Photosynthetic characteristics of groundnut (Arachis hypogaea L.) under water deficit stress

Abstract

In a field experiment during summer season, the chlorophyll fluorescence and net photosynthetic rate were studied in six Spanish groundnut cultivars under water deficit (WD) condition between beginning bloom to beginning seed (WD I) and beginning seed to beginning maturity (WD II), by withholding irrigation 31–62 DAS and 62–87 DAS, respectively. The severity of drought was so that the soil moisture content of the stressed field depleted to 9.4 and 6.2 % at 0–15 cm soil depth in WD I and WD II at 62 and 87 DAS, respectively, as against 17 and 19 % in control. The mean RWC of leaves decreased from 92 in control to 88 in WDI and from 91 in control to 84 in WD II with the least decrease in ICGS 44 under WD I and in TAG 24 under WD II. The WD condition significantly increased non-photochemical quenching but decreased the maximum quantum yield of PS II (Fv/Fm) from 0.81 in control to 0.77 under WD I condition which was again resumed to 0.80 after 48 h of withdrawal of stress. The rate of photosynthesis which was 29 and 36 lmol m-2 s-1 in well irrigated plots decreased to 26 and 28 lmol m-2 s-1 with a deduction of 11 and 30 % under WD I and WD II, respectively. Cultivar TAG 24 showed better stress recovering capacity with high photosynthesis under both control as well as WD condition whereas, data on chlorophyll fluorescence parameters showed that cultivar ICGS 44 was least affected to damage via photoinhibitory action.