旱涝急速转换条件下双季超级杂交水稻产量形成机理

"Drought-flood abrupt alternation" means that an especially drought length comes on top of an extra flood span in the same season, while the extreme occurrence of drought and flood occurs by turn in short time. Generally, it is a high frequency meteorological disaster during summer in south China area and the Yangtze River valley. People pay highly attention to it as a result of serious "drought-flood abrupt alternation" occurred in double-season rice area of the Yangtze River valley in 2011 especially, and it caused enormous losses. There were lots of researches on drought injury or flood damage in rice, however, the research on "drought-flood abrupt alternation" was inadequate thorough and system. Up to date, the conclusions of the small quantity of research on "drought-flood abrupt alternation" in rice also were greatly diverse due to the dissimilarity of the tested materials, the occurred period, intensity and duration of the drought and flood. There are few reports of the research on "drought-flood abrupt alternation" using the super hybrid varieties for the double-season rice as the tested materials. The large acreage spread super hybrid rice varieties in the double-season rice area of Jiangxi province will be selected, artificial simulation disposes of different intensity combinations of "drought-flood abrupt alternation" during the periods for the meteorological disaster occurred frequently will be put up, also the yield, photosynthesis, biomass, root activity, osmoregulation, protected enzyme activity, carbon isotopic compositions δ13C and hormones will be inspected, and the aim of the research is to ascertain the induced disaster character and threshold value by "drought-flood abrupt alternation", also prove up the physiological mechanism of the yield formation for the double-season super hybrid rice variety under the condition of "drought-flood abrupt alternation" to supply theoretical basis of the anti-disaster and disaster mitigation.

"旱涝急转"指同一季节内一段时间特别旱，紧接着一段时间特别涝，即旱涝极端事件在短时间内依次发生的气候现象。通常是华南地区、长江流域夏季频发的一种气象灾害，特别是2011年长江流域双季稻区遭受严重的"旱涝急转"事件，造成重大损失引起人们极大关注。虽然以往对水稻"旱害"、"涝害"研究较多，但对"旱涝急转"研究不够系统深入，迄今与其有关的少量报道也由于试验用材料，旱涝发生时期、强度及持续时间的不同，所得结论差异较大，鲜见有以双季超级杂交稻品种为试验材料的研究报道。本项目拟选用江西等双季稻区大面积推广的超级稻品种，在常发生该气象灾害时段设置不同"旱涝急转"强度组合进行人工摸拟处理，考查产量、光合、生物量、根系活力、渗透调节物质、保护酶活性、碳同位素δ13C、内源激素等，判明"旱涝急转"致灾性并划分致灾阈值，探明双季超级杂交稻"旱涝急转"条件下产量形成的生理机制，为该气象灾害的抗灾减灾提供理论依据。

“旱涝急转”指旱涝极端事件在短时间内依次发生的气候现象，是华南地区、长江流域夏季频发的一种气象灾害，常给生产造成重大损失，迄今对其致灾性及机理等问题研究不够系统深入。选用双季超级稻品种，在常发生该气象灾害时段设置不同“旱”、“涝”及“旱涝急转”强度组合进行人工摸拟处理，考查产量、光合、生物量、渗透调节物质、保护酶活性、δ13C、内源激素等，初步探明：“旱”、“涝”及“旱涝急转”使双季超级杂交稻单株产量均不同程度下降，早稻轻旱不涝、重旱不涝、不旱轻涝、不旱重涝、重旱轻涝急转、重旱重涝急转、轻旱轻涝急转、轻旱重涝急转单株产量分别比不旱不涝降低8.89%、21.42%、8.33%、12.04%、19.65%、31.23%、15.39%和17.29%，晚稻降低6.21%、15.06%、7.77%、11.53%、17.40%、20.85%、13.46%和11.70%；早、晚稻“旱涝急转”产量下降的主要原因是较大幅度降低了单株有效穗数、每穗总粒数、结实率和二次枝梗数；一定范围内“旱涝急转”对双季超级杂交稻产量形成具有一定的拮抗作用，超过一定程度则表现为叠加损伤作用，其中早稻以干旱保持6d，全部浸没淹涝4d为其阈值，晚稻以干旱保持4d，全部浸没淹涝3d为其阈值；干物质积累量上，早、晚稻均是以“旱涝急转”最低；“旱涝急转”较大幅度降低了叶片叶绿素含量，显著降低了稻叶光合速率，蒸腾速率、气孔导度和胞间CO2浓度也不同程度下降；“旱涝急转”交替胁迫后初期，稻叶渗透调节物质游离脯氨酸、可溶性糖、可溶性蛋白、MDA含量等以及保护酶POD、SOD和CAT等活性均不同程度上升，胁迫解除后均缓慢恢复至正常水平；“旱涝急转”处理下稻叶内源生长促进类激素IAA 和GA3含量上升，内源生长抑制类激素ABA 含量较高；“旱涝急转”处理下稻叶δ13C值δ15N值波动性大。“旱涝急转”将严重影响双季杂交稻产量形成，与处理结束后一段时间内叶绿素降解加速、光合速率显著下降、叶片渗透调节物质含量上升、保护酶活性增强、内源生长促进类与抑制类激素比例失衡及叶片δ13C和δ15N值波动较剧烈有关。研究可为该气象灾害的抗灾减灾提供理论依据。