Effects Of Transgenic-Cotton-Specific Plant Growth Regulator On Transgenic Cotton (Gossypium Hirsutum L.) And Its Physiological Basis

Effects of a Transgenic-Cotton-Specific Plant Growth Regulator (mixture of Mepiquat Choloride and Diethyl amino ethyl caproate Hexanoate, SPGR) on transgenic cotton (Gossypium hisutum L.) and its physiological basis were studied under field and greenhouse condition, using NuCOTN99B, CCRI30, SGK321 and its recurrent parent Shi Yuan321 as materials. The main result were as following:1. The application of SPGR promoted the seed germination of CCRI30 by accelerating the growth of hypocotyls, the elongation of primary root and the emergence of lateral root primordial. A long term strong apical dominance was kept by high-levels of growth-promoting hormones in roots and apical buds. SPGR increased photosynthesis ability of seedlings to ensure the development of source organ by increasing the gross leaf area and chlorophyll content of functional leaf, and ameliorating the ultra-structure of chloroplast.2. SPGR application increased the lint yield of transgenic cotton SGK321 and NUCOTN99B by 24.33% and 37.00%, increased the boll No. 30.35% and 10.82%, an d enhanced the boll weight of SGK321 by!3.05%. The ratio of 5-carpel boll and the seed index showed +10.41% and 11.95% higher on SGK321, and number of sterile seed was found reducecd on NuCOTN99B. In addition, strike increase of fiber strength, length and micronaire value indicated that fiber quality of transgenic cotton was also improved. As a whole, the positive effect by the coordination of DPC and DTA-6 was observed in this study.3. Non-coordination of source-sink relation of transgenic cotton SGK321, compared with ShiYuan321, was due to the lower absorption ability of the roots, the weaker photosynthesis of the leaves and the slower assimilation (sucrose mostly) transportation from leaves to root and boll-sink. All the roots activity, concentration of free amino acid, nitrate nitrogen, phosphorus and potassium element, IAA and Z+ZR in xylem exudates, the contents of sucrose and soluble protein in functional leaves were increased significantly, while malonadehyde content in functional leaves was decreased. The above changes promoted materials supplying for roots system and boll development, and further led to delayed senescence of leaves and roots, speeding up of boll development.From the data, the promoted development of root-source and leaf-source and the coordinated Source-Sink relation may explain the physiological basis of the lint yield increase and the fiber quality improvement of the transgenic cotton after SPGR application.