Additional index words. alternate bearing, flowering, fruit removal, gibberellic acid, Olea europaea, paclobutrazol, seed destruction Abstract. GA3 scaffold injections applied between May and November to nonbearing olive (Olea europea L.) trees inhibited flowering the following year, increased shoot width when applied in May, June, and July, and increased inflorescence length when applied in November and February. Fruit removal and seed destruction were effective in improving the return bloom in 'Manzanillo' olives when done before endocarp sclerification. Depending on-the year, endocarp sclerification takes place 7 to 8 weeks after full bloom (AFB), usually about 1 July. Fruit removal had no effect on flowering when done after this time. Scaffold injection of paclobutrazol applied to bearing trees between May and September did not affect flowering the following year. The results of our research supports the hypothesis that olive flower induction occurs around the time of endocarp sclerification. Chemical names used: gibberellic acid (GA3), (2RS,3RS)-1-(4-chlorophenyl)-4-dimethyl-2-1,2-4-triazol-1-yl) pentan-3-ol(paclobutrazol). Alternate bearing affects many fruit tree species, including olive, and is characterized by a large crop load in the "on" year followed by a small crop in the "off" year. Lack of flower bud formation during the on year is the common characteristic of most alternate-bearing species, including olive (Monselise and Goldschmidt, 1982). The mechanism of alternate bearing is unknown, but environmental conditions and endogenous fac- tors affect flower induction (Bernier, 1988; Monselise and Goldschmidt, 1982). From a practical standpoint, fruit thinning is the best available technique to reduce alternate bearing prob- lems in many species.

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The Time of Floral Induction in the Olive

Plant growth regulators are chemical substances which govern all the factors of development and growth within plants. The application of plant growth regulators to crops modifies hormonal balance and growth leading to increased yield, enhanced crop tolerance against abiotic stress and improved physiological trait of crops. Paclobutrazol (PBZ) [(2RS, 3RS)-1-(4-chlorophenyl)- 4, 4-dimethyl-2-(1H-1, 2, 4-trizol-1-yl)-pentan-3-ol], is one of the members of triazole family having growth regulating property. The growth regulating properties of PBZ are mediated by changes in the levels of important plant hormones including the gibberellins (GAs), abscisic acid (ABA) and cytokinins (CK). PBZ affects the isoprenoid pathway, and alters the levels of plant hormones by inhibiting gibberellin synthesis and increasing cytokinins level and consequent reduction in stem elongation. When gibberellins synthesis is inhibited, more precursors in the terpenoid pathway accumulate and that resulted in the production of abscisic acid. PBZ is more effective when applied to the growing media and application on the growing medium would give longer absorption time and more absorption of active ingredient than foliar spray. The application of PBZ to crops is important in reducing plant height to prevent lodging and in increasing number and weight of fruits per tree, in improving the fruit quality in terms of increases in carbohydrates, TSS, TSS/TA and decreases acidity. It further reduces evapo-transpiration and decreases plant moisture stress by enhancing the relative water content of leaf area and develops resistance in the plants against biotic and abiotic stresses. In addition, it acts as highly active systemic fungicide and used against several economically important fungal diseases. In this review, the current knowledge and possible applications of PBZ, which can be used to improve the growth, yield and quality of crops, have been reviewed and discussed. The role of PBZ to mitigate the harmful effects of environmental stresses in crops is also examined. Moreover, various biochemical and physiological processes leading to improved crop production under the effect of PBZ are discoursed in detail.

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Paclobutrazol as a plant growth regulator

Hormonal changes in response to paclobutrazol induced early flowering in mango cv. Totapuri

SummaryTen mango cultivars of tropical and subtropical origin (Carabao, Kensington, Nam Dok Mai, Alphonso, Dashehari, Florigon, Glenn, Irwin, Haden and Sensation) were grafted onto cv. Kensington seedling rootstock and held at four day/night temperatures for 20 weeks (15/10°C, 20/15°C, 25/20°C and 30/25°C). Vegetative growth increased with increasing temperatures. All grew vegetatively at 25/20°C and 30/25°C. Cultivars which did not grow at 20/15°C were Carabao, Kensington and Dashehari. Cultivars Kensington, Nam Dok Mai, Alphonso, Florigon, Glenn, Irwin, Haden and Sensation produced flower panicles at 15/10°C. The rise in temperature increased the average number of growth flushes (in responsive cultivars) from 0.48 at 15/10°C to 3.21 at 30/25°C, and the number of leaves per growth flush (1.22 at 15/10°C to 13.63 at 30/25°C). Distribution of dry matter from new growth was mostly to the roots at the lowest temperature (95% at 15/10°C) and to the leaves (58%) at 30/25°C. The mean daily temperature for zero ...

Effect of temperature on growth, dry matter production and starch accumulation in ten mango (Mangifera indica L.) cultivars

Macadamia, a native of the subtropical forests of eastern Australia, produces a white, creamy, highly valued kernel. Of the many Macadamia species in the family, Proteaceae, only Macadamia integrifolia the smooth shell macadamia), M. tetraphylla (the rough shell macadamia), and a few of their interspecific hybrids have commercial value. M. integrifolia is more widely grown and is a major orchard crop in Hawaii and Australia. In this review, we discuss cultural practices and physiology pertinent to modem macadamia production; included are botany, ecological requirements, nutrition and fertilization, flowering and fruit set, propagation, cultivars, and pests.

E. Tomer

Papers

Inhibition of flowering in mango by gibberellic acid