Salinity tolerance of citrus rootstocks: Effects of salt on root and leaf mineral concentrations

Abstract

The effects of three concentrations of sodium chloride (NaC1) on seven citrus rootstocks were studied under greenhouse conditions. Leaf and root mineral concentrations and seedling growth were measured. Sodium chloride was added to the nutrient solution to achieve final osmotic potentials of -0.10, -0.20, and -0.35 MPa. Increasing the concentration of NaC1 in the nutrition solution reduced growth proportionally and altered leaf and root mineral concentrations of all rootstocks. Significant differences in leaf and root mineral concentration among rootstocks were also found under stressed and non-stressed conditions. Salinity caused the greatest growth reduction in Milam lemon and trifoliate orange and the least reduction in sour orange and Cleopatra mandarin. No specific nutrient deficiency was the sole factor reducing growth and causing injury to citrus rootstocks. Sodium chloride sensitivity of citrus rootstocks in terms of leaf burn symptoms and growth reduction could be attributed more to C1 than to Na. Sodium and CI concentrations were greater in the leaves than in the roots, particularly at the medium and high salinity levels. Root C1 was not useful for assessing injury because no differences were found in root C1 concentrations among rootstocks. Increasing salinity level did not affect the level of N and Ca in the roots but did reduce N and Ca levels in the leaves. No relationship in mineral concentration or accumulation seemed to exist between citrus leaves and roots. At the -0.10MPa salinity level, sour orange, rough lemon, and Milam were not able to exclude either Na or C1 from their leaves. Trifoliate orange and its two hybrids (Swingle citrumelo and Carrizo citrange) excluded Na at the lowest salt level used, but were unable to exclude Na at the higher salinity levels. Similarly, Cleopatra mandarin excluded C1 at the lowest salt level, but was not able to exclude C1 at higher salt concentrations. Hence, the ability of citrus rootstocks to exclude Na or C1 breaks down at higher salt concentrations.

Salinity–mineral nutrient relations in horticultural crops

“…In citrus grown under saline conditions, calcium was found to be effective at reducing the transport of both sodium and chloride from roots to leaves, thereby alleviating foliar injury and/or defoliation (Ban Äuls et al, 1991;Zekri, 1993a, b;Zekri and Parsons, 1990;Ban Äuls et al, 1997;Zid and Grignon, 1985;Zekri and Parsons, 1992). Increases in salt tolerance of a variety of horticultural crops have been associated with increases in substrate calcium.…”

Calcium induces salinity tolerance in pistachio rootstocks

“…The results of our study also showed that supplemental Ca reduced leaf Na (table IV). Calcium was found to be effective at reducing the transport of sodium from roots to leaves, thereby alleviating foliar injury in citrus grown under saline conditions [42,43].…”

Differences in Root Growth and Permeability in the Grafted Combinations of Dutch Tomato Cultivars (Starbuck and Maxifort) and Japanese Cultivars (Reiyo, Receive, and Magnet)

“…Grafting is widely established in agriculture and provides practical advantages for vegetable production by increasing resistance to soilborne pathogens [1]- [4], tolerance to low root-zone temperatures [5]- [7], salinity tolerance [8]- [10], and endogenous hormone production [11]- [13]. In particular, increased salinity tolerance improves fruit yield of grafted tomato [8] [14].…”