根际增氧模式的水稻形态、生理及产量响应特征

Response of Morphological, Physiological and Yield Characteristics of Rice (Oryza sativa L.) to Different Oxygen-Increasing Patterns in Rhizosphere

地表积水是导致水稻地下部分(根系)缺氧胁迫的主要原因。根际缺氧时,提高水稻根系通气(增加孔隙度)可能会减少营养物质的吸收面积,因此,根系必需在形态和代谢上进行一定的调节,而这种调节又会影响作物生长和根际状况。控制灌水(增加土壤和空气的接触时间)是目前常见的一种根际增氧途径,而化学物质增氧模式还处于试验阶段。为考察不同增氧模式对水稻根际缺氧调控的田间应用效果,本研究分别于2007年和2008年,采用过氧化尿素(T1)、过氧化钙(T2)以及干湿交替灌溉(T3)的根际增氧模式并以长期淹水田块为对照(CK),监测水稻根系及地上部分形态、生理、光合物质积累及产量形成特征。结果表明,与CK比较,处理T1、T2和T3对国稻1号和秀水09的增产幅度2007年分别为3.1%/11.5%、10.2%/14.9%和18.9%/16.4%;2008年分别为11.56%/6.57%、8.48%/9.20%和13.56%/9.39%。使根际增氧的响应大致表现为根系孔隙度下降、齐穗期根体积增大、根系活力提高;前期分蘖数增加较快,有效穗多;叶片叶绿素含量在齐穗后下降较慢,剑叶SOD和POD含量较高,MDA含量较低;齐穗后叶片光合作用对穗部干物质积累贡献大。不同增氧模式对水稻生长的影响虽然存在一定的差异,但对土壤淹水导致的根际缺氧胁迫,均起到一定的缓解作用。

A major constraint resulting from excess water on the surface of the ground for rice is anoxic stress to root system. Characteristics of roots allowing internal aeration may conflict with those for water or nutrient acquisition, thereby, morphological and physiological adjustments are inevitable, and possibly affect plant growth and the rhizosphere conditions. To date, alternate dry/wet irrigation, which can keep sufficient commutative space of gas between air and soil during rice growth period duration, is the main method to alleviate anoxic stress in rice rhizosphere for field cultivation. Besides, other oxygen-increasing patterns, such as aeration by peroxide application, are still at experimental stage. In order to monitor morphological and physiological responses, as well as yield characteristics of rice to the three oxygen-increasing patterns in rhizosphere, two-year field trials （2007-2008） were performed. Three oxygen-increasing patterns were adopted： application of urea peroxide （T1）, application of calcium peroxide （T2）, and alternate dry/wet irrigation （T3）. Continuous submerging condition （no oxygen increased in rhizosphere） was taken as control （CK）. The results showed that compared with the control （CK）, the yield of Guodao 1 （indica） and Xiushui 09 （japonica） under the treatments of T1, T2, and T3 were increased by 3.1% and 11.5%, 10.2% and 14.9%, and 18.9% and 16.4% in 2007, respectively; and by 11.56% and 6.57%, 8.48% and 9.20%, and 13.56% and 9.39% in 2008, respectively. In addition, the main effects of oxygen-increasing patterns on rice growth were as follows： （1） Porosity of root system was decreased, but the root volume and the activity of root system were increased. （2） Panicle number was increased due to the rapid development of tillers during tillering stage. （3） Chlorophyll content of leaves decreased more slowly after heading stage, but SOD and POD activities were higher, and MDA concentration was lower in leaves at harvest, so dry matter in panicle after heading that derived from leaf photosynthesis was much more than that accumulated in stem and sheath before heading. The three oxygen-increasing patterns had different effects on rice growth, but under hypoxic stress caused by the inadequate supply of oxygen under the submerged soil, oxygen-increasing patterns all could effectively alleviate the stress for root system and above-ground part of plant.