| Based on the present seedling nursery methods of cotton, vegetable, and tobacco in domestic and abroad, a new cotton seedling nursery technology, the floating nursing seedling in nutrient water-bed (FNSNWB) is developed by Cotton Research Institute of Hunan Agricultural University. Cotton seeds are sown in patented mix media carried in a porous polyethylene plate which is floated on nourishing water according to the technology of FNSNWB. The seedling emergence of cotton is above 95% and stand rate above 90% by the new method. Compared with other seedling nursing technologies, the FNSNWB has many advantages with low cost, high efficiency, labor-saving and yield increasing. The FNSNWB has achieved greatly and was applied so far in Hunan, Hubei, Jiangxi, Anhui and Xinjiang provinces since 2005. In order to explore the biological base for transplanting the cotton seedlings from FNSNWB with high yield and efficiency, a cultivar Nongza 66 was used as the materials to be investigated the plant performance in the field from seedling to boll opening stages at morphological and physiological-biochemical levels in the present paper.1 Analysis of seedling mophology and physiological and biochemical attributes before and after transplantingThe transplanting experiments showed that the seedlings fostered by the methodof FNSNWB from two to four full-expanded leaves stages were suitable for transplanting into the field, and the best stage was seedlings with three full-expanded leaves.Compared with the method of nutritive bowls nursing seedling (NBNS, control), the fresh and dry weight of shoot, ratio of root to shoot were increased by FNSNWB before transplanting, but reduced after transplanting into the field. The fresh and dry weight of roots, root volume, root length, main root length, radius of root, root area, the first and second lateral roots, leaf area were much more before and after transplanting into the field. So the roots of seedling cultivated by FNSNWB developed greater before and after transplanting into the field. Analysis of seedling roots at physiological and biochemical level showed that the TTC reductive intensity in roots of seedlings with FNSNWB before transplanting were higher than that of the seedling with NBNS. While the TTC reductive intensity in roots of transplants in the field was lower than that of the seedling with NBNS after transplanting into the field for 30 days. The root flooding was lower, but the proline contents in roots were greater than that of the control before and after transplanting into the field. Before transplanting, superoxide dismutase (SOD), peroxidase (POD) activities and malondialdehyde (MDA) contents in roots were higher than the control, while were lower after transplanting into the field for 30 days. Meanwhile, catalase(CAT) activities in seedling roots before and after transplanting into the field were higher than that of the control. The results showed that the activities of SOD and POD in seedling leaves were significantly higher than that of the control, but became lower after transplanting into the field. The MDA content in seedlings leaves were lower before transplanting, but were greater than that of the control after transplanting into the field.2 Comparing of transplanting the seedlings with different treatments at morphological, physiological and biochemical levelsThe results showed that the plant height, fresh and dry weight of shoot of cottonseedlings treated with Gen-te-you and ABT were better than that of two other treatments and control. The ratio of root to shoot of the seedling treated with Gen-te-you were the highest among the four different treatments. The main root length, root length, root volume were increased by Gen-te-you treatment. The largest root area was the ABT treatment, and better the Gen-te-you and media treatments. After transplanting into field, the radius of roots of seedlings treated with ABT and cultural media were reduced when compared with the method of NBNS and other treatments. Compared with control, the fresh and dry weight of shoot, ratio of root to shoot got large before transplanting, but reduced after transplanting into field. The fresh and dry weight of roots, root volume, root length, main root length, radius of root, root area, the first and second lateral roots, leaf area were much more than that of the control before and after transplanting into field.Among the four treatments, the TTC reductive intensity in roots of seedlings treated with Gen-te-you was the highest, and cultural media treatment was the better, which were significantly higher than that of the seedlings cultured by the method of NBNS. There were significant difference between treatments and control in root proline contents, which was no significant difference among different treatments, before and after transplanting into field. The results showed that the SOD,POD and CAT activities in roots of seedlings treated with Gen-te-you, ABT and cultural media were the best among the four treatments and control. The MDA contents in roots of seedlings treated with Gen-te-you, ABT and cultural media were lower than that of the control, and the MDA content in naked roots without cultural media was higher than that of the control. After transplanting into field, the SOD,POD and CAT activities in leaves of seedling treated with Gen-te-you and ABT were the best among the two other treatments and