Ridge and furrow planting pattern optimizes canopy structure of summer maize and obtains higher grain yield

Ridge and furrow planting patterns could improve the micro-environment effectively, and ultimately affect maize grain yield. Previous studies mainly focused on planting only on ridges or in furrows aiming to improve the water and temperature conditions, while research on effects of planting in both ridges and furrows on canopy structure and photosynthetic characteristics of individual plants was relatively few. Hence, we hypothesized that planting in both ridges and furrows would (1) optimize maize canopy structure (better light conditions within canopy and delayed leaf senescence), (2) enhance individual leaf photosynthetic characteristics during grain filling, and (3) obtain higher grain yield. To test this hypothesis, we conducted ridge and furrow planting pattern experiments in 2013, 2014 and 2015 growing seasons in Shaanxi, a province in the Northwest of China. Zhengdan958, a corn cultivar planted widely across China, was grown at a density of 67500 plants ha−1. Three planting patterns were arranged as follows: the conventional planting pattern with row spacing of 60 cm (T0 as control), the ridge and furrow planting pattern with one row plants in each ridge and furrow (T1) and the ridge and furrow planting pattern with one row in a ridge and two rows in a furrow (T2). The three-year investigations found that significantly higher relative chlorophyll content and green leaf area per plant were observed in plants of furrows compared to T0 as well as those on ridges, leading to an advantage in terms of individual photosynthetic capacity for plants in furrows, while no significant differences about them in furrows were found between T1 and T2. In addition, we also found that plants in ridge and furrow planting patterns (T1 and T2) exhibited a significantly higher transmission of light to lower layers of the canopy (LT) than that of conventional planting pattern (T0), leading to better light conditions within canopy. Moreover, plants in furrows maintained significantly higher LAI during grain filling, leading to longer LAI duration in T2 planting pattern than other treatments due to more plants in furrows. The highest yield was observed for T2 planting pattern during three experimental years. Relative to control, plants in T2 treatment obtained 27.2%, 18.3% and 31.9% higher grain yield in 2013, 2014 and 2015 growing seasons, respectively. In conclusion, for the tested growing conditions, the planting pattern with one row in a ridge and two rows in a furrow (T2) optimized canopy structure (higher LT and longer duration of LAI), enhanced photosynthetic capacity per plant (higher Pn) during grain filling, and accumulated higher aboveground dry matter at physiological maturity, leading to a greater grain yield.