1995 Volume 39 Issue 4 Pages 223-228
This experiment was conducted to study varietal differences in dry matter increment (W) and water use efficiency (WUE) using eight chilli pepper cultivars under greenhouse condition. Treatments were daily irrigation levels of 100% (Control: C) and 40 to 50% (Dry: D) of the daily evapotranspiration (ET) of the control. Significant varietal differences in W and WUE were observed. The coefficients of variation were ranged from 21.4% (C) to 31.5% (D) for W, and from 17.9% (C) to 31.5% (D) for WUE. A greater varietal difference in the water stress treatment than in the control was observed for both W and WUE. There was a significantly positive correlation between W and WUE, and also a closely positive correlation was noted between WUE and the net assimilation rate (NAR) . These results suggested that the varietal difference in W was strongly controlled by NAR through WUE regardless of the presence of water stress. The cultivar with a higher NAR also displayed a higher WUE and a greater W. NAR showed a closely positive correlation with evapotranspiration per mean leaf area (ET/LA) in the control, but it didn't showed a significant correlation in the water stress treatment. However the results of multiple regression analysis showed that NAR in the water stress treatment was controlled by both ET/LA and the mean dry weight of non-photosynthetic organs per mean leaf are (CW/LA), and the coefficient of multiple regression was signifi-cant. Ratio of standard partial regression coefficient, which indicates the ratio of contribution of ET/LA and CW/LA to NAR, was 60% for ET/LA and 40% for CW/LA. These results suggested that varietal difference in NAR was restricted by the photosynthetic rate in the absence of water stress, although it was controlled by the photosynthetic rate as well as by factors that were related to respiration in the case of water stress.
