Laxman R.H.

• Evaluation of banana genotypes for tolerance to limited water stress showed genotype Behee kela recorded higher photosynthesis rate (7.7 μ mol m-2 s-1) followed by Kach kela and Calcutta-4. Studies on root characteristics also showed genotypes Beehee kela and Kachkela (both BB) had higher root mass to shoot mass, average number of roots and total root length per plant compared to Calcutta-4 (AA). Both the genotypes belonging to BB genome with higher root mass relative to the shoot mass, higher number of roots and total root length per plant were better adopted for withstanding limited water stress conditions.

• In the study on making annona scions available for round the year grafting, spraying 10% urea caused not only defoliation but also enhanced subsequent sprouting of sub-petiolar buds, leading to production of graftable shoots in six months.

• In Mango cv. Alphonso high density orcharding, light interception by the canopy of paclobutrazol treated trees was at par with non-paclobutrazol treated trees, though with small tree size. Paclobutrazol treatment reduced vigour, increased leaf to stem area ratio and leaf area per tree leading to higher proportion of exposed leaves in the canopy. Light availability at different levels of the canopy was also quantified.

• Grapes, cv. Flame Seedless trained on Y trellis training system the gas exchange characteristics of the leaves receiving different light levels in the canopy was quantified. Exposed leaves in the canopy had highest photosynthesis rate (9.11 μ mol m-2 s-1). Leaves lower in the canopy received PAR around 260 μ E m-2 s-1 had photosynthesis rates only 42% of the exposed leaves. But the rates of transpiration (90.68%) and stomatal conductance (70.81%) were still high. Though shaded leaves contributed photosynthates the higher transpirational loss caused reduced instantaneous water use efficiency. Maintaining seven leaves per shoot beyond bunch under Y trellis system enhanced interception and better light availability in the canopy.

• In passion fruit, only completely exposed and partially exposed leaves contributed photosynthates and leaves positioned lower in canopy under complete shade (receiving PAR around 50 µE m-2 s-1) were found to be parasitic on the vine. It is suggested to avoid mutual shading within the canopy to enhance canopy light use and photosynthetic efficiency.