment. Salt and water stress did not show any significant effects on shoot weight, shoot length, and root length. The drought stress affected the photosynthetic rate, ion uptake and leaf water potential. However, salt stress helped to counter this effect of drought stress. Thus, drought stress did not affect plant growth, photosynthesis rate, and ion uptake when combined with salt stress. Increased Na+ and Cl- uptake under the salt stress helped in osmotic adjustment. Therefore, the leaf water potential (LWP) decreased with increasing the salt stress from 5 dSm-1 until 15 dSm-1 and increased again at 20 dSm-1. At lower salt stress, ABA and proline content declined with increasing the drought stress. However, at higher salt stress, ABA content increased with increasing the drought stress. In conclusion, the salt stress had been found to have a protective role to drought stress for S. imbricata. S. imbricata utilized inorganic ion for osmotic adjustment at lower salinity stress but also accumulate the organic solutes to balance the osmotic pressure of the ions in the vacuole under combined stress conditions. Due to the physical lush green appearance and less maintenance requirements, S. imbricata can be recommended as a native substitute in landscaping under the salt and drought stresses conditions.
