Assessment of water relation traits during different phenological stages in mango (Mangifera indica L.)

In mango, water stress plays an important role in flowering & fruiting regulation as it provides the floralinduction signal. Pressure volume curve (P-V curve) was used to derive basic water relation parameters, viz., osmotic potential, symplastic and apoplastic water content, solute potential at full turgor, turgor loss point, water content at turgor loss point and elasticity modulus in plant system. In the present paper Amrapali and Langra mango cultivars having regular and irregular bearing habit, were studied in order to understand the leafresponses to different water status. The effect of paclobutrazol (PP₃₃₃), a growth retardant having anti-gibberellinactivity and induce the flowering even in the ‘Off ’year on these parameters was also studied. During flowerbud differentiation (FBD), Amrapali had more osmotic potential (−3.39 MPa) than Langra (−5.38 MPa) without anysignificant shift with paclobutrazol treatment. However, osmotic potential increased markedly in trees treatedwith paclobutrazol (2 g a.i./tree) at flower bud burst and panicle emergence stages as compared to control. Langra exhibited lower turgor loss point (−5.56 MPa) than Amrapali (−5.41 MPa) at FBD, which indicate earlyturgor loss in leaves of Langra than Amrapali during the critical period of flowering. Amrapali showed lowerturgor loss point (TLP) in subsequent stages of flower development, which may signify that with lower TLP itmay be able to maintain osmoregulation at lower leaf water potentials. Sap flow also varied significantly in thesecultivars as Amrapali had higher range of sap flow (6.76–18.99 kg/h) than Langra (6.91–13.11 kg/h) in differentflower developmental stages. The results of this study showed that adjustment for water stress may be greaterin Amrapali than Langra sharing same habitat but having different bearing pattern. Better osmoregulation maybe helpful for Amrapali to outgrow better than Langra under subtropical conditions.