Performance index: An expeditious tool to screen for improved drought resistance in the Lathyrus genus.

Some species of the Lathyrus genus are among the most promising crops for marginal lands, with high resilience to drought, flood, and fungal diseases, combined with high yields and seed nutritional value. However, lack of knowledge on the mechanisms underlying its outstanding performance and methodologies to identify elite genotypes has hampered its proper use in breeding. Chlorophyll a fast fluorescence transient (JIP test), was used to evaluate water deficit (WD) resistance in Lathyrus genus. Our results reveal unaltered photochemical values for all studied genotypes showing resistance to mild WD. Under severe WD, two Lathyrus sativus genotypes showed remarkable resilience maintaining the photochemical efficiency, contrary to other genotypes studied. Performance index (PIABS) is the best parameter to screen genotypes with improved performance and grain production under WD. Moreover, we found that JIP indices are good indicators of genotypic grain production under WD. Quantum yield of electron transport (ϕEo) and efficiency with which trapped excitons can move electrons further than QA (ψ0) revealed as important traits related to improved photosynthetic performance and should be exploited in future Lathyrus germplasm improvements. The JIP test herein described showed to be an expeditious tool to screen and to identify elite genotypes with improved drought resistance.