Endogenous hormones and phenols in rootstock seedlings of mango cultivars and their relationship with seedling vigour.
Murti G. S. R., Upreti K. K.
Author Affiliation: Plant Hormones Laboratory, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore 560 089, India.
European Journal of Horticultural Science 68 : 2-7
Abstract : The morpho-physiological characters and contents of total phenols and endogenous hormones in the seedlings of 7 polyembryonic mango cultivars ('Muvandan', 'Vellaikolamban', 'Chandrakiran', 'Kurukan', 'Bappakai', 'Mylepelian' and 'Olour') and one monoembryonic cultivar ('Alphonso') raised under pot culture conditions were monitored at 30, 60 and 120 days of growth from transplanting. The seedling vigour of the polyembryonic cultivars 'Muvandan' and 'Bappakai' and of the monoembryonic cultivar 'Alphonso' was high. 'Vellaikolamban' was the least vigorous. The leaf area at 60 days of seedling growth was low in the less vigorous cultivars 'Kurukan' and 'Vellaikolamban' and high in 'Muvandan'. Leaf water potential was less negative in the less vigorous cultivars 'Vellaikolamban', 'Kurukan' and 'Chandrakiran'. The total phenol and ABA contents in the leaves were high in less vigorous cultivars 'Vellaikolamban' and 'Kurukan' at all seedling growth stages. Compared with the other cultivars, the leaves of the vigorous cultivars 'Bappakai' and 'Muvandan' had high cytokinin levels, i.e. t-zeatin riboside and dihydrozeatin zeatin riboside levels at 30, 60 and 120 days, and a high IAA level at 30 and 60 days. Plant height and stem girth were negatively correlated with leaf total phenol and ABA contents. Plant height was positively correlated with leaf water potential and cytokinin (t-zeatin riboside and dihydrozeatin zeatin riboside) content. Thus, a higher level of growth inhibitor, ABA and phenols concurrently with lower levels of growth promoters imparted growth restriction of seedlings. It is suggested that the selection of size-controlling rootstocks at the nursery stage can be made by assessing the leaf water potential, total phenols and/or ABA.