Morphological parameters characteristics of mechanically transplanted plant in suitable transplanting period for different rape varieties

Abstract: The effects of rape seedling mechanical transplanting depend on the coupling degree between structure and motion parameters of the planting unit and characteristics of plant morphological parameters. Until now, some researches about the integration of agricultural and agronomic of rapeseed trans planter were carried out, and the links between structural and operating parameters of rapeseed trans planter and rapeseed planting agronomic requirements were established. Though some physical characteristics of rape seedling were measured and analyzed, there were lacks of the studies on characteristics of rape seedling morphological parameters. The morphological parameters of rape seedling are unique, which are affected by the biological characteristics that include the variety, seedling age and individual circumstances. Based on the current reality that the level of mechanical transplanting for rape seedling is low and there is a scarce link between characteristics of plant morphological parameters and the traditional design of trans planter, the research on characteristics of plant morphological parameters about 8 hybrid rape varieties for mechanical transplanting was carried out with the LA-S image processing system in this paper. The characteristics of rape seedling morphological parameters were measured during 28 to 40 days after sowing, which include seedling height, seedling width, seedling cone angle, root length and root diameter. The distribution and growth difference of rape seedling morphological parameters were analyzed. And the reasonable structure and operating parameters of rapeseed trans planter were pointed out, as follow, the appropriate length of the duckbill type planting unit is within the range of 170 mm to 270 mm, the appropriate cone angle of the planting unit is within the range of 35o to 45o, the minimum height of the planting locus is 260 mm, the maximum opening width of the planting unit is 140mm, and the planting depth is adjustable within the range of 60mm to 100mm. The result showed that there were significant differences between some rape varieties in seedling height, seedling width, seedling cone angle and root length. The characteristics of plant morphological parameters during 28 to 40 days after sowing were subjected to normal or skewed distribution, of which the skewness were between -0.48 and 1.61, the kurtosis were between 2.00 and 7.63, the coefficient of variation were between 11.42% and 34.72%. The growth models of the rape seedling morphological parameters during 28 to 40 days after sowing were established, which indicated that there were positive linear relationship between the characteristics of plant morphological parameters including seedling height, seedling width, root length and root diameter and time, the average correlation coefficient was 0.9736, there were negative linear relationship between seedling cone angle and time, the average correlation coefficient was 0.9818. The study showed that it was better to choose the appropriate rape varieties which were suitable for mechanized transplanting and adjust the transplanting time according to the plant developmental morphology, to achieve the integration of agricultural and agronomic for rape mechanical transplanting. In conclude, the research on characteristics of rape seedling morphological parameters provide useful guidance for the design and optimization of rapeseed trans planter.