MATERIALS AND METHODS
The present investigations were carried out with full bearing (15 years old) trees of ‘Langra’ (biennial bearing), and ‘Amrapali’ (regular bearing) cultivars of mango during year 2011 and 2012 at Central Institute for Subtropical Horticulture, Rehmankhera, Lucknow located at 26.54oN Latitude, 80.45oE Longitude and 127 m above mean sea level. The potential shoots (50 nos.) were tagged from each direction and fully matured leaves of twigs samples adjacent to apical meristem were collected from each direction for the studies. Sampling was done at different phenological stages of flowering viz. Pre Flower Bud differentiation, Flower Bud differentiation, Bud Burst, Panicle elongation and Full Bloom and fruit growth (Marble, egg and maturity) as per standard procedure (Rajan et al., 2011).
PLANT WATER STATUS
The tree water status was determined by simultaneous measurements of water potential (Ψw) and leaf water content (LWC) in 5 fully expanded leaves from the selected tree. Each excised leaf was immediately put inside zip pouch for Ψw measurement. Water Potential Monitoring System (WP4 & WP4-T Dewpoint Meters, Decagon Devices) was used for determination of Leaf water potential (Turner, 1981). Preliminary experiments were carried out to find the minimum equilibration time required. After equilibration of sample a disc was taken from mid portion of leaf and Ψw was measured. Standard solution of known water potential (Ψw) was always run with samples and values corrected to a temperature of 25oC.
All predawn (7:00-7:30 am) and midday (11:00-11:30 am) Ψw measurements were made with water potential measurement system. Values of LWC were determined as: LWC=100 (FM−DM)/ FM; Where FM is leaf fresh mass and