| Simplified cultivation is the development direction for cotton production. This study evaluated the effects of three new simplified cultivation methods on cotton physiological indices during the recovering period, cotton yield and fiber quality, compared nursery costs and benefits of these three methods, and therefore, might presumably provide technical and theoretical support for extension of seedling transplant methods. Three methods (Soilless-substrate naked-seedling and transplant, Floating nursing seedling in nutrient water-bed and transplant, Plug seedling and transplant) were compared in physiological indices, yield and fiber quality after transplant. Both seedling nursing experiment and transplanting experiment were arranged with complete randomize block design. The experiment with respect to irrigation and transplant time was arranged with sub-split plot design with 3 replications, taking 3 transplanting dates (April 24th, April 28th and May 13th) as the main plot and 4 irrigation rates (0, 500, 1000 and 1500kg plot-1) as sub-plot. The results indicated:(1) The seedling survival rates with respect to 3 methods were fairly the same. Nursery cost per plant was the greatest (0.071yuan·plant-1) for water floating seedling, followed by substrate seedlings (0.045 yuan·plant-1) and plug seedlings (0.040 yuan·plant-1). The seedling survival rates reached to 100% after transplant with film mulching for all 3 methods.(2) Compared with plug transplant and water floating transplant seedlings, substrate seedlings were greater in chlorophyll content, MDA content, SOD activity, CAT activity, POD activity after transplant due to the stress, however, in the end of the recovery period, there was no difference between 3 methods in those indices. The recovery period of two experiments was 9 days and 14 days for substrate seedling transplant, 5 days and 7 days for plug seedling transplant, and 5 days and 10 days for water floating seedling transplant.(3) Water floating seedlings had the greatest plant dry weight and leaf area in either nursery or after transplant. The difference was still significant even after 18 days after transplant. Water floating seedlings and plug seedlings grew fast in the early period after transplant, and the root with respect to them were longer than the root of substrate seedlings, however, there was no significant difference in root length for all three methods 18 days after transplant,.(4) There were significant differences among the three methods in seed cotton yield. Substrate raised seedlings had the greatest seed cotton yield with 3793.5 kg·hm-2, followed by plug seedlings (3493.5 kg·hm-2) and water floating seedlings (3211.5 kg·hm-2). Water floating seedlings had the lowest yield due to senescence and greater rot bolls. The greatest boll weight was found in plug seedlings, followed by substrate raised seedlings. There was no difference between 3 methods in lint percentage.(5) Variation trends of chlorophyll content, MDA content, SOD, CAT, and POD enzyme activity were similar for different transplanting dates and irrigation rates during the recovery period. Seedlings transplanted on April 24 and April 28 with non-sowing irrigation were damaged greatly due to water stress and low temperature after transplant, and were greater in the chlorophyll content, MDA content, proline content and SOD activity. With the same transplanting date, there was no difference observed between irrigation rates on recovering date.(6) For seedlings transplanted on April 24, the irrigation rate of 500kg and 1000kg were greater in seed cotton yield, lint yield and boll weight, however no statistical differences were observed among irrigation rates. For seedlings transplanted on April 28, the irrigation rate of 1500kg was the greatest, and no irrigation was the lowest in seed cotton yield and lint yield; however, no significant differences were observed among treatments. Under the same irrigation rate, seed cotton yield, lint yield and early season flower were the greatest for the transplanting date of April 28th. The combination of transplanting date April 28th and irrigation rate 1500kg was the best one.(7) Fiber quality indices (fiber length, uniformity, micronaire, elongation and strength) with respect to different irrigation rates and different transplanting dates were not significantly different.
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