Leaf Morpho-Physiological Characteristics of Common Bean under Contrasting Moisture Regimes

Some of the morpho-physiological characteristics related to the leaf growth and development of Phaseolus vulgaris L. genotypes have been studied in the field conditions at the Seed and Plant Improvement Institute (SPII). The study was performed as split plot experiment in a randomized complete block design with four replications in well-watered and water deficit conditions with eight genotypes of white، red and Chitti beans. Results indicated that water deficit reduced the number of trifoliate leaves and the reduction in the vegetative stage was greater than the flowering stage. Due to water stress، MCD4011 had the least reduction and COS16 showed significant reduction in leaf numbers in both stages. Leaf angle was affected by irrigation regimes and increased under water deficit condition. White beans showed more than the average in leaf angle. Drought also increased leaf temperature of all genotypes. Genotypes WA4531-17 and KS21486 had the highest specific leaf weight (SLW) and succulence index (SucI) in both irrigation conditions، respectively. Water shortage caused significant decreases in leaf area index (LAI) and relative water content (RWC) in all genotypes. In this condition، AND1007 had higher LAI than other genotypes. The white lines had mean RWC higher than other two groups. Reduction percentages of RWC in genotypes were between 3-10%. Drought stress reduced quantum yield (Fv/Fm) of PSII photochemistry، the lowest decrease was observed in MCD4011 line. Whereas the white lines had the greatest mean proline content in well-watered treatments، but showed the least values of it under stress conditions. Overall، water deficit caused reductions in the most evaluated traits، and increased leaf temperature، leaf angle and proline content of all genotypes up to 2°C، 59% (α=24°) and 105%، respectively.