THE STUDIES OF THE PLANT COLD－RESISTER AND ITS APPLICATION IN RECE SEEDLING RAISING

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Effects of soilless substrates on seedling quality and the growth of transplanted super japonica rice

This study was conducted to investigate the effects of soilless substrates of hydroponically grown long-mat seedlings(HLMS) on seedling quality and field growth characteristics of transplanted super japonica rice. A widely grown conventional super japonica rice cultivar(Wuyunjing 23) was selected as the test material. The effect of HLMS on seedling quality, mechanical transplantation quality, field growth characteristics, yield, and benefit-cost ratio were compared with seedlings grown in organic substrates and traditional nutritive soil, which was selected as the control. Root number, root twisting power and root activity of seedlings cultivated by HLMS were decreased compared to that of the organic substrates and control. However, seedling root length as well as aboveground growth were increased compared to the organic substrates and control seedlings. In the HLMS, the content of gibberellin acid(GA_3) decreased while abscisic acid(ABA) content increased compared to that of the organic substrates and control seedlings. During the early stages after transplanting, the re-greening of HLMS was delayed compared to that of the organic substrates and control seedlings. Nevertheless, there were no significant differences in tiller dynamics and crop yield among the HLMS, organic substrates and control treatments. The effects of HLMS on seedling production were similar to those of the organic substrates and traditional nutritive soil in the present study, suggesting that HLMS have the potential to replace traditional nutritive soil in seedling production without decreasing crop yield. Finally, it is important to reduce organic substrates and topsoil dependence during rice seedling production and worthwhile to consider HLMS popularization and its application on a larger scale.

Development Status and Countermeasures of Passiflora spp.Seedling Industry in Qinzhou,Guangxi

In recent years,the development trend of passion fruit seedling industry in Qinzhou,Guangxi is good,but on the whole,it is still in its infancy and the development of the industry is fragile.This paper briefly described the development status and existing problems of the passion fruit seedling industry in Qinzhou,Guangxi,and put forward reasonable suggestions in order to promote the healthy development of the passion fruit seedling industry,increase farmers’income and prosper rural economy.

Effects of Different Planting Densities on the Yield of Rice Developed from Seedlings Dry Raised in Plug Trays

[Objectives]This study was conducted to investigate the effects of different planting densities on rice tillering dynamics and yield. [Methods]The effects of different planting densities on rice yield were studied based on seedlings dry raised in plug trays. [Results]Planting density had obvious effects on tillering dynamics,number of panicles per unit area,number of grains per panicle and rice yield under the condition of seedlings dry raised in plug trays. Comprehensive analysis showed that the row spacing × hill spacing = 25 cm × 14 cm,that is,the planting density of 2. 85 × 10~5 hills/hm^2,achieved the highest yield,at 9 960 kg/hm^2. [Conclusions]This study provides a scientific basis for optimizing rice cultivation techniques and achieving high yield and high efficiency in rice production.

Design and experiment of the soil-covering and soil-compacting device for seedling raising and sowing of trough type panax notoginseng

In order to improve the seedling quality of Panax notoginseng,combined with the special agronomic requirements of Panax notoginseng,a sharp angle roller soil-covering and soil-compacting device integrating the functions of soil-covering and soil-compacting was designed.Based on the theoretical analysis of seed ditch conditions,soil-covering process and soilcompacting process,the structure of soil-covering and soil-compacting device was designed.Through theoretical analysis and calculation,the diameter and length of soil-covering and soil-compacting wheel were 20 cm and 10.7-14.1 cm,respectively,the sharp angle and height range were 45°-105°and 0.8-1.6 cm respectively,and the spring stiffness was 38.54 N/mm;Using the discrete element method to simulate the soil-covering and soil-compacting process,it was obtained that when the sharp angle range was 60°-90°,the sharp angle height range was 0.8-1.2 cm,and the soil-covering effect was better;Taking the forward speed,ballast pressure,sharp angle and sharp angle height of the planter as the test factors,and taking the soil-covering thickness,grain spacing and soil compactness as the indexes,the four factor and three-level Box-Behnken Design test was carried out.The response surface test analysis method was used to establish the regression equation between the factors and indexes,and determine the best parameter combination:the forward speed was 6.5 m/min,the ballast pressure was 360.5 N,the sharp angle was 67°,and the sharp angle height was 1 cm,at this time,the soil-covering thickness was 0.64 cm,the grain spacing was 5.03 cm,and the soil compactness was 321.77 kPa.According to the soil trough test,the design of soil-covering and soil-compacting device met the agronomic requirements of plant spacing,soil-compactness and soil-covering thickness during seedling sowing of Panax notoginseng.The research results can provide a reference for the design of Panax notoginseng seedling planter integrating pressing hole(ditching),sowing,soil-covering and soil-compacting.