Physiological status of shoot in mango (Mangifera indica L.) bearing healthy and malformed floral buds

Physiological parameters were studied in shoots of mango cv. Amrapali in October (at the time of flower bud differentiation) and during February (at the time of flower bud burst). Two types of shoots, i.e. shoot having simple bud (solitary apical) and shoot having multiple buds (apical and axillary buds with several protuberances at their base) were selected for the study. Different physiological parameters viz., macro- and micro-nutrients, plant hormones, enzymes, total phenols, protein content, total organic carbon and C/N ratio were estimated in bud, stem and leaf of different types of shoots. At the time of flower bud differentiation, maximum quantities of IAA, GA₃, P, Ca and Cu were found in bud, total organic carbon, C/N ratio, total phenols, K, Na, ABA and activities of polyphenol oxidase and IAA oxidase in stem and total proteins, N, Mg, Fe, Mn and Zn in the leaf. The shoot bearing multiple buds contained higher levels of IAA, total phenols, C/N ratio and higher IAA oxidase activity. Lower level of GA₃, ABA, polyphenol oxidase, total protein, N, P, Ca, Mg, Fe, Mn, Cu and Zn than stem of shoot bearing simple bud and the levels of total organic carbon and K were found equal in the stem of both types of shoots. The leaf of shoot bearing multiple buds had higher levels of ABA, IAA oxidase, total phenols, C/N ratio and total organic carbon and lower levels of IAA, GA₃, polyphenol oxidase activity, total proteins, N, P, K, Ca, Mg, Fe, Mn, Cu and Zn than the leaf of shoot bearing simple bud but the level of Na was same in the leaf of both types of shoots. Multiple buds, which later terminated into malformed panicles contained higher levels of ABA, IAA oxidase activity, total phenols, total proteins, N, K and Mg and lesser content of IAA, GA₃, C/N ratio, P, Ca, Fe, Mn, Cu, Zn, Na and polyphenol oxidase activity as compared to simple bud.