灌水方式和灌溉量对冬小麦根冠结构的影响

Effects of Different Irrigation Methods and Amount on Root and Canopy Structure of Winter Wheat

为了解不同灌水方式和灌溉量下冬小麦根冠结构的变化,在2年试验的基础上,设置畦灌和喷灌两种灌水方式,畦灌设置1 300和1 911 m3·hm-2两种灌水量;喷灌设置900、1 200、1 500、1 800m3·hm-2四种灌水量,与灌水时期形成6个组合处理,分析了灌水方式和灌水量对冬小麦叶面积、光合性能、根系生长、产量及水分利用效率(WUE)的影响。结果表明,喷灌下少量多次灌溉能促进叶面积指数(LAI)提高,尤其早春灌返青水或起身水可明显增加单叶面积,促进倒5和倒6叶生长,灌水1 200m3·hm-2就可以获得较高的单叶面积和LAI;喷灌条件下LAI和光能截获率明显高于畦灌。少量多次喷灌可明显提高叶片净光合速率(Pn),并延缓其在生育后期的下降,促进生育中后期干物质积累;与畦灌比较,喷灌主要是提高了花后叶片Pn。喷灌处理的1m土层内根干重、根长密度和根表面积明显小于畦灌处理,但根系变粗,0~20cm根长度减小。在灌水次数较少、灌溉量较低的条件下,喷灌处理增产增效显著,而在灌水次数较多、灌溉量较高的条件下,喷灌处理由于LAI过高,奢侈蒸腾增加,反而不利于产量和WUE提高。相比畦灌,少量多次喷灌使小麦形成了一个典型的'大冠层、壮根系'的形态特征,在2012/2013年气候条件下,喷灌1 200m3·hm-2、灌水3~4次、拔节期灌溉第一水就可以构建高产高效冠层。

In order to investigate the root and canopy structure of winter wheat under different irrigation methods and rates,the change trends of leaf area,photosynthetic performance,root growth,grain yield and WUE were analyzed based on 2year experiment of winter wheat.The experiment was employed with two irrigation methods,border irrigation with two irrigation amounts(1 300 and 1 911m3·hm-2),and spraying irrigation with six irrigation combinations of amounts and stages(900,1 200,1 200,1 200,1 500 and 1 800m3·hm-2,respectively).The main results showed that leaf area index(LAI)was higher for spraying irrigation treatments owing to more irrigation times,especially irrigation at reviving and erecting stage could obviously promote the leaf area growing,especially for the 5and 6leaf from top compared with border irrigation.The high LAI was obtained under irrigation amount of 1 200m3·hm-2,but the canopy structure was too larger and light transmission de-creased with further increase of irrigation quantity,indicating that canopy structure was unsuitable under high irrigation quantity.LAI and light interception rate of spaying irrigation was significantly higher than that of border irrigation.For spraying irrigation,leaf Pn was higher and the decreasing rate of Pn was lower owing to more irrigation times,so leaded to high dry matter accumulation in the late growth stage.Leaf Pnafter anthesis of spaying irrigation was significantly higher than that of border irrigation.Compared with border irrigation,root dry weight,density of root length and surface area of root were significantly smaller for spraying irrigation in 100 cm soil depth,but root diameter was larger,and length of root in 0~20cm soil depth was smaller.Grain yield and WUE for spaying irrigation treatments were higher than that for border irrigation under less irrigation amount,while higher LAI and luxury transpiration decreased significantly grain yield and WUE for spaying irrigation treatments under the condition of more irrigation times and more irrigation amount.'Big canopy,strong root system'was formed under irrigation amount of 1 200m3·hm-2 with 3~4time irrigation and first water irrigation at jionting period for spaying irrigation,in this condition a high grain yield and WUE could be achieved simultaneously.