Photosynthetic efficiency of bottle gourd [Lagenaria siceraria (Molina) Standl.] under drought stress

Abstract

Neglected and underutilized crops such as bottle gourd [Lagenaria siceraria (Molina) Standl.] are associated with considerable drought tolerance. The objective of this study was to determine variation in the level of drought tolerance among bottle gourd landraces based on photosynthetic efficiency and to identify unique genotypes for breeding. Photosynthetic efficiency of 12 selected bottle gourd landraces were evaluated under controlled environment under drought-stressed (DS) and non-stressed (NS) conditions. A significant genotype × water regime interaction (P < 0.05) was observed for minimum fluorescence (Fm′), maximum quantum efficiency of PS II photochemistry (Fv′/Fm′), the effective quantum efficiency of PS II photochemistry (ΦPSII), photochemical quenching (qP), non-photochemical quenching (qN), linear electron transport rate (LETR), non-cyclic electron transport rate (NCETR), proportion of open PS II reaction centers (1 − qP), photo-inhibition of PS II reaction centers Y (NO), the fraction of photon energy trapped by “open” PS II reaction centers and utilized in PS II photochemistry (P), the portion of the absorbed photon energy that was thermally dissipated (D), rate of photochemistry (RPC) and rate of heat dissipation (RHD) suggesting variation in genotypic response under NS and DS conditions. Principal component analysis under NS and DS conditions identified two principal components (PC’s) which accounted for a total variance of 90 and 96%, respectively. Under DS condition, minimum fluorescence (F0′), Fm′, Fv′/Fm′, qN, NCETR, D, and RHD correlated with PC1 which accounted for 56% of total variation. ΦPSII, qP, LETR, P, RPC and 1 − qP correlated with PC2 which accounted for 40% of total variation. The PC biplot identified landraces BG-27, BG-58 and BG-78 as the most drought tolerant characterized by high values for LETR, qP, P, ΦPSII and RPC under drought stress condition. These landraces could be a useful genetic resource in the development of bottle gourd genotypes with enhanced drought tolerance.