不同水氮条件对东北寒地黑土直播稻光响应特征的影响

Effects of Different Water and Nitrogen Conditions on Characteristics of Light Response Curve of Direct-seeding Rice in Cold and Black Soil Region of Northeast China

为了揭示寒地黑土直播稻在不同灌水方式和施氮水平下功能叶片光响应特征,以测坑试验水直播水稻为研究对象,采用全面试验方法,设灌水方式和施氮量2个因素,针对水稻分蘖期和抽穗开花期开展了不同水肥条件下直播水稻叶片光响应特征的研究。结果表明:随氮肥施用量的增加,直播稻功能叶片的光响应曲线上升,光强高于600μmol/(m^2·s)时,不同施氮量处理的光响应曲线间距变大。运用非直角双曲线模型建立水稻叶片光合光响应曲线的拟合,得出不同水氮处理下直播水稻叶片的光响应特征参数,结果显示,随着施氮量的增加,最大净光合速率Pnmax、表观量子效率α和光饱和点LSP上升,光补偿点LCP下降;而同施氮量条件下,控制灌溉处理的Pnmax、α和LSP高于淹灌处理,LCP低于淹灌处理。因此,在0~135kg/hm^2的范围内增加施氮量和控制灌溉有助于提升直播稻功能叶片光合作用能力,提高其对光能的利用率和对强光及弱光的适应能力,有效改善叶片光响应特征,提高水稻产量,所以在进行直播水稻栽培研究时,要充分考虑不同水肥条件对其光响应特征的影响。

In order to reveal the influence of irrigation methods and nitrogen fertilizer on characteristics of functional leaf＇s photosynthetic light response of direct-seeding rice in cold and black soil region,the test-pit experiments was carried out Two factors were set,including irrigation methods and nitrogen fertilizers.The characteristics of photosynthetic light curve of rice leaf with different water and nitrogen regulations in the tillering stage and the heading-and-flowering stage was studied by using comprehensive test design.The result showed that when nitrogen rate increased,photosynthetic light response curves of direct-seeding leaf rised,especially when the photosynthetic photon flux density was higher than 600μmol/（m～2·s）.Parameters derived from non-rectangular hyperbola model indicated Pnmax（maximum photosynthesis rate）,α（apparent quantum yield）and LSP（light saturation points）increased with the increase of the nitrogen rate,while LCP（light compensation points）reduced.Pnmax,αand LSP of controlled irrigation treatments were higher than those of flood irrigation treatments at the same nitrogen rate,while LCP was lower.In conclusion,higher nitrogen inputs,within the range of 0～135 kg/hm^2,and controlled irrigation method lead to the increase of photosynthetic capacity,enhancing the light use efficiency and the adaptability to both strong and weak light of rice leaf.These findings were helpful for improvement of photosynthetic light response curve and rice yield.It should be taken into full consideration for the effects different nitrogen levels and irrigation ways on leaf＇s photosynthetic light response curve in paddy of direct-seeding rice.