the control. The MDA contents in leaves of cotton seedlings treated with Gen-te-you, ABT and cultural media were lower than that of the control, and the treatment without cultural media was higher than that of the control.3 Cotton plant morphology and yield components in the fieldCompared with the control, the plant roots developed better during the whole growth period, and the fresh and dry weight of roots, main root length, root length, root volume, radius of root, root area, the first and second lateral roots were increased from the stage of seedling to boll opening. The fresh weight of shoot in cotton plants with FNSNWB increased by 43.91%, 88.62%, 49.72%, 37.24%,85.30% and 36.93%, respectively, from seedling to boll opening stage. Meanwhile, the dry weight in shoot of cotton plants with FNSNWB increased by 45.34%, 72.21%, 47.47%, 37.03%, 73.45% and 59.71% , respectively, from seedling to boll opening stage using Nongza 66 as experimental material. In comparison with NBNS, the dates of the first squaring and anthesis of cotton transplants in the field by FNSNWB were earlier from 3 to 5 days, the diameter of cotyledon node were 0.45 cm bigger, the fruiting branches was 2 to 3 more, the boll retention was 8.3% higher, and the squares and bolls shedding were 3.2% lower than that of the control. Therefore, the yield of cotton transplants with FNSNWB in the field was increased by 155.0 kg·hm-2.4 Analysis of physiological and biochemical characteristics of cottontransplants at different growth and development stages in the fieldCompared with NBNS, the TTC reductive intensity in root system fromfirst-flowering to boll opening stages was 2.2%, 6.7%, 12.6% and 20.7% greater, respectively, and the soluble protein and sugar in leaf were obviously higher than that of the control during the whole growth period. The chlorophyll content in leaves of cotton plants raised by FNSNWB was increased and the stomatal conductance was decreased. The transpiration in leaf of cotton plants from seedling to boll-opening stages was 25.9%, 20.1%, 15.9%, 12.8%, 15.5% and 4.2% was lower, while the photosynthetic efficiency were 0.87%, 6.31%, 4.18%, 3.6% and 2.02% from seedling to boll setting stage, respectively, higher than that of the control, the differences was not significant. Meanwhile, the proline and the free amino acid contents and nitrate reductase activity in cotton leaves were increased by FNSNWB.From seedling to squaring stage, the activities of SOD and CAT in cotton roots by FNSNWB were lower than that of the NBNS, but there is no obvious difference. From full bloom to boll opening stage, the activities of SOD and CAT activities in cotton roots by FNSNWB were higher than that of the NBNS. From seedling to boll opening stage, the activities of POD in cotton roots by FNSNWB were higher than that of the NBNS. From seedling to full bloom stage, the MDA contents in cotton roots by FNSNWB were higher than that of the NBNS. However, the MDA contents in cotton roots by FNSNWB were lower than that of the NBNS from boll setting to boll opening stage.Compared with the cotton transplants by NBNS, the activities of SOD in leaves of cotton transplants by FNSNWB were increased by 5.2%,7.5%,8.8%,9.3%,29.5% and 5.8%, respectively, from seedling to boll opening stage. Meanwhile, the activities of POD in cotton leaves were increased by 10.0%,1.3%,5.9%,3.3% and 0.3%, respectively, from squaring to boll opening stage. The activities of CAT in cotton leaves were lower than that of transplants by NBNS, but there was no obvious difference. There is significantly different in CAT activities in cotton leaves between FNSNWB and NBNS at boll opening stage. The MDA contents in cotton leaves were lower than that of the control from squaring to boll opening stage.The content of GA3 in root of cotton transplants were higher than that of the control from early flowering to boll setting stage. Compared with NBNS, the content of IAA in transplant roots were reduced from seedling to squaring stage. And the contents of IAA were higher than that of the control from early flowering to boll opening stage. Meanwhile, the contents of ABA and ZR in transplant roots from seedling to boll opening stage were lower than that of the control. The results showed that the content of GA3 in transplant leaves were lower than that of the transplants by NBNS from seedling to full bloom stage. And the content of GA3 were higher than that of the control from full bloom to boll opening stage. Compared with the transplants by NBNS, the contents of IAA in leaves were increased from seedling stage to squaring stage. And the contents of IAA in leaves of cotton plants from early flowering stage to boll opening stage were lower than that of the control. Meanwhile, the contents of ABA in leaves of transplants from seedling stage to boll opening stage were higher, and the contents of ZR in leaves of transplants from seedling stage to boll opening stage were lower than that of the control.Generally, during cotton whole growth period, the contents of N,P and K in plant roots were higher than that of control. Compared with the transplants by NBNS, the contents of N and P in cotton leaves were increased from seedling stage to boll opening stage. And the content of K in leaves of cotton plants was lower than that of the NBNS, but the difference was not significant.
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