Characteristics of Growth and Development of Winter Wheat Under Zero Tillage in North China Plain

To evaluate the growth and development of winter wheat under zero-tillage treatment in the North China Plain, an experiment using a winter wheat (Triticum aestivum L.) cultivar Kenong 9204, with 3 tillage treatments, including conventional tillage with stubble incorporation (CT), rotary tillage with residue returning (RT), and zero tillage with stubble direct drilling (ZT), was conducted in the Luancheng Ecological Experimental Station of the Chinese Academy of Sciences during the 2004-2006 growing seasons. For keeping a similar rate of seedling emergence in all treatments, the seeding rate was increased from 165.0 kg ha^-1 (in CT and RT treatments) to 262.5 kg ha^-1 in ZT treatment. In addition to the characteristics of growth and development of wheat, the plough layer temperature and soil water content were also measured. The basic seedling and tillers in the 3 treatments ranked significantly as ZT < RT < CT (P ≤ 0.05), but the percentage of seed-setting tillers in the ZT treatment was higher than that in the CT treatment. The number of basic seedlings in ZT was lower than that in CT by 28.9% and 11.7% in the 2004-2005 and 2005-2006 growing seasons, and lower than that in RT by 11.7% and 10.0%, respectively. The plant height, leaf area index, dry weight of wheat shoot, and grain yield were the lowest in the ZT treatment because of deficient population. In the ZT treatment, the maximum leaf area indices were 2.9 and 6.0, respectively, in both growing seasons. The grain yield of ZT reduced by 30.1% and 27.2% compared with that of CT and decreased by 15.3% and 25.2% when compared with that of RT, in the 2 growing seasons, respectively. In the ZT treatment, the water content in 0-30 cm soil layer was significantly higher (P < 0.05) than that in the CT treatment during the whole growing period. The topsoil temperature was the lowest in the ZT treatment from seedling to revival stages, indicating that ZT had a "lower temperature effect", which delayed the emergence and revival of seedlings and reduced the tillering rate in the winter wheat. The time of seedling emergence and revival in ZT was 1-3 and 4-5 d later than that in CT and RT, respectively.