Impact of tillage and soil moisture conservation measures on photosynthetic characteristics and water use of winter wheat

Tillage and soil moisture conservation measures have been critical in crop growth, water use and yield output. These measures have improved soil structure and increased soil organic matter content, soil infiltration, and soil temperature. Moreover, tillage and soil moisture conservation measures have increased photosynthetic characteristics. However, the degree of influence of photosynthetic physiological characteristics on crop yield and water productivity efficiency at different growth stages of winter wheat under different tillage and soil moisture conservation measures has been seldom reported. To therefore ascertain the photosynthetic/ physiological characteristics and mechanisms of yield increase under different tillage and soil moisture conservation measures, a field experiment was conducted to determine photosynthesis, yield and water use efficiency of winter wheat at different growth stages under the treatments of deep tillage, no-tillage, straw mulching, organic fertilization and water-retaining agent application. The results suggested that photosynthetic rate and leaf water use efficiency of winter wheat were highest at booting stage and lowest at grain-filling stage. Transpiration rate and stomatal conductance were highest at flowering stage. At all growth stages, photosynthetic rate and leaf water use efficiency were highest under deep tillage treatment, followed by straw mulch treatment. At jointing, booting and flowering stages, transpiration rate was highest under organic fertilization treatment. Then at grain filling stage, transpiration rate was higher under straw mulching and no-tillage treatments than in the other treatments. Transpiration rate under control treatment was lower during all the growth stages of winter wheat compared with that under tillage and soil moisture conservation measures. The trend of change in stomatal conductance and transpiration rate was consistent. Ear length, grain number per panicle, 1000-grain weight, yield and water productivity efficiency of winter wheat increased and total water consumption reduced under different tillage and soil moisture conservation measures. This was especially obvious under deep tillage. Wheat yield and water productivity efficiency were highest under deep tillage, respectively increasing by 19.6% and 38.3% compared with the control. Correlation analysis showed that photosynthetic rate and leaf water use efficiency were positively correlated with yield and water productivity efficiency. The correlations strengthened with advancing growth process, especially so at the flowering stage. At this stage, the effect of photosynthetic rate on wheat yield and water productivity efficiency was more significant than that of leaf water use efficiency.