Fruit set and growth of 'murcott' mandarin hybrid (citrus reticulata blanco x citrus sinensis l. osbeck) and 'tahiti' lime (citrus latifolia tanaka) with use of bioregulators.

Author(s)

Chryz Melinski Serciloto

• Document type: Master's Dissertation
• Press: Piracicaba. , gráficos, ilustrações, tabelas.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2002-01-23

Examining board members

Paulo Roberto de Camargo e Castro; Luiz Carlos Donadio; Joao Domingos Rodrigues

• Advisor: Paulo Roberto de Camargo e Castro
• Field of knowledge: Agronomical Sciences - Agronomy
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP
• Location: Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; ESALQ-BC t634.31; S482f; 78210

Abstract

Alternate bearing, small fruits and fruit set are problems of some citrus cultivars. This research was performed at 2000/2001, in comercial orchards of 'Murcott' mandarin hybrid (Citrus reticulata Blanco x Citrus sinensis L. Osbeck) and 'Tahiti' lime (Citrus latifolia Tanaka), with 10 and 8 years old, located in Mogi-Mirim and Taquaritinga-SP, respectively. In the first trial, it was evaluated the effects of bioregulators ethylclozate 200 mg.L-1, Phenothiol 10 mg.L-1, Fengib 1 ml.L-1, GA3 20 mg.L-1, 2,4-D 8 mg.L-1 and GA3 20 mg.L-1 + 2,4-D 8 mg.L-1 on the fruit thinning and the fruit size of 'Murcott' mandarin hybrid. The treatments were sprayed on whole trees after total petal fall (fruits with approximately 6 mm of diameter), at a rate of 6 litres per tree. The number of fruits per tree and yield (kg/tree) were not affected by the treatments. GA3 20 mg.L-1 + 2,4-D 8 mg.L-1, GA3 20 mg.L-1 and Fenotiol 10 mg.L-1 increased the final fruit size (3.4%; 3.0% and 3.0%), the final fruit weight (7.8%; 8.8% and 9.5%) and the number of fruits of larger comercial size class. The treatments didn´t affected juice content, total soluble solids, acidity, pH, juice colour and peel colour. The CO2 assimilation, transpiration, stomatal conductance and chlorophyll content were not affected by the treatments. In the second trial, it was evaluated the effects of bioregulators 3,5,6-TPA 15 mg.L-1, 2,4-DP 50 mg.L-1, Phenothiol 20 mg.L-1, ethephon 200 mg.L-1 and ethylclozate 200 mg.L-1 on the fruit thinning and the fruit size of 'Murcott' mandarin hybrid. The treatments were sprayed on whole trees after physiological fruit drop (fruits with approximately 22 mm of diameter), at a rate of 6 litres per tree. 3,5,6-TPA 15 mg.L-1, ethephon 200 mg.L-1 and Phenothiol 20 mg.L-1 increased the final fruit size (7.0%; 6.8% and 4.4%), the final fruit weight (19.1%; 17.3% and 8.7%) and the number of fruits of larger comercial size class. However, 3,5,6-TPA 15 mg.L-1 ethephon 200 mg.L-1 decreased the number of fruits per tree (57.1% e 47.9%) and yield (47.8% e 37.5%), in kg/tree. Phenotiol decreased by 0,4 the total soluble solids. The treatments didn´t affected juice content, acidity, pH, juice colour and peel colour. The CO2 assimilation, transpiration, stomatal conductance and chlorophyll content were not affected by the treatments. In the third trial, it was evaluated the effects of bioregulators Phenothiol 10 mg.L-1; Fengib 1 ml.L-1; Brassinolide 0.015 mg.L-1; GA3 20 mg.L-1; 2,4-D 8 mg.L-1 and GA3 20 mg.L-1 + 2,4-D 8 mg.L-1 on the fruit set of 'Tahiti' lime. The bioregulators didn´t change the vegetative growth. The treatments with GA3 (GA3 20 mg.L-1, Fengib 1 ml.L-1 e GA3 20 mg.L-1 + 2,4-D 8 mg.L-1) increased the fruit set. The best treatment was GA3 20 mg.L-1 + 2,4-D 8 mg.L-1 that promoted 21.3% of fruit set against 5.9% by control. The fruit set was coupled to increases in chlorophyll content and CO2 assimilation by leaves of 'Tahiti' lime. (AU)