Physiological and anatomical disturbances induced by chloride salts in sensitive and tolerant citrus: beneficial and detrimental effects of cations

Abstract

In citrus, the relative contributions of chloride and cations to growth disturbances induced by salinity are a matter of controversy. Chloride salts (15 mol m -3 CaCl 2 , 30 mol m -3 CaCl and 30 mol m -3 KCl) reduced growth and gas exchange parameters, increased leaf damage and abscission and produced anatomical disarrangements and mineral imbalances in seedlings of sensitive Carrizo citrange (Citrus sinensis x Poncirus trifoliata) and tolerant Cleopatra mandarin (Citrus reshni). In both cultivars, Ca 2+ was more beneficial, and K + more detrimental, for growth than sodium. Photosynthesis and growth disturbances were highly correlated (P ≤ 0·001) with leaf Clbuild-up. In the sensitive genotype, Cl -was also significantly correlated with several leaf anatomical disarrangements, such as increase in succulence. In comparison with sodium, both calcium and potassium increased leaf Clcontent (up to 25 and 69%, respectively). Protective calcium effects were not linked to improvement of photosynthesis, reduction of leaf anatomical disarrangements, or prevention of Cl -and Na + increases. It is proposed that the ameliorative effects of calcium on citrus grown under salinity are mostly related to reduction of leaf abscission. Collectively, the data suggest a cause-effect relationship between Cl -build-up and reduced growth, whereas chloride correlations with declines in photosynthesis or increases in succulence appear to be indirect.

Plant Responses to Salt Stress: Adaptive Mechanisms

“…Romero-Aranda et al [96] studied anatomical disturbances produced by chloride salts (KCl, ClCa2, NaCl) in both sensitive (Carrizo citrange) and tolerant (Cleopatra mandarin) citrus varieties. The salt-induced declines in PN were linked to changes in leaf anatomical properties, such as the increase in leaf thickness and the lower area/volume ratio of mesophyll cells.…”

Physiology of citrus fruiting

“…Salinity adversely influences several aspects of plant vegetative and reproductive growth. Among the physiological processes leading to general reduction of growth, photosynthetic activity, transpiration, stomatal conductance, and even root hydraulic conductivity have been shown to be decreased by salinity (Maas, 1993;Romero-Aranda et al, 1998;Moya et al, 1999;Arbona et al, 2005). Moreover, under these conditions, a wide range of plant nutritional deficiencies is also apparent (Alva and Syvertsen, 1991).…”

“…Furthermore, a clear relationship between leaf Cl -concentration and defoliation has been established (Behboudian et al, 1986;Lloyd et al, 1989;Bañuls and Primo-Millo, 1992;Storey, 1995). Thus, the physiological basis for citrus tolerance to salt stress is mostly related to the ability to limit leaf accumulation of Cl -, a mechanism particularly dependent upon the rootstock (Cooper et al, 1952;Behboudian et al, 1986;Maas, 1993;Bañuls and PrimoMillo, 1995;Romero-Aranda et al, 1998;Levy and Lifshitz, 1999;Storey and Walker, 1999). Additional ions have been reported to improve citrus performance during salt stress.…”

Evaluation of Selected Indian Bread Wheat (Triticum aestivumL.) Genotypes for Morpho-physiological and Biochemical Characterization under Salt Stress Conditions

“…Plants growing under saline condition remain stunted due to reduction in cell elongation and cell division, which are under the control of different auxins, whose synthesis is retarded by the salinity (Loreto et al 2003;Ndayiragije and Lutts 2006). The reduction in biomass increased with the increase exposure of salinity, because of disturbances in physiological and biochemical activities under saline conditions (Craine 2005;Munns et al 2006) that may be due to the reduction in leaf area and number of leaves (Romero-Aranda et al 1998;Dong et al 2007). At heading salinity suppresses reproductive development, spikelet formation and ultimately spikelet number (Mans and Rawson 2004 Tables 2 and 3 were highest in control and non-significant and significantly (p < 0.01) decline under salinity stress when salinity imposed in the form of S1 and S2, respectively.…”