Salt tolerance of lemon trees as affected by rootstock

Abstract

A field experiment was conducted for five years to study the response of 6-year old lemon trees cv. Verna on three different rootstock (sour orange, Cleopatra mandarin and macrophylla) to uniform applications of four irrigation waters having C1-concentrations of 4 (control), 11, 26.5 and 42.5 mol m-3, respectively.Fruit yield and the growth in trunk circumference were significantly reduced by increasing salinity in the rootzone, although this effect varied with the rootstock. The threshold values for response were 1.53, 2.08 and 1.02 dS m-1 for sour orange, Cleopatra mandarin and macrophylla respectively. The corresponding yield reduction for each unit increase in salinity above those values was 10.5, 13.7 and 14.2%, respectively. Trees on macrophylla accumulated higher C1-concentrations in the leaves than those from the other two rootstocks. The role of the interstock of sanguina orange on restriction of C1 uptake is discussed.The citrus growing area in Spain is located along the Mediterranean sea, with about 64% of water available having chloride concentrations higher than 10 mol m-3 (Martinez et al. 1987). Citrus response to salinity depends on several factors, such as rootstock-scion combination, irrigation system, soil type and climate, and changing some of these factors with the same irrigation water could produce entirely different results. Thus long-term experiments (Heller et al. 1973;Bingham et al. 1974;Shalhevet et al. 1974;Bielorai et al. 1978; Francois and Clark 1980;Cole 1985;Bielorai et al. 1988) have established that the salt tolerance of grapefruit and orange trees on different rootstocks differs.However, to the author's knowledge there is no published information pertaining to long-term effects of salinity on the fruit yield of lemon trees. Thus the objective of this 5-year field experiment was to study the response of lemon trees cv. Verna budded on three different rootstocks to four water qualities by measuring soil salinity, fruit yield and leaf chloride uptake. Offprint requests to: A. Cerda Materials and methodsThe Experimental Research Farm is located at 38~ 2~ with climatic conditions characterized by the following values averaged for the 1985-1989 period: rainfall 455 mm, air temperature 18~ relative humidity 65% and Class A pan evaporation 1751 mm.The experiment was carried out on a deep stony soil with calcium carbonate content of 550 g kg-i, classified as a Paralithic-mollic-calciorthid with a non-uniform profile having a bulk density and a volumetric water content at a matric potential of -0.03 MPa in the 0-0.5 m layer of 1.36 Mgm -3 and 0.27 m 3 m -3 respectively. The corresponding values in the 0.5-1.20 m layer were 1.41 Mg m-3 and 0.23 m 3 m-3 respectively.Uniform seedlings of sour orange, Cleopatra mandarin and macrophylla rootstocks were transplanted from a nursery to the experimental site in June 1976. After two years, macrophylla seedlings were budded with Verna lemon scions, whereas sour orange and Cleopatra mandarin were budded with sanguina orange scions (frost nucellar sel...

Contributions of arbuscular mycorrhizal fungi to growth, photosynthesis, root morphology and ionic balance of citrus seedlings under salt stress

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Chemical, Sensory, and Consumer Evaluations of ‘DaisySL’ Mandarins Grafted onto Three Different Rootstocks

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Assessment of salinity status in intensively cultivated soils under semiarid climate, Murcia, SE Spain

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