Response of Brassica campestris to potassium nutrition under NaCl salt stress

A short term hydroponics study was conducted to examine the effect of K nutrition (0, 4 and 8 mM K) on growth and ionic concentration of Brassica campestris (Var. Sultan Ray) under various levels (0, 50, 75 and 100 mM) of NaCl salinity. Experiment was carried out in small plastic pots with plastic lids having holes in them. One-week-old two seedlings were transplanted in each hole having four holes per lid of the pots and after the establishment of plants, NaCl salinity was developed in three increments in the respective pots. The crop was allowed to stand for six weeks and data on root and shoot elongation, fresh and dry matter yields were recorded at the time of plant harvest. A considerable reduction in plant height, shoot and root biomass (up to about 49% as compared to non-saline medium) was observed with increasing NaCl salinity while K nutrition significantly improved plant growth, root and shoot fresh biomass under all salinity levels. Overall, a 15% increase in plant growth and 13 and 17%, respectively gain in dry matter yield was observed as compared to control with the application of both K+ levels under 100 mM NaCl. However, a slight improvement in growth of Brassica was noted with higher level of K+ (8 mM) but was statistically non-significant when compared with lower rate (4 mM K+). The same trend was observed in case of dry matter yield. Tissue Na+ concentration in root and shoot increased with increasing NaCl salinity while K+ concentration decreased significantly. Although, the effect of K nutrition on Ca2+ and Mg2+ concentration in plant tissues was statistically non-significant, however, a decreasing trend in accumulation of Ca2+ and Mg2+ was observed with increasing NaCl salinity in the rooting medium.