Effects of Two Mechanical Planting Methods on the Yield and Quality of High-Quality Late Indica Rice

The experiment was conducted to clarify the differences in the yield and quality of double cropping high-quality late indica rice and the selection criteria for variety tapes under mechanical transplanting (MT) and mechanical direct seeding (MS).

Early-maturing late indica rice, medium-maturing late indica rice, moderately late-maturing late indica rice, late-maturing late indica rice and extremely late-maturing late indica rice were used as materials, and two planting methods including MT and MS were set to study the yield and quality characteristics of high-quality late indica rice.

(1) The seed setting rate and the number of spikelets in the population of the high-quality late indica rice under MT were significantly higher than that under MS, and the 1000-grain weight under MT also increased, finally the actual yield was significantly increased. For MT, the medium-maturing late indica rice had the highest yield, followed by moderately late-maturing late indica rice; while for MS, the early-maturing late indica rice had the highest yield, followed by medium-maturing late indica rice. (2) Compared with MS, the processing quality of high-quality late indica rice varieties under MT was better for the significantly higher brown rice rate, milled rice rate and head rice rate, but the appearance quality deteriorated because of the increased chalky rice rate and chalkiness degree. The cooking quality improved for higher gel consistency, breakdown, taste value and lower amylose content. The highest brown rice rate, milled rice rate, and head rice rate were all found in medium-maturing late indica rice under two planting methods, chalky rice rate and chalkiness degree among different varieties showed the trend of extremely late-maturing late indica rice<late-maturing late indica rice<moderately late-maturing late indica rice<medium-maturing late indica rice<early-maturing late indica rice. For mechanical transplanting high-quality late indica rice, the best cooking and taste and nutritional quality appeared in moderately late-maturing late indica rice, followed by medium-maturing late indica rice. For mechanical direct seeding high-quality late indica rice, medium-maturing late indica rice had the best cooking and taste and nutritional quality, early-maturing late indica rice also had high taste. (3) The milled rice rate and head rice rate were significantly positively correlated with daily mean temperature in 20 days after full heading, and the chalkiness rate and chalkiness degree were significantly positively correlated with daily mean temperature and daily mean maximum temperature. Taste value was observed to be significantly positively correlated with daily mean temperature and daily mean maximum temperature in 20 days after full heading.

Therefore, based on the comprehensive consideration of high yield and good quality, medium-maturing late indica rice and moderately late-maturing late indica rice were the most suitable for the mechanical planting method, while the moderately late-maturing late indica rice could also be considered for more attention to good tasting. The early-maturing late indica rice were the most suitable for mechanical direct seeding method, and medium-maturing late indica rice could be considered to use for obtaining high quality.