不同育秧方式和插植密度下华南双季晚籼稻根系活力的初步研究

本试验于1995年晚季初步研究了水、旱育秧方式和不同插植密度下根系活力的变化趋势及与地上部生长发育的关系。结果表明:(1)旱育秧苗根系活力明显高于水育秧,根系活力与白根数、地上部苗体干/鲜重比值呈显著正相关,与褐根数、苗高、叶龄和百苗干、鲜物重呈负相关。(2)旱育单苗移植处理的根系活力在水稻整个生育过程中均高于旱育多苗移植处理,水秧单苗和多苗移植处理。生育后期根系活力与主茎功能叶片叶绿素含量和叶面积系数分别呈极显著正相关和正相关,旱育秧苗的这些特性有利于移植后叶片与分蘖的快速形成及生育后期延缓叶片衰老,提高籽粒充实度。同时提出,在水肥管理上应适当加大后期穗肥比例,改善光照条件和土壤的通气排水状况,以便充分发挥旱育稀植秧苗的增产优势。

PRELIMINARY STUDIES ON ROOT ACTIVITY OF RICE WITH DIFFERENT SEEDLING RAISING MEASURES AND PLANTING DENSITIES

The experiment for studying the relationship between root activity and shoot development in rice growth duration under the conditions of dry-nursery and wet-nursery seedling raising and different planting densities was conducted in the late season of 1995. The results indicated that the root activity of seedling raised in dry nursery was significantly higher than that in wet nursery. The significant positive correlation was found in root activity with the number of white roots, and with the ratio of dry/fresh weight; but negative correlation in root activity with rust roots, seedling height, leaf number and 100-seedling fresh weight as well as dry weight. This character in dry-nursery raising seedlings might benefit to the available material base for the early leafing and tillering after transplanting. The root activity in treatment with single seedling transplanting from dry-nursery was higher than that in the other three treatments during the rice growth stage. At the late growth stage, root activity showed a significant positive correlation with leaf chlorophyll content of the main culm, and a positive correlation with leaf area index. Thus, this can prevent the early ageing of rice plant at the late stage, and improve the filling of grain. Meanwhile, it would bring "dry-nursery seedling raising and sparse planting" possessing superiority of increasing grain yield into full play if more fertilizer can be applied at heading stage, and light condition and soil drainage can be improved through fertilizer and water management.