ABSTARCT The physiology of floral induction in mango is still controversial and thus further work is needed for a better understanding of reproductive physiology of this important fruit tree. The objectives of this study were to investigate the role of a gibberellins biosynthesis inhibitor, paclobutrazol on floral induction of biennially bearing mango during off year and to examine the possible correlated hormonal and non-structural carbohydrate changes. Three distinctly biennially bearing mango cultivars were tested for two years under North Sudan climates. Results indicated the advantage of paclobutrazol on inducing flowering of the biennially bearing mango cultivars, Miska, Mahmoudi, and Totocombo during off year. Similar trends of hormonal changes were observed during the floral induction period on the tested cultivars. More-specifically, the levels of cytokinins (zeatin (z) + zeatin riboside (zr) and isopentenyl Adenosine (i-Ado) + isopentenyl Adenine (i-Ade)), and to a less extent the levels of abscisic acid (ABA) generally showed trends of increase during the floral induction period, while those of gibberellins (GA1+3+20) and auxin (IAA) were decreased during the same period. Starch levels in most of the cases were increased by the paclobutrazol treatment. Moreover, sucrose levels were generally increased during the floral induction period. To close, possible roles for some of the tested hormones and nonstructural carbohydrates on mango flowering are probably implicated.

EFFECTS OF PACLOBUTRAZOL (PBZ) ON FLORAL INDUCTION AND ASSOCIATED HORMONAL AND METABOLIC CHANGES OF BIENNIALLY BEARING MANGO (Mangifera indica L.) CULTIVARS DURING OFF YEAR

The plant hormones are extremely important agent in the integration of developmental activities. Environmental factors often exert inductive effects by evoking changes in hormones in metabolism and distribution within the plant. Apart from it, they also regulate expression of intrinsic genetic potential of plants. Control of genetic expression has been demonstrated for the phytohormones at both transcriptional and translational levels. Also, hormones receptors and binding proteins have been identified on membrane surface that are specific for some hormones.The use of growth regulators has become an important component of agro-technical procedures for most of the cultivated plants and especially for fruit plants. So far in fruit crops, excessive fruit drop can be controlled by the exogenous application of plant growth regulators. The auxin and gibberellins are widely used to control the fruit drop and to improve the quality of fruit. Ontogenic development from fruit set to fruit ripening and final reach to customer, several agents are responsible for elimination of some fruits from fruit set to final maturity. In this review, we focus on the major functions of plant growth regulators in fruit production.

https://www.phytojournal.com/archives/2017/vol6issue2/PartF/6-2-70-493.pdf

Effect of plant growth regulators on fruit crops

The effects of leaf applications of potassium nitrate (KNO3), alone and in combination with urea at different concentrations on flowering, fruit set and fruit quality of Tommy Atkins' mango grown in the rift valley of Ethiopia were evaluated. The trees were characterised by erratic flowering, continuous and high intensity of vegetative growth as well as irregular bearing. Uniform trees were selected for a randomised complete block design experiment with three replications and three trees per plot. Spraying was conducted initially on the immature postharvest flushes and then repeated after the flushes had matured and had dark green leaves. Potassium nitrate concentrations especially in combination with urea (5 litre solution of 4% KNO3+0.5 g urea tree−1 and 5 litres of 4% KNO3+I g urea tree−1) produced better results for most of the flowering and yield parameters. There was a non-significant difference for the qualitative parameters between the treated and non-treated trees. The supplementation of nitrogen...

Potassium nitrate and urea sprays affect flowering and yields of 'Tommy Atkins' (Mangifera indica) mango in Ethiopia

Flower induction in longan (Dimocarpus longan L.) following the application of 8 gKClO3 m–2 canopy as soil drench at mature leaf stage was associated with a) increased concentrations of the cytokinins zeatin and zeatinriboside in both the bud meristem and the surrounding leaf primordia around 7 to 10 days before first flowers appeared; b) reduced leaf stomatal conductance, transpiration and net CO2 assimilation; c) a transient increase in leaf ethylene evolution, and d) lower export rates of gibberellins, auxin, abscisic acid, and zeatin and zeatinriboside from leaves. The reduced amount of auxin and gibberellins exported from leaves and typically favouring vegetative growth, in combination with increased levels of cytokinins in buds, known to support floral bud development, might play a key role in flower induction not only in longan, but also for other perennial fruit tree crops.

http://www.pubhort.org/ejhs/2008/file_596531.pdf

Flowering in Longan (Dimocarpus longan L.) Induced by Hormonal Changes Following KClO3 Applications

/pdf/effect-of-cultural-practices-and-selected-chemicals-on-2jzc6nopkk.pdf

S. Subhadrabandhu

Papers

Effect of different intervals of potassium nitrate spraying on flowering and production of mango trees (Mangifera indica L.) cv. Tommy Atkins.

Use of paclobutrazol in mango orchard in Southwest Region, Bahia State, Brazil.