Abstract: 【Objective】Under the pattern of interplanting rapeseed in late rice, standing stubble height affected soil water storage and preservation, interplanting rapeseed emergence rate, growth and development. This study aimed at finding out a proper standing stubble height to promote emergence rate, growth and development, and finally to improve yield of interplanting rapeseed. These results provide practical references for reaching efficiency and organic combination of agronomy with agricultural machinery.【Method】Fengyou 730, a elite rapeseed cultivar, was employed in a field experiment with four stubble height treatments during the 2014-2016 growing seasons at Jiangxi Institute of Red Soil, Jiangxi province. Four stubble height treatments were compared: 20, 30, 40 and 50 cm. The seedling rate, mature plant rate, agronomic traits at two growth stages (wintering stage and full bloom stage), chlorophyll content of leaves, root activity, yield were measured in this study.【Result】In the range of 20-50 cm, an increased stubble height could thoroughly promote the seedling density, the seedling rate and mature plant rate were increased at the initial stage but deteriorated under a further increased stubble height, the optimal seedling rate and mature plant rate were the treatment with stubble height of 40 cm, the mature density was relatively larger. The seedling rate and mature plant rate of 40 cm stubble height were 13.73%, 7.09% and 13.18%, 7.23% higher than that of 20 cm and 30 cm, respectively, but the differences were not significant between 40 cm and 50 cm. Stubble height significantly affected growth and development of interplanted rapeseed. The number of total leaves, number of green leaves, width of maximum leaf, crown diameter, the dry weight of individual plants and the chlorophyll content of the top 3 leaves, root activity were gradually fell, the length of maximum leaf was gradually increased, the leaf area index and dry matter of population plants were primitively increased and then subsequently fell with increasing of the stubble height. The yield per plant of interplanted rapeseed in rice was diminished, whereas the yield per area was heightened initially and diminished later with increasing of the stubble height, and the optimal rapeseed yield could be approached with stubble height of 40 cm. Compared with the stubble height of 20 cm, the yield increasing rate of the stubble height of 40 cm was 18.92%, the yield increased obviously. Stubble height was highly related to yield components of interplanted rapeseed in rice including primary branches, siliques per plant, siliques on main inflorescence, 1000-grain weight, dry matter weight per plant, and yield per plant with a substantial negative correlation or significant negative correlation.【Conclusion】A lower seedling rate, mature plant rate and mature density, but strong individuals under a lower stubble height as well as a higher mature density and weak individuals under a higher stubble height could result in yield reduction. Results of the study indicated that late rice stubble height of 40 cm was helpful to population growth and strongly improved the yield of interplanted rapeseed.

Key words: late rice, rice stubble height, interplanting rapeseed in rice, growth and development, yield