Additional nitrogen fertilization affects salt tolerance of lemon trees on different rootstocks

• Published in: Scientia horticulturae 2009-07, Vol.121 (3), p.298-305
• Main Authors: Gimeno, V., Syvertsen, J.P., Nieves, M., Simón, I., Martínez, V., García-Sánchez, F.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chloride; chlorides; Citrus limon; fertilizer rates; foliar application; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; ion transport; irrigation water; leaf water potential; Leaf water relations; leaves; lemons; Mineral nutrition; Net gas exchange; nitrogen fertilizers; Nitrogen, phosphorus, potassium fertilizations; osmotic pressure; phytotoxicity; potassium nitrate; rootstocks; saline water; salt stress; salt tolerance; semiarid zones; Sodium; sodium chloride; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Vegetative propagation. Micropropagation; Vegetative propagation. Sowing and planting. Harvesting
• ISSN: 0304-4238; 1879-1018
• DOI: 10.1016/j.scienta.2009.02.019

Irrigation with saline water is one of the major problems in citrus crop in arid and semi-arid regions. Because rootstock and fertilization play an important role in citrus salt tolerance, we investigated the influence of the nitrogen fertilization and rootstock on salt tolerance of 2-year-old potted Fino 49 lemon trees. For that, trees grafted on Citrus macrophylla (M) or Sour orange (SO) rootstocks were watered for 12 weeks with complete nutrient solution containing either 0 mM NaCl (control, C), 50 mM NaCl (S), 50 mM NaCl with an additional 10 mM potassium nitrate (S + N), or 50 mM NaCl with a 1% KNO 3 (S + Nf) foliar spray application. Trees on M were more vigorous than trees on SO and saline treatments reduced leaf growth similarly in trees on both rootstocks. Trees on SO had a lower leaf Cl − and Na + concentration than those on M. Additional soil nitrogen (S + N) decreased leaf Cl − concentration and increased leaf K + concentration in salinized trees on both rootstocks. However, the salinity-induced reduction leaf growth was similar in S + N and S trees. This was due to osmotic effect, beside leaf Cl − and Na + toxicity, played an important role in the growth response of Fino 49 lemon to the salt stress. Additional foliar nitrogen in the S + Nf treatment also reduced leaf Cl − concentration relative to the S treatment but trees from S + Nf treatment had the lowest leaf growth. Net assimilation of CO 2 ( A C O 2 ), stomatal conductance ( g s) and plant transpiration were reduced similarly in all three salt treatments, regardless rootstock. Salinity reduced leaf water and osmotic potential such that leaf turgor was increased. Thus, the salinity-induced A C O 2 reductions were not due to loss of turgor but rather due to high salt ion accumulation in leaves.