| In order to provide the theoretical basis for water-saving irrigation of island cotton in Xinjiang, under the natural ecological conditions, using the technology of drip irrigation pipes under plastic film, with the normal irrigation (CK) as control, set up three treatments as 75%, 50%, 25% of the normal irrigation amount, studied the effects of regulated deficit irrigation(RDI) on photosynthesis and chlorophyll fluorescence characteristics in flowering and boll-forming stage of island cotton,. The results showed that: The peak of photosynthesis of island cotton appeared at 30 days after flowering, at this time with increasing RDI degree, the transpiration rate (Tr) will be significantly decreased. The net photosynthetic rate (Pn) and stomatal conductance (Gs) did not significantly decrease by the mild RDI (W1), but they were significantly declined by the moderate (W2) and severe RDI (W3). After flowering 10～30 days, the actual light quantum yield (ΦPSⅡ) and coefficient of photochemical quenching (qP) will be significantly increased, but with increasing RDI degree, the maximal photochemical efficiency (Fv/Fm) and ΦPSⅡ will be significantly decreased. After flowering 30 days, the W1 treatment compared with CK the Fv/Fm, ΦPSⅡ, qP, NPQ did not significantly decrease, but the W2 and W3 treatments significantly decreased. Therefore, through analysis, we considered during 30 days after flowering of the island cotton was unsuitable to carry out RDI, and after 30 days it can be carried out the mild RDI. |