Study On Effects Of Regulated Deficit Irrigation On Growing, Physiological Indexes And Yield Effects Of Alfalfa

The effects of regulated deficit irrigation on growing, physiological indexes and yields effects were studied in Qinwangchuan irrigation regions both in 2004 and 2005. The alfalfa (Medic ago sativa L.cv) in the whole stages was subjected to varying levels of water deficit in 2004 as follows: free from water deficit (soil water content, CK, maintained at 65 to 70% of the field capacity), light water deficit (LD, maintained at 60 to 65% of the field capacity), medium water decifit (MD, maintained at 50 to 60% of the field capacity) and high water decifit (HD, maintained at 45 to 50% of the field capacity). The treatments in 2005 were directed to water decifit (50% of the field capacity) in different stages: CK means free water deficit, FF means water deficit from re-emerging to branching stage, FX means water deficit from branching stage to squaring stage, and XK means water deficit from squaring stage to blooming stage. The results showed as follows:(1) Growing characteristicsThe tendency of curve of height-day of growth increased under every treatment. There was no significance about height at the end of the first cutting and the third cutting. The height in the first cutting was the highest and the third cutting was the shortest in all treatments.The leaf area index (LAI) was related to the day of growth obviously in one cut, and there was a significant linear correlation between height and LAI. The LAI in the first cutting was the highest and it decreased from the first cutting to the third cutting in all treatments. And those were significant at p<0.01 level among the treatments.There existed logarithm relations between the layer weight of roots and soil depth with the correlation factor of over 0.9623. The weight of roots decreased rapidly with the increase of soil depth. And the roots mainly distributed in the upper 30cm. In addition, the root/shoot was studied and put forward to two new conceptions named"Grass Average Root/Shoot Ratio"and"Grass Border Root/Shoot Ratio".(2) Physiological characteristicsThe whole course of Diurnal transpiration rate of alfalfa under different water...