Photosynthetic and physiological responses to drought of Jerusalem artichoke genotypes differing in drought resistance

Abstract

Plant physiological and photosynthetic responses to drought among Jerusalem artichoke genotypes possessing different levels of drought resistance are still lacking. We investigated the physiological and photosynthetic responses to drought of six Jerusalem artichoke genotypes differing in drought-resistance levels and evaluated the contribution of physiological and photosynthetic traits to tuber yield under drought condition. The split-plot in randomized complete block design with four replications was used. Six Jerusalem artichoke genotypes as sub-plots were nested in two water regimes (100% ET and 50% ET) as main plots. Relative water content (RWC) was recorded at 30, 60, and 90 days after transplanting (DAT), while SPAD chlorophyll meter reading (SCMR), net photosynthetic rate (Pn), stomatal conductance (gs), and leaf area (LA) were recorded at 30 and 90 DAT. Biomass and tuber yield were recorded at harvest stage. Water deficit restricted RWC by 20.45%, LA by 23.29%, Pn by 9.87, gs by 40.315, biomass by 42.62, and tuber yield by 46.13%, yet increased SCMR (6.74%) of six genotypes. The reductions observed on all traits of drought-resistant genotypes were smaller than that of susceptible genotypes. A drought-resistant genotype KT 50-4 showed a low tuber yield reduction (36.59%) and LA (16.34%) under water deficit condition, whereas KT 50-4, JA 60, and JA 125 had low reductions of Pn (7.06–9.75%) and gs (15.40–42.86%) under water deficit condition. While LA had a significant contribution to tuber yield under fully irrigated (80.11%) and drought (85.57%), Pn and SCMR had smaller contributions to tuber yield under drought condition (3.73% and 12.65%). Our results indicated that improvement of LA could contribute to high tuber yield under limited water conditions.