杂交水稻对淹水胁迫的响应及排水指标研究

湖北平原地区夏季强降水频发，稻田易受洪涝灾害。为探明淹水胁迫对杂交中稻生长发育的影响，并在此基础上提出相应的排涝指标，在杂交中稻（丰两优香1号）分蘖期、孕穗期分别设计了淹水深度和淹水时间交互试验。结果表明：淹水处理后，水稻株高、第3、4节间均表现出伸长生长，且与淹水深度和持续时间的累积值（SD）呈显著线性正相关关系，但收获时遭受淹水的各处理其株高均矮于对照，且淹水程度越重，收获时株高越矮。淹水造成水稻减产，且淹水时间越长，淹水深度越深，减产越严重，若以产量受害指标为评价标准，孕穗期对淹水胁迫较分蘖期更敏感。就产量构成要素来看，分蘖期淹水胁迫导致水稻减产主要是有效穗下降、其次是结实率降低；孕穗期主要是结实率、千粒重下降，其次是有效穗减少。以相对产量（Ry）为参数建立的回归方程极显著地展示了Ry与SD、Ry与淹水深度和淹水时间之间的关系，可以作为水稻分蘖期、孕穗期的排涝方程。就淹水要素来说，分蘖期淹水深度对产量的影响比淹水时间大，而孕穗期淹水深度、淹水时间对产量的影响相当。若以水稻减产20%~30%作为排涝标准，分蘖期、孕穗期相应的SD值为1106~1944 cm/d（淹水深度≥18 cm）、265~805 cm/d（淹水深度≥25 cm），并就具体的淹水深度提出了确切的排涝天数

RESPONSE OF HYBRID RICE TO FLOODING AND ESTABLISHMENT OF DRAINAGE INDEX

In Hubei plain area, there is intensive rainfall in summer. During this season, rice field is liable to suffer from flooding disaster. In order to find out the influence of flooding on growth of hybrid rice and put forward relative drainage index, flooding depth and flooding duration representing different flooding stresses were individually simulated in the booting and tillering stages of hybrid rice. The results show that after flooding treatment, rice height, the 3th and 4th internode length all presented elongation. Significant linear positive relationships of these three indexes were also found with the accumulated value of flooding depth and duration time (SD). However, the rice height was found to be shorter than the control when harvested, and the heavier the flooding degree was, the shorter the rice height was at harvest. Flooding was the cause of rice yield loss, longer flood duration and deeper flood depth caused more serious rice yield loss. Using the yield as an appraisal index, flooding stress in booting stage was more sensitive than in tillering stage. As far as yield component is concerned, flooding stress in tillering stage lead to yield loss mainly in the following aspects. Firstly, the decline in effective ears followed by the decrease in seeds setting percentage; while in the booting stage 1000 grain weight and seed setting rate decreased followed by the decline in effective ears. The regression equation for the parameters of elative yield (Ry) dramatically showed the relationship between Ry and SD, Ry and the flooding depth, flooding duration, which can be used as rice drainage equation in tillering and booting stage. As for the flooding components, flooding depth had a greater influence on the yield than flooding duration in tillering stage; while in booting stage flooding depth and duraiton had the same effect on yield.If the rice yield decreased by 20%-30% as the drainage flooding standard, the corresponding values of SD was 1106-1944 cm/d in tillering stage(flooding depth≥18 cm) and 265-805 cm/d in booting stage(flooding depth≥25 cm). The exact drainage days about the concrete flooding depth was put forward as well