The Influence of NaCl on Water Relations and Leaf Gas Exchange for Lane Late Citrus Plants and Different Rootstocks
Eighteen-month-old trees of citrange Carrizo, Cleopatra mandarin and Lane late, the latter grafted on both of the former rootstocks, were irrigated with three NaCl levels in nutrient solution (20, 40 and 60 mmol/L) to determine the effect of the salinity on water relations, leaf gas exchange and the distribution of saline ions. Regardless of the rootstock sensitivity to salinity, and even at low salinity, roots accumulated the highest amounts of Cl- , acting as an effective barrier to uptake of this ion. Leaves of plants on Carrizo rootstock accumulated three-times more Cl～than those of plants on Cleopatra, showing the capacity of the latter for preventing greater accumulation of shoot Cl-. Carrizo rootstock accumulated Na+ mainly in roots, whereas Cleopatra accumulated it in leaves. The Lane late scion induced a higher foliar Na+ accumulation with regard to rootstocks without grafting, showing that amounts of foliar Na + could be modulated by the rootstock and by the scion. After two months of the treatments, salinity had produced a slight decrease of water potential (- 0. 9 MPa for the 60 mmol/L treatment). Plants under these conditions were adjusted osmotically, since the osmotic potential was reduced by Na+ and Cl-accumulation, and consequently the turgor potential was maintained. No differences in water relations were found between Carrizo, Cleopatra or Lane late/Carrizo and Lane late/Cleopatra plants. However, values of the leaf gas exchange parameters were higher on plants on Carrizo rootstock than on Cleopatra. The salinity treatments reduced the values of these parameters in both rootstocks, independent of their ion-exclusion capacity. Although salinity decreased leaf CO2 assimilation, transpiration and stomatal conductance, instantaneous gas exchange efficiency was similar for the saline and control treatments, so mechanisms of stomatal control could have operated, to avoid plant dehydration. Besides, regardless of the rootstock, the leaf gas exchange parameters were correlated negativity with the concentrations of saline ions, mainly the foliar Na+. The plants studied had different behaviour under salinity depending on the rootstock. Carrizo excluded Na+ from the shoot whereas Cleopatra excluded Cl -. The scion Lane late also modulated foliar Na+ levels. Foliar Na+ and Cl- were implicated in the drop of water potential and in maintaining turgor in the osmotic adjustment process. Foliar Na+ and Cl- were also implicated in the stomatal conductance decrease. The photosynthesis reduction by salinity was due to the decrease of stomatal conductance, mechanisms of stomatal control occurring to avoid plant dehydration.
Additional index words. Chloride Sodium Xylem water potential Osmotic potential Turgor Photosynthesis Transpiration Stomatal conductance Lane late Cleopatra mandarin Carrizo citrange
J. M Navarro I. Porras A. G. Gomez-Gomez O. Perez-Tornero P. Romero P. Botia
Departamento Citricultura, IMIDA, C/Mayor s/n La Alberca 30150, Murcia, Spain, josefam
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
734-739
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）