A Study On Morphological And Photosynthetic-physiological Characteristics Of High Yield Hybrid Variety "xinluzhong 31"

A field study, which focused on the morphological and photosynthetic-physiologicalcharacteristics of high yield hybrid cultivar "Xinluzhong 31" which is widely adopted in South Xinjiang., was conducted in Alar Farm (40°50'N,80°40'E) in 2006-2007. The objective of this research is that the high yield mechanism can be explained through the investigating agronomic development process, dry matter accumulating, photosynthesis and yield constituting factors, and that theory and technology for high yield can be supported.Under high yield condition, the net photosynthetic rate and transevaporation for Xinluzhong 31 during bud growth phase and boll development were 24.93μmol·m-2·s-1,12.13mmol·m-2·s-1and 25.48μmol·m-2·s-1,18.62mmol·m-2·s-1 respectively, which were significantly higher than that for contrast cultivar. The correlative and path analysis results showed that the biggest contribution for high yield of Xinluzhong 31 was net photosynthetic rate, and the second and third position were occupied by photosynthetic active radiation (PAR), transevanporation and water use efficiency, respectively..The high yield optimal density for Xinluzhong 31 is 20.0456 plants·hm-2 in Southern Xinjiang. The contribution order to yield for Xinluzhong 31 are density> boll number per plant> boll weight> lint percentage among different yield factors. Therefore, The chemical regulation using mepiquat chloride (DPC) was significantly effective for developing idea cotton plant morphology. Under high yield condition, the plant height was regulated in range of 90-100cm using DPC 375g-hm-1, average length of stem internode 5.5 to 6.0 cm, the effective sympodium branch numbe 6 to 7, boll number per plant 8.5 to 11, boll weight 3.98 to 4.12g, lint percentage 38.8-40.6%, seed cotton yield can reach to 8250 to 9030 kg-hm-2. The optimal period for tip pruning is between 8-18 July for "Xinluzhong 31" in south Xinjiang, plant height is no more than 95 cm, sympodium branch number is 9 to 10, the total sympodium point 26-28, the effective bolling percentage about 48%.