Reju M. Kurian

Long-term effects of rootstocks on growth and fruit yielding patterns of ‘Alphonso’ mango (Mangifera indica L.)

Abstract Results of a 21-year study on the performance of ‘Alphonso’ mango grafted on eight rootstocks established the influence of the rootstocks on the growth and fruit yielding patterns of ‘Alphonso’ scion. Nucellar seedlings of ‘Muvandan’ ‘Bappakai’ and ‘Olour’ were vigorous rootstocks in decreasing order of vigour, while those of ‘Vellaikulamban’ imparted dwarfing, in comparison with the scion grafted on its own open-pollinated zygotic seedlings. The cumulative fruit yield per tree was higher on the vigorous rootstocks, particularly ‘Muvandan’ and ‘Olour’; the latter rootstock also resulting in early higher yields of the scion. However, the fruit yields per unit canopy volume and per unit land area were higher with the dwarfing ‘Vellaikulamban’ rootstock. Based on the analysis of variance and game theory analysis of growth and yield data of several years, nucellar seedlings of ‘Vellaikulamban’ and ‘Olour’ were suggested as potential rootstocks for intensive cultivation of ‘Alphonso’ scion. Correlation studies indicated trunk cross sectional area to be a good indicator of vigour in mango and cumulative fruit yield during the initial 16 years was highly correlated with that during the subsequent years. The bienniality parameters worked out with the yield data over a number of years suggested ‘Alphonso’ to be of irregular bearing nature which was controlled more by exogenous factors than endogenous ones and slightly influenced by the rootstocks.

Stem anatomical characters in relation to tree vigour in mango (Mangifera indica L.)

Abstract Studies conducted with 24 mango cultivars of widely varying vigour indicated that low vigour of trees was associated with a higher primary phloem to primary xylem ratio in young shoots. Width of cortex or pith did not show any relationship with tree vigour. There was no significant difference among the cultivars with respect to the number of xylem vessels or size of metaxylem vessels. Higher phloem to xylem ratio was also observed in the case of trees of cultivar ‘Alphonso’ dwarfed by the external application of paclobutrazol mainly due to fewer xylem vessels and smaller diameter for the metaxylem vessels. The radial width of half pith was also drastically reduced by the chemical but those of cortex and phloem were unaffected. Since there was significant negative association of phloem to xylem ratio with tree vigour and size, this character could possibly be employed in the early screening of genotypes for tree vigour.

Growth, yield, fruit quality and leaf nutrient status of thirteen year old ‘Alphonso’ mango trees on eight rootstocks

SummaryNucellar seedlings of mango cv. Vellaikolamban were dwarfing when used as a rootstock for cv. Alphonso scions, while those of cvs Muvandan, Bappakai and Olour behaved as vigorous rootstocks, in decreasing order. There was more flowering, and less vegetative flushing when ‘Alphonso’ was grown on this dwarfing rootstock. An inverse relationship between the phenolic content of stem apical buds of the scion and tree size was observed. Differences in leaf nutrient status of ‘Alphonso’ on the various rootstocks were significant for N, K, Fe, Ca, Mn, and Cu, but not for P, Mg and Zn. Vigorous rootstocks led to higher leaf N contents and the least vigorous rootstock resulted in the lowest values of N, K, and Fe. The highest content of the last two nutrients were also recorded on the vigorous rootstocks cvs. Olour and Muvandan. Although fruit yield per tree was high on the vigorous rootstocks and low on cv. Vellaikolamban, productivity, expressed as fruit yield per unit space occupied by canopy, was higher ...

Chemical regulation of tree size in mango (Mangifera indica L.) cv. Alphonso. I. Effects of growth retardants on vegetative growth and tree vigour

Effects of soil drenching with paclobutrazol and foliar sprays of Cycocel and Alar were assessed over two successive years as a means of chemically dwarfing young mango trees. Treatments were imposed either once or twice, just prior to vegetative flushing. All treatments suppressed vegetative flushing, shoot length and leaf number and area. Paclobutrazol was the most effective; the highest dose (10.0 g per tree) practically arrested tree growth but had some phytotoxic effects. At 2.5 or 5.0 g per tree there was more than 50% reduction in tree volume expansion, with no phytotoxicity. Higher doses of Cycocel and Alar also checked tree volume but the effects persisted only for one season.

Chemical regulation of tree size in mango (Mangifera indica L.) cv. Alphonso. II. Effects of growth retardants on flowering and fruit set

Effects of soil drenching with paclobutrazol and foliar sprays of Cycocel and Alar on flowering and fruit set of nine year old mango trees were assessed for two successive years. Early and profuse flowering was a striking response to paclobutrazol treatments. Cycocel and Alar slightly increased flowering in first year and reduced flowering in the following year. Treatments resulted in condensed panicles, an enhanced proportion of hermaphrodite flowers and tended to reduce pollen fertility. Fruit set was promoted by 2.5 g paclobutrazol per tree. Fruit retention was not promoted by any of the treatments, but the highest concentration of paclobutrazol (10 g per tree) had a detrimental influence both on fruit set and retention.

Chemical regulation of tree size in mango (Mangifera indica L.) cv. Alphonso. III. Effects of growth retardants on yield and quality of fruits

Effects of soil drenching with paclobutrazol and foliar sprays of Cycocel and Alar on yield and quality of fruits were studied in nine year old mango trees. Fruit yield was enhanced considerably by paclobutrazol at 2.5 or 5.0 g per tree, but at 10.0 g per tree, it reduced yield. Alar at 3,000 mg T1 slightly enhanced yield, but reduced T.S.S. Higher doses of paclobutrazol reduced fruit size, adversely affected T.S.S. and the sugar/acid ratio, and delayed fruit maturity and ripening. Other physico-chemical characters of fruits were not affected. Soil drenching with paclobutrazol at 2.5 g per tree during November and March in alternate years seems recommendable for regulating tree size and enhancing yield in young bearing mango trees.