Preliminary Study On The Effect Of The Technique Of Seedling Soilless-raising And Root-naked Transplanting Of Cotton

The technique of seedling soilless-raising and root-naked transplanting without root-supporter of cotton (is called SSR-RNT for abbre) was the research findings of the cotton comprehensive and high-efficient production research group of institute of CAAS.This preliminary study was one of the continuous works of the many years research, and was aim to discover more about its practical effects and to perfect its operation specification.In this study, the compare of practical effects of the root regulator and rootone ABT4, the test for right irrigation times of the root regulator, the compare of the growth quality of seedlings raised by several soilless ground substances of different nutrient composition, and the test for the right amount of nutritive substance to fertilize the soilless ground substances of the SSR-RNT were carried out. The right time for seed sowing and seedling transplanting was discussed throughout the test of the compare of different seedtime and transplanting time and the investigation of biological indicators in different cotton growth periods. In the last, the integrated operation specification, which was taken from the integrated application of the results of the former tests, was applied in different cultivation models and cultivated variety in order to study the effect of this technique on the physiological and biological indicators of cotton and to search after the application method of this technique in different cultivation models.The main results were outlined as below.The effect of the root regulator was better than rootone ABT4, and the right irrigation time was one time each in cotyledon open period and one euphylla period before transplanting. The cotton seedling grew better in seedling bed when the amount of the three nutritive substance X₁, X₂, X3 each reached 8.39⁹.32kg/m3, 0.81⁰.90kg/m3, 1.26⁴.15kg/m3 in the soilless ground substances of the SSR-RNT, and it was easy to get the effect of sound seedling and early development of cotton plant.The right seedtime was from the end of March to the early of April when soil moisture was sufficient. It need 3⁵ days of good weather after transplanting.In different cultivation models, the SSR-RNT cotton had the characteristic of fast growing in the primary stage and no presenility in late stage. The dry matter weight and leaf area per cotton plant of the SSR-RNT cotton was lower than that of the direct sowing in the primary stage, and was higher than that of the direct sowing and the seedling raising and transplanting by nutritive pot. It was in accord with the features that the SSR-RNT cotton represented in fields which were that steady growth in the primary stage, fast growth in the mid-late stage and no presenility in late stage. The content of chlorophyll in leaf of the SSR-RNT cotton was higher in the late stage. The change of the content of MDA in leaf of the SSR-RNT cotton discovered that the SSR-RNT cotton had advantage of in the mid and late stage.There was no significant difference between the SSR-RNT model and other cultivate model in the yield and quality. But the benefit of the SSR-RNT cotton was very different from that of the others.