新疆内陆干旱区不同灌水量对长绒棉光合特性的影响

为探索新疆内陆干旱区不同灌水量对长绒棉新海14号光合特性的影响,利用小区试验,在5种灌水量(W)条件下,对其光合特性进行研究。结果表明:灌水量为7650m3/hm2时,叶片净光合速率日变化呈单峰曲线;随着灌水量的降低,其净光合速率日变化呈双峰曲线。新海14号的光补偿点为50μmol/m2·s;灌水量为2850(m3/hm2)时,其光饱和点为310μmol/(m2·s),灌水量为5475m3/hm2以上时,其光饱和点为1280μmol/(m2·s)。叶片的净光合速率及蒸腾速率随灌水量的升高而增加,气孔阻力随灌水量的升高而降低。水分利用效率随着灌水量的降低而提高,呈极显著负相关;棉花产量对灌水量极为敏感。净光合速率与蒸腾速率呈显著正相关,与气孔阻力呈极显著负相关;蒸腾速率与气孔阻力呈显著负相关。新海14号的光合作用最适宜灌水量为6945m3/hm2;灌溉的临界值为5250m3/hm2。

A Effect of Irrigation Quantity in Xinjiang Arid Region on Photosynthesis Characters of Long - fibre Cotton

The research for studying the Xinjiang arid region on photosynthesis characters of Xinhai 14Long-fibre Cotton under conditions of five artificial irrigation droughts. The result showed under the different conditions of irrigation , when W was 7 650 m3/hm2 , the curve of diurnal variation of leaf photosynthesis showed single peak, with the irrigation quantity dropping .The curve of diurnal variation of leaf photosyn thesis showed two single peak. The light compensation point of photosynthesis of Xinhai 14 Long-fibre Cot-ton leaves were 50 μmol(m2·s);when W were 2 850 m3/hm2,the light saturation point of photosynthesis of Xinhai 14 Long-fibre Cotton leaves were 310 μmol(/m2·s), when the W was 5 475 m3/hm2 and over the light saturation point were 1 280 μmol(m2·s).The leaf net photosynthesis(Pn) rate and transpiration rate increased with the raise of irrigation quantity,the stoma resistance drooped with the raise of irrigation quantity. The water use effciency (WUE) raised with the dropping of irrigation quantity. The yield of cotton wasthe most sensitive to irrigation quantity.Positive correlation appeared between the net photosynthetic rate and transpiration rate .There was a significant negative correlation between Pn and the stoma resistance.The optimum irrigation quantity of Pn was 6 945 m3/hm2,at which the plant needs irrigation quantity,was 5 250 m3/hm2.