Growth response and ion distribution of two canola varieties to different potassium to sodium ratios

Abstract

Rapeseed (Brassica napus L.) is a crop relatively tolerant to salt. The effect of different ratios of NaCl/KCl was studied in two cultivars (Hyola308 and Kristina) of Rapeseed in 2002. Canola seedlings were grown in Hoagland’s solutions, which were salinized by different ratios of NaCl/KCl. The treatments or KCl:NaCl ratios were 0:0 (control);10:10; 20:0 (Total Added Salt or TAS=20 mol.m-3), 0:75; 10:65; 20:55(TAS=75 mol.m-3); 0:150; 10:140; 20:130; (TAS=150 mol.m-3) in a randomized complete block design with three replications. Plants were harvested before flowering stage and data were collected for root and shoot characteristics. The results indicated that in both cultivars, the shoot dry weight was decreased with increasing NaCl concentration in nutrient solutions. Increasing the KCl concentration in the nutrient medium significantly (P<0.05) reduced the toxic effects of high concentration of NaCl in K20NaCl130 relative to KCl10NaCl140; KCl0, NaCl150 in Hyola308. Salinity increased Na and Cl and decreased K, Ca and Mg contents of roots. Maximum Na accumulation in root was in Kristina and the minimum K content was observed in Hyola308. These observations showed salinity tolerance in Kristina is associated to a restriction of Na absorption at the root level. Salinity decreased the partitioning coefficients of Na and K. Partitioning coefficient of Cl decreased up to TAS=75mol.m-3and then increased. Kristina accumulated more Cl in the oldest leaves and K content in youngest leaves than Hyola308 cultivars.