The general equations available/developed for forest/wild mango trees based on measurement of diameter at breast height (DBH) (cannot be used) are not applicable for mango orchards which are predominantly established with grafted plants. Hence allometric equations were developed with destructive sampling of grafted mango trees. The selected parameters showed that allometric parameters were significantly related with age of the trees. The proportion of roots (22%) in grafted mangos was found to be higher than those reported for tropical forest trees (18%) with a R ratio of 0.291. The biomass expansion factor (BEF) varied with age. Initially the BEF was very high followed by a decreasing phase and finally a steady phase by and large attained stability beyond 20 years. The equations generally fitted the data well, and in most cases more than 50% of the observed variation in biomass was explained by primary branch girth (PBG) × number of primary branches (NPB). All equations were statistically significant (p < 0.05) for both scaling parameters, a and b. Based on the R 2 values the best fit model for estimation of above ground biomass of grafted mango trees is a power model using PBG × NPB as the best dimension: There was a good agreement between the observed and the predicted biomass using this equation.
In summer seasons of 1991 and 1992 the gas exchange and leaf water relations were analysed in two peanut cultivars: drought tolerant cv. GG 2 (DT) and drought sensitive cv. JL 24 (DS). Soil moisture stress was imposed by withholding irrigation at pod development phase. The decrease in photosynthesis (PN) under stress was associated with a decrease in stomatal conductance (gs) and relative water content (RWC). The PN and RWC were significantly higher under stress in DT than DS. On relief of stress the gs and RWC recovered more quickly in DT than DS. The maintenance of higher RWC (>80 %), gs and PN under stress appears to be imparting drought tolerance in peanut.
Transient soil-moisture-de®cit stress was imposed on groundnut (Arachis hypogaea) at three phenophases for dierent durations: long stress in the early vegetative phase (20 days after sowing); moderate stress in the early vegetative phase (20 days after sowing); stress at¯owering (40 days after sowing); and stress at pod development (60 days after sowing). Stress was imposed for 30 or 25 days at the vegetative stage. Transient soil-moisture-de®cit stress, at all phenophases, reduced the production of¯owers. Soil-moisture-de®cit stress for 25 days at the vegetative phase followed by two relief irrigations at an interval of 5 days, resulted in closely synchronized¯owering. This factor contributed to a greater eciency of conversion of¯owers to pods and to higher pod yields. Total biomass accumulation was also higher in plants which experienced stress in the vegetative phase. Groundnut pod yields were increased by imposing a transient soil-moisture-de®cit stress in the vegetative phase for 25 days, followed by two irrigations at an interval of 5 days. Thus stress in the vegetative phase was bene®cial for groundnut growth and pod yields, but was highly detrimental when imposed at¯owering and pod development.
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