Constant water table sub-irrigation of pots allows derivation of root weights (without physical recovery) and repeated measures of in situ growth and water use efficiencies

Abstract

We examined novel ways of non-destructively measuring root weight, plant growth and water use efficiencies to improve the detection of treatment effects in plant phenotyping in pot culture. Two genotypes each of maize, sunflower and soybean were grown in 4 L ANOVApot®s in the Twinpot Water Management System (TWMS) of a constant water table. Measurement of pot weights and pot water losses (weekly and by drip rate) over time allowed the derivation of plant biomass gain and Water Use Efficiences (WUE). The destructive harvest at 31 days provided weights of plant parts and derived estimates of fresh root weight without physical recovery. Derived estimates of whole plant biomass were highly correlated with harvested whole plant dry weights (r = 0.97) and fresh shoot weights (r = 0.99), while estimates of non-recovered fresh root weights were highly correlated with harvested shoot fresh weights (r = 0.86) and recovered root fresh weights (r = 0.85). WUEs based on actual water loss and drop counts varied significantly across species and between maize cultivars. Constant water table plant culture in pots allows measures of roots without physical recovery, in situ crop growth and WUEs based on water losses and drip rates.