Experimental Study On Effects Of Climate Change On Rice Growth In South Region

The objective of this study is to illustrate the effects of climate change on rice growth in southernChina. This study contained two field experiments, sowing date experiment in the south of Jiangsu andOTC experiment in the south of Hubei. Sowing date experiment set six sowing dates every seven daysafter local normal sowing date to get temperature change during rice growth stage. In OTC experiment,OTC equipments were used to control the temperature and CO2concentration. There were fivetreatments based on field environment to observing the effects of climate change on rice growth,including field, OTC without any management, raising2oC, increasing CO2concentration60ppm, andraising2oC with CO2concentration increasing60ppm. In this design, the treatments of field and OTCwith no management were set to eliminate the system error caused by the OTC equipments. The resultsof this study were as follows:1The results showed that warming contributed positive impacts to rice growth in southern Jiangsu.Temperature rising shortened the length of growth stages, especially in vegetative growth period. LAIincrement increased with the temperature rising in sowing to jointing and jointing to heading stages, butdecreased in heading to mature stage. Temperature rising accelerated the rate of leaf growing during theearly rice growth period, and leaf senescence in later stage. The influence of temperature rising on LADof rice showed decreasing tendency in sowing to jointing and jointing to heading stages, but increasingtendency in heading to mature stage. DMA increment and CGR increased with temperature rising in allgrowth stages. The beneficial effects of rising temperature on the rice growth were limited by theoptimum temperature. In this study, the temperature saturation points (optimum temperature) of threerice types affected by temperature rise all appeared at heading and maturity stage. The optimumtemperatures of medium-maturing medium japonica were28oC and23oC in heading and maturity stagerespectively, which were27oC and22oC of late-maturing medium japonica and26.5oC and21.5oC ofearly-maturing late japonica. Three rice varieties showed a same changing trend affected by temperaturerising, but the sensitivity of different growth stages and varieties ranged. Considering the climatechange in south of Jiangsu under warming scenarios, the planting area of medium-maturing mediumjaponica might get further expansion, because of the higher temperature saturation points than the twoother varieties. To make better use of heat resource after temperature rise, rice varieties of highsensitivity should be recommended under the condition of temperature rise beneficial.2The temperature condition in Jingzhou region was not suitable for early-season rice growth,especially at later growth stage. The temperature was too high and already beyond the upper limit ofearly-season optimum temperature. The risk of heat injury would increase after2oC rising, as a resultthe early-reason rice yield of this region would decrease. Temperature rising would do harm toearly-reason rice growth, so that under warming scenarios, early-season rice could not adapt with theclimate change and the production would be affected. The effects of CO2concentration elevating on ricegrowth mainly reflected as CO2fertilization, which would do good to rice yield formation. CO2 concentration elevating could promote the synthesis of photosynthetic material. Instead of adding thephotosynthetic effective area, CO2concentration elevating improved the efficiency of photosynthesis,and was benefit to rice grain filling. What`s more, the lower proportion of empty-unfilled grains andhigher1000-grain weight also showed that CO2concentration elevating would help rice with absorbingand fixing carbon.