[Effects of long term tillage practices on photosynthetic characteristics and grain yield of wheat]

A field experiment was conducted to study the effects of long-term tillage practices on photosynthetic characteristics of flag leaf, dry matter accumulation and its allocation, and grain yield, with a wheat cultivar, Jimai 22, in both 2013-2014 and 2014-2015 growing seasons. Four tillage practices, namely rotary tillage (R), plowing (P), strip rotary tillage and subsoiling at an interval of 2 years (SRS), and rotary tillage and subsoiling at an interval of 2 years (RS), were conducted in field for 9 years since 2007. The results showed that the net photosynthetic rate (P_n), transpiration rate (T_r), and stomatal conductance (g_s) of flag leaves under SRS treatment were significantly higher than those of other treatments from 21 to 35 days after anthesis. The SRS treatment had higher average photosynthetically active radiation (PAR) capture ratio than RS and P treatments, while the lowest values were found under R treatment during grain-filling stage. Compared with the other treatments, the plants of SRS treatment had the highest accumulation of dry matter at maturity, the highest allocation of dry matter in grains, and the highest contribution ratio of dry matter from vegetative organs to grains after anthesis. The grain yield and water use efficiency of SRS treatment were significantly higher than those of the other treatments, and the water consumption amount of SRS treatment was significantly higher than that of both R and P treatments, with no significant difference from the RS treatment. Under the current experimental condition, it was suggested that SRS would be the most effective tillage practice to increase both grain yield and water use efficiency for winter wheat production.