耕作方式对东北雨养区玉米光合与叶绿素荧光特性的影响

在东北地区设置大田试验，研究不同耕作方式下玉米全生育期耕层土壤温度、土壤含水量、叶片光合性能及叶绿素荧光参数的变化特征.结果表明： 耕作方式对土壤水热性能的影响主要体现在播种-拔节阶段，2010-2011年平地播种中耕起垄(PL)和全生育期平作(PP)处理0～40 cm土层土壤体积含水量在出苗期、苗期和拔节期比传统垄作(LL)处理平均提高5.6%和5.2%、4.6%和7.3%及3.9%和4.8%，苗期5 cm土壤最低温度分别比LL处理高1.4和1.3 ℃.由于土壤水热条件的改善，拔节期PL和PP处理的叶片净光合速率(P_n)、蒸腾速率(T_r)等指标显著高于LL处理，而PSII潜在活性(F_v/F_o)和PSII最大光化学效率(F_v/F_m)无显著差异，表明气孔导度和气孔限制值等气孔因素是导致光合作用差异的主要原因；灌浆期叶片P_n和T_r则以LL和PL处理显著高于PP处理，这主要是由于PP处理在强降雨时期经历了涝渍灾害，光合作用受到抑制.可见PL处理通过改善土壤水热条件增强了玉米光合性能，进而提高了籽粒产量.

Effects of tillage patterns on photosynthetic and chlorophyll fluorescence characteristics of maize in rainfed area of Northeast China.

In 2010-2011, a field experiment was conducted in Northeast China to evaluate the effects of different tillage patterns on the temperature and moisture in topsoil layer and the leaf photosynthesis and chlorophyll fluorescence of maize. The effects of tillage patterns on the soil temperature and moisture mainly manifested at sowing jointing stage. In treatments flat planting with ridging at early jointing stage (PL) and flat planting without ridging (PP), the soil moisture content at the depth of 0-40 cm was significantly higher than that in treatment ridge planting (LL), with the increment being 5.6% and 5.2%, 4.6% and 7.3%, and 3.9% and 4.8% at emergency, seedling, and jointing stages, respectively. The minimum temperature at the soil depth 5 cm at seedling stage in PL and PP was 1.4 and 1.3 ℃ higher than that in LL, respectively. Due to the improvement of soil water and thermal conditions, the leaf photosynthetic rate (Pn) and transpiration rate (Tr) at jointing stage in PL and PP were significantly higher than those in LL, whereas the PSⅡ potential activity (Fv/Fo) and PSⅡ maximal photochemical efficiency (Fv/Fm) had no significant differences among the treatments, indicating that the stomatal factors such as stomata conductivity and stomata limitation were the main factors inducing the photosynthesis differences among the treatments. Furthermore, the PnandTr at grain filling stage in LL and PL were higher than those in PP, mainly due to the high water logging risk in PP in strong rainfall season. Consequently, treatment PL could promote maize photosynthesis through improving soil water and thermal conditions, and further, increase maize grain yield.