Studies on the Effect of Water Stress on Root Traits in Green Gram Cultivars

Abstract

Background: Green gram is one of the important pulse crops of chief protein source, with ability to fix nitrogen. Erratic rainfall, while it’s grown as rainfed crop, leads to the yield loss due to water stress. Plant root system architecture is plastic and is important sink of photosynthates. In general, the ability of plants to change its root distribution for exploiting water deeper in soil profiles can be an important mechanism to avoid soil water stress. Identification of genotypes based on root traits under water stress conditions will aid in development of drought tolerant varieties for yield exploitation. Methods: The experiment was conducted during Rabi, 2018-19 with five green gram varieties as main treatment and irrigation intervals as sub treatments in three replications in factorial RBD in root structures. Observations were recorded on root parameters at flowering stage. The root structures were dismantled during flowering stage and all the plants removed from the soil without damaging the roots by using water with jet pump. Five representative samples were collected under different stress level. Root studies were performed with Delta T automatic root scanner. The SPAD chlorophyll meter was used to measure canopy leaves and average of the three readings was taken as SCMR value. Result: The present study results on root studies revealed that genotype, MGG-295 recorded highest mean plant height under three stress conditions and same genotype also produced longer root length under mild water stress conditions, higher SCMR values under non-stress and mild stress. Genotype, MGG-347 recorded highest root diameter under non- stress and mild stress. MGG-385 produced highest root length under control and severe stresses, highest SCMR values under severe stress, root dry weight under mild and severe water stresses and total plant dry weight under control and mild stress. MGG-360 recorded higher shoot fresh weight under severe stress and same genotype also recorded significant superior values for total root area under mild and severe water stress and root tip count under non-stress, mild stress and severe stress. MGG-351 recorded shoot fresh weight under non stress and mild stress situations and the same genotype recorded highest values for root diameter and total plant dry weight under severe stress. The identified genotypes can be used as water stress resistant genotypes in future drought proof breeding programmes.