Abstract:

【Objective】 The objective of the study is to understand the photosynthetic characteristics and water use efficiency of sweet sorghum under different land types. 【Method】 Three land types which are loam land, saline-alkaline land and sandy land were selected for studying adaptability of sweet sorghum in middle oasis region of Hexi Corridor, and the gas exchange parameters were measured at jointing stage. 【Result】 The daily variation of leaf photosynthetic rate of sweet sorghum showed a unimodal trend without a midday depression under different land types. Compared with loam land, the net photosynthetic rate and water use efficiency had some decreasing under saline-alkaline land and sandy land, the net photosynthetic rate was (30.75±4.31), (25.31±4.43) and (23.71±3.86) μmolCO2?m-2?s-1,leaf water use efficiency was (5.42±0.98), (4.34±0.55) and (3.08±0.31) μmol CO2?mmol-1H2O, biomass water use efficiency was 3.48, 3.21 and 2.17 kg?m-3 under three land types, respectively, but no significant difference between saline-alkaline land and loam land. The transpiration rate was maximum in sandy land, it showed that the leaf temperature of sweet sorghum reduced by higher transpiration rate, and then adapted this climate condition with higher temperature and stronger radiation.【Conclusion】From resolving energy and ecological crisis, and economizing land resources, the saline-alkaline land and sandy land in arid region are fit for development of sweet sorghum; but if the higher biomass yield and water use efficiency want to be acquired in marginal land, the soil physical and chemical properties or cultivated modes should be improved, and then acquiring high yield and economizing water resources.

Key words: land types, photosynthetic characteristics, water use efficiency