Relationships between nutrient composition of flowers and fruit quality in orange trees grown in calcareous soil

M Pestana,P Beja,P J Correia,A De Varennes,E A Faria

doi:10.1093/treephys/25.6.761

Abstract

To determine if flower nutrient composition can be used to predict fruit quality, a field experiment was conducted over three seasons (1996-1999) in a commercial orange orchard (Citrus sinensis (L.) Osbeck cv. 'Valencia Late', budded on Troyer citrange rootstock) established on a calcareous soil in southern Portugal. Flowers were collected from 20 trees during full bloom in April and their nutrient composition determined, and fruits were harvested the following March and their quality evaluated. Patterns of covariation in flower nutrient concentrations and in fruit quality variables were evaluated by principal component analysis. Regression models relating fruit quality variables to flower nutrient composition were developed by stepwise selection procedures. The predictive power of the regression models was evaluated with an independent data set. Nutrient composition of flowers at full bloom could be used to predict the fruit quality variables fresh fruit mass and maturation index in the following year. Magnesium, Ca and Zn concentrations measured in flowers were related to fruit fresh mass estimations and N, P, Mg and Fe concentrations were related to fruit maturation index. We also established reference values for the nutrient composition of flowers based on measurements made in trees that produced large (> 76 mm in diameter) fruit.

Highlights

The correction of iron chlorosis in plants grown on calcareous soils is an old problem with no easy solution (Chandra 1966, Démétriadrès et al 1964)
Tagliavini et al (2000) summarized the economical impact of iron chlorosis in kiwi, peach and pear orchards established on calcareous soils in Italy, Spain and Greece, and concluded that yield losses were directly related to the intensity of iron chlorosis
Calcium and Mg were in the ranges 3.0 – 7.2 and 1.7 – 2.3 g kg-1 dry weight (DW), respectively

Summary

Introduction

The correction of iron chlorosis in plants grown on calcareous soils is an old problem with no easy solution (Chandra 1966, Démétriadrès et al 1964). The need to correct iron chlorosis is related to its effects on yield, fruit size and quality, and to decreases in the growers profits. El-Kassas (1984) reported the negative effect of iron chlorosis on gross yield and fruit quality of lime, resulting in smaller fruits, more acidic and with less ascorbic acid. Iron chlorosis can lead to a delay in fruit ripening in orange and peach (Álvarez-Férnandez et al 2003, Pestana 2000, Pestana et al 2001a, Pestana et al 2002, Sanz et al 1997b). The correction of iron chlorosis with sprays containing iron resulted in larger oranges, representing a gain of more than 35% in the gross income of the farmer (Pestana et al 2001a)

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Discussion

Conclusion