Abstract:
The uniform population in the machine-transplanted rice can be expected to effectively improve the grain yield. This study aims to clarify the impact of the interaction between the precise drill sowing and tray overlapping emergence on the uniformity of population and yield composition in machine-transplanted rice. The homogeneous population was also achieved for the high yield. The Indica-japonica hybrid rice ‘Yongyou 1540’ was taken as the test cultivar. The field test was taken as the two sowing rates (T1: 36.6 g, T2: 73.2 g), the precision drill sowing (PS) and traditional broadcast sowing (BS), as well as the tray overlapping (OL) and tray nonoverlapping (NL). The standard 9-inch stackable trays were used to grow seedlings. The machine-inserted samplings were realized into the 18 transverse and 40 longitudinal seedlings. A comparison was also made on the seedling quality, tiller dynamics, leaf area index, dry matter accumulation, yield, and its components under different treatments. The results showed that: (1) The tray overlapping significantly promoted the seedling quality (
P<0.05). The average seedling evenness of the PS was 19.29 percentage points higher than that of BS. The average seedling evenness of OL was 36.61 percentage points higher than that of the NL. (2) PS significantly increased the uniformity of population, compared with the BS. The OL significantly enhanced the uniformity of the population, compared with the NL treatment (
P<0.05). The PS with the OL increased the uniformity of population by 44.21 and 60.31 percentage points at the transplanting and the heading stages, respectively. High-uniformity population shared the highest peak seedling numbers, thereby obtaining more productive panicle numbers. (3) Both precision drilling and OL increased the leaf area index and the dry matter accumulation of the population. (4) The PS with the OL was achieved in the high yield for the greater number of productive panicles in the population. The seeding rate enhanced the yield under the traditional BS and NL treatment. (5) Partial least squares path model analysis (PLS-PM) verified that the direct effect of the OL on the rice population uniformity was 0.720 9, which was greater than 0.307 5 of the precise strip sowing. There was the largest direct effect of the rice population uniformity on the productive panicle numbers and the dry matter weight for the aboveground. The direct effects of the productive panicle numbers and the dry matter weight for the aboveground on the yield reached 0.986 4 and 0.825 0, respectively. Therefore, the PS and OL significantly improved the seedling's evenness and the uniformity of the machine-transplanted rice population (
P<0.05). The high yield was obtained to increase the productive panicle numbers and dry matter accumulation of the population. The seed distribution and development were also dependent mainly on the technical reasons in the practical production. The seeding rate improved the uniformity of the machine-transplanted rice population, in order to alleviate the yield losses.