深松对夏玉米物质生产、光合性能及根系生长的影响

Effects of Subsoiling on Dry Matter Production, Photosynthetic Performance and Root Development of Summer Maize

以郑单958为试验材料，设播前深松、4叶期深松处理，以黄淮海地区普遍采用的免耕直播作为对照，分析玉米全生育时期内叶面积指数、净光合速率、叶面积持续期、干物质积累、相对生长率、根系性状以及产量及其构成因素的变化。结果表明，两种深松方式对比，物质生产、光合性能及根系生长方面均差异显著。与免耕直播相比，播前深松可以显著提高玉米拔节期叶面积指数，有效提高吐丝期净光合速率，显著增加拔节期干物重、吐丝期0～100cm根系总干重以及20～30cm土层内根系的活力；叶面积持续期、净同化率与相对生长率变化幅度不大。4叶期深松则导致植株的各方面表现较差，营养生长受到限制，叶源不足，叶片早衰。与对照（免耕直播）比较，播前深松增产1．7％，4叶期深松减产11．5％，两种深松方式间差异显著。夏玉米区播前深松具有提升玉米产量的优势，4叶期深松则限制了玉米生长和产量提升。

A field experiment was conducted to compare three tillage methods including subsoiling before sowing ）, subsoiling at fourth leaf stage（ Ⅱ ）, non-tillage（CK） in 2012. The effects of subsoiling on leaf area index,net pho- tosynthetic rate, leaf area duration, dry matter accumulation, relative growth rate,root traits, yield and yield component were studied.The results showed that there are significant difference between the two subsoiling methods on dry matter production, photosynthetic performance and root development in summer maize. Leaf area index was improved by subsoiling before sowing as compared to CK at elongation stage. In addition, net photosynthetic rate at silking stage, dry matter weight at elongation stage, total root dry weight 0-100 cm soil depth and root vigour at 20-30 cm soil depth at silking stage were all significantly improved. While leaf area duration, net assimilation rate and relative growth rate showed less response. On the contrary, the plants under subsoiling at fourth leaf stage performed worse for all charac- ters, which related to the restriction of vegetative growth, insufficient leaf source and leaf senescence. Generally, grain yield-under subsoiling before sowing increased by 1.7% as compared to CK, while reduced by 11.5% under subsoil- ing at fourth leaf stage, and two subsoiling methods showed significant difference. In conclusion, subsoiling before sowing（ I ） had advantages of increasing summer maize yield, however, subsoiling at fourth leaf stage（ Ⅱ ） imposed re- strictions on maize development and yield.