Effects of salt stress on lipid metabolism of leaf membranes of two dwarf cashew / Efeitos do stress salino no metabolismo lipídico das membranas foliares de dois cajus anões

Dwarf cashew is one of the main crops in northeast of Brazil. Dozens of low-income families, being the main source of income for small farmers, sell cashew nut. Two commercial clones produced by EMBRAPA agroindustry gather good productivity, small size and precocity, called CCP76 and clone BRS226. The grafted plants transferred to black polypropylene conical tubes with extratified substrate. After acclimatization, the control plants received 40ml of distilled water per day and the same volume of saline solutions. The objective was to evaluate the effects of 60mM and 120mM of NaCl on the leaf membranes during 30 days in clones CCP76 and BRS226. Photosynthesis showed decrease of 12% and 23% in 60mM and 120mM in CCP76; in BRS226 the reduction was 38% and 5% in 60mM and 120mM. Transpiration showed a reduction of 2% in 60mM and a 1% increase in 120mM in CCP76. BRS226 there was a decrease of 6% and 1%, respectively, in 60mM and 120mM. Sodium contents showed no variation of the treatments in relation to the control in CCP76, whereas in BRS226 there was a 20% increase in relation to the control in 120mM. The potassium contents increased 16% in 60mM in CCP76 but in 120mM there was no difference. In BRS226, there was a 30% increase in both 60mM and 120mM. Chloride contents showed increase in both clones and treatment, being 38% in 60mM and 120mM of CCP76 and 8% in 60mM and 33% in 120mM of BRS226. Soluble carbohydrates increased 10% and 15% in 60mM in CCP76 and BRS226. In 120mM it decreased 2% and 20% in CCP76 and BRS226.  Controls had electrical conductivity lower than the treatments in the clones, but in BRS226 120mM was higher. Total lipids increased 1% and 2% in 60mM and 120mM in CCP76, already in BRS 226 increased 2% and 1% in 60mM and 120mM. Total fatty acids decreased 18:3 31% and 10%, in 60mM and 120mM in CCP76 and of 12% and 36% in 60mM and 120mM in BRS226. Monogalactosildiacilglicerol decreased by 40% in 60mM, increasing 50% in 120mM since Digalactosildiacilglicerol decreased 83% and 34% in 60mM and 120mM in CCP76. Monogalactosildiacilglicerol increased 20% and 83% in 60mM and 120mM, decreasing digalactosildiacilglicerol in 60% and 80% in 60mM and 120mM in BRS226. 16:0 increased in 150% monogalactosylcyglycerol in 60mM decreasing 50% in 120mM Digalactosyldiacylglycerol increased 900% and 100% respectively in 60mM and 120mM in CCP76. 16:0 increased 32% in monogalactosyldiaglycerol in 60mM, unchanged in 120mM. Digalactosyldiacylglycerol increased 10% and 300% in 60mM and 120mM in BRS226. In monogalactosylcyglycerol 18:3 decreased 74% and 94% in 60mM and 120mM in digalactosyldiacilglicerol decreased 70% and 90% in 60mM and 120mM in CCP76. In monogalactosylcyglycerol 18:3 decreased 65% and 90% in 60mM and 120mM in digalactosyldiacilglicerol decreased 58% and 86% in 60mM and 120mM in BRS226. Lipid peroxidation increased 18% in 60mM CCP76, decreasing 18% in 120mM, and decreasing 14% in 60mM increasing 5% in 120mM in BRS226. The results suggest that CCP76 is less susceptible to salinity.