Response of two citrus genotypes to six boron concentrations: concentration and distribution of nutrients, total absorption, and nutrient use efficiency

Abstract

A greenhouse experiment was performed to study the effects of boron (B) on growth, nutrient concentration and distribution, nutrient use efficiency, and total nutrient absorption of 2 citrus genotypes. The experimental layout was a 6 × 2 factorial, with 6 B concentrations (0.05, 0.25, 0.50, 1.00, 2.00, and 5.00 mg/L) on 2 genotypes: the sour orange (Citrus aurantium L.) and the Swingle citrumelo (C. paradisi Macf. × Poncirus trifoliata L.). The plants were grown for 3 months in a B-free sand : perlite (1 : 1) medium that was irrigated with 6 half-strength Hoagland's nutrient solutions. Increasing B supply in the nutrient solution increased the B concentration linearly in all parts of the plant in the following order: basal leaves > top leaves > bark > root > stems > wood. There was no consistent effect of B supply on the concentration of other fundamental elements (P, K, Ca, Mg, Mn, Zn, Fe). Furthermore, none of the tested B concentrations significantly affected the total plant content and consequently the absorption of any other element. A concentration of 1.00 mg B/L or higher resulted in less B absorption by the Swingle citrumelo than by the sour orange. Furthermore, the Swingle citrumelo has the ability to retain more B in its stems and roots than the sour orange, thus preventing B transport to leaves. Finally, B and Mn use efficiency in both genotypes correlated significantly and negatively with the B supply.

Diagnosis and Remediation of Nutrient Constraints in Citrus

“…The second school believes that leaves taken from behind the fruit (fruiting terminal) are more reliable due to stabilizing effect of fruit (Terblanche and Du Plessis 1992). Nutrients have some preferential ability to accumulate in specific proportion depending on plant parts and type of rootstock; for example, Swingle citrumelo has the ability to retain more B in its stems and roots than the sour orange, thus preventing B transport to leaves (Papadakis et al 2005).…”

Effects of boron toxicity on root and leaf anatomy in two Citrus species differing in boron tolerance

“…Citrus belong to evergreen subtropical fruit trees and are sensitive to B-toxicity (Papadakis et al 2003). In China, B-toxicity occurs in Citrus orchards from high level of B in soils and from inappropriate application of B fertilizer, especially under low-rainfall conditions (Sheng et al 2010;Chen et al 2012).…”

“…Whilst of lesser importance than B-deficiency, B-toxicity, which is also an important disorder that affects both yield and quality of crops including Citrus in different regions of the world, often occurs in B-rich soils or in soils exposed to B-rich irrigation waters, fertilizers, sewage sludge, or coal fly ash (Nable et al 1997;Papadakis et al 2003;Cervilla et al 2007;Miwa et al 2007). Among many plant species, the typical visible B-toxic symptom is leaf burn (chlorotic and/or necrotic patches), usually at the margins and tips of older leaves (Nable et al 1997).…”

Effects of exogenous B supply on growth, B accumulation and distribution of two navel orange cultivars

“…Boron deficiency results in leaf senescence, and declines tree vigor rapidly after fruit setting, affecting fruit yield and quality in the next years (Xiao et al 2007). Although the effects of excess B in citrus plants have been investigated (Papadakis et al 2003(Papadakis et al , 2004a(Papadakis et al , 2004b, to our knowledge, information on citrus responses to B deficiency is lacking. Our previous studies on seasonal changes in fruits and leaves of 'Newhall' and 'Skagg's Bonanza' navel oranges showed that the two cultivars varied in B uptake (Xiao et al 2007;Sheng et al 2007), which, however, could not explain the mechanisms underlying those differences between the two cultivars in the field experiments.…”