Response of cassava to water deficit: leaf area growth and abscisic acid. Crop Sci

ABSTRACT Walp], maize (Zea mays L.), and several other crop plants (Tardieu and Simonneau, 1998). In addition, leafCassava (Manihot esculenta Crantz) responds to decreases in water area growth is decreased in response to water stressstatus by pronounced stomatal closure and decreased leaf area growth. and is rapidly reversed following the release from stressMany water deficit responses are thought to be regulated by abscisic acid (ABA). To evaluate the extent to which ABA accumulated in (Connor et al., 1981; Palta, 1984; El-Sharkawy and Cock, a temporal pattern related to water deficit and leaf area growth, five 1987). This response limits the development of plant cassava genotypes were grown in greenhouse conditions and subjected transpirational surface area during water deficit and to water deficit and recovery treatments during the vegetative-growth keeps sink demand well balanced with plant assimila-stage. Young and mature leaves were sampled for analysis of area tory capacity. growth and ABA. Under water deficit, leaves from all genotypes A regulatory system that could potentially contributerapidly accumulated large amounts of ABA in both mature and young to cassava’s sensitivity to water deficit is the one involv-leaves. Correspondingly, young leaves halted leaf expansion growth ing the stress hormone ABA. In addition to closingand transpiration rate decreased. Young leaves accumulated more stomates, ABA promotes characteristic developmentalABA than mature leaves in both the control and stressed treatments. changes that can help plants cope with water deficit,The high ABA levels under water deficit were completely reversed to control levels after 1 d of rewatering. This rapid return to control including restriction of shoot growth (Creelman et al.