Journal of Applied Horticulture. 2000 publ 2001: 2(1): 6-9

Endogenous hormones and phenols of seedling trees of polyembryonic mango cultivars and their role as rootstocks in scion vigour of cv. Alphonso

Murti, G S R; Upreti, K K; Kurien, R M; Reddy, Y T N

Plant Hormones Laboratory, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore 560 089, India.

Changes in the levels of endogenous hormones, abscisic acid (ABA), cytokinins (t-zeatin riboside (t-ZR) and dihydrozeatin riboside (DHZR)) in xylem sap and leaves and indole acetic acid (IAA) and total phenols in the leaves were determined in seven polyembryonic mango cultivars (Bappakai, Chandrakaran, Furukan, Muvandan, Mylepelian, Olour and Vellaikolamban), which are commonly used as rootstocks. Simultaneously morphological characters were recorded on mango cv. Alphonso of similar age raised on these cultivars as rootstocks to examine whether the hormones and phenols produced by these bear any relationship to the growth and development of scion. Also the stem anatomical features of the shoots of current and previous year growth were studied in Alphonso grafted on two rootstocks imparting contrasting effects on shoot vigour. The morphological attributes such as tree girth and tree volume of Alphonso were generally higher on rootstocks Muvandan, Bappakai and Olour and least on Vellaikolamban followed by Kurukan and Chandrakaran/Mylepelian. The ratio of radial width of phloem to xylem tissue was higher in the shoots of current year growth of Alphonso raised on dwarfing rootstock, Vellaikolamban, than the vigour imparting Olour. Xylem sap yield was higher in Mylepelian, Muvandan, Olour and Chandrakaran and least in Vellaikolamban. Lower levels of ABA and higher levels of cytokinins, t-ZR and DHZR, in the sap and leaves, and IAA in leaves were evident in the seedling trees of Muvandan and Olour. The trends were opposite with respect to these hormones in Vellaikolamban, Kurukan and Bappakai. Leaf phenol content in different cultivars showed similar trends as of ABA. The cultivars that impeded the tree vigour of Alphonso when used as rootstocks yielded lower sap volume and had higher levels of ABA and phenols and lower concentration of cytokinins and auxin. Screening of the polyembryonic cultivars at the initial stages for ABA or phenols in the leaves is suggested for their selection as rootstocks for vigour regulation.