Analysis on the plant growth and yield formation of double cropping late season hybrid rice in machine transplanting with long seedling age by precision drill sowing

Abstract

<p id="C3">In order to ascertain the beneficial effects of precision drill sowing (PS) in machine transplanting with long seedling age of double cropping late season hybrid rice. In this study, seed of Yongyou 1540 (YY1540) was subjected to precision drill sowing of 16 rows (PS-16, 45.7 g tray^-1), precision drill sowing of 18 rows (PS-18, 60.5 g tray^-1) and traditional broadcast sowing (BS, 60.5 g tray^-1) in standard seedling tray at the same day. Seedling ages of 20, 25, 30, and 35 days were set for machine transplanting to analyze the rice seedling quality, machine transplanting characters, rice population growth, and yield formation between PS-16, PS-18, and BS. The results were as follows: (1) PS improved the light transmittance of seedling population, compared to BS, PS enhanced the seedling quality and increased the percentage of seedlings with tillering buds, among the treatments, PS-16 got the best seedling quality and highest percentage of seedling with tillering buds. (2) Compared to BS, PS significantly reduced the missing hill percent and increased the ratio of hills with 2-3 seedlings transplanted, and there was no significant difference between PS-16 and PS-18. Seedling age prolonging increased the root injury degree and seedling injury rate, and decreased the seedling survival rate after machine-transplanting, in which, PS-16 had the minimal increasing in root injury degree and seedling injury rate, meanwhile PS-16 got the highest survival rate of seedling machine-transplanted. (3) The seedling age prolonging postponed the rice growth duration by increasing the duration of seedling rejuvenation period. Among the seedling age treatments, the shortest period of rejuvenation period was observed in PS-16, and then the growth period minimal delayed in PS-16 with the seedling age prolonging. (4) PS effectively promoted plant tillering, and PS-16 got the best effect. The number of tillers at 10 d after machine transplanting of PS-16 machine was 16.4% and 20.8% higher than that of PS-18 and BS, in average. Seedling age prolonging decreased the tiller number at tillering peak stage, and the tiller number at tillering peak stage was PS-16&gt;PS-18&gt;BS at different seedling age treatments. The productive tiller percentage presented no difference among the sowing methods and seedling ages. (5) Seedling age prolonging decreased the leaf area index and dry matter accumulation by the degree of PS-16&lt;PS-18&lt;BS. (6) PS contributed to yield enhancing by increasing the number of productive tillers, and effectively reduced the yield loss caused by the prolonging of seedling age, and rice yield was PS-16&gt;PS-18&gt;BS under different seedling age treatments, in average. In conclusion, compared to BS, PS could improve the seedling quality, reduce the missing hill percentage in machine transplanting, improve the machine transplanting quality, shorten the seedling rejuvenation period, promote plant tillering, and increase the leaf area index and dry matter accumulation, and then effectively reduce the yield loss of double late season hybrid rice with long seedling age in machine transplanting, and the benefits of PS-16 were better than that of PS-18.