Synerigistic effect of Na and K on yield and nutrient uptake in Coleus (Coleus praviflorus L)

Abstract

A field experiment was carried out in College of Agriculture, Vellayani during September 2003 to January 2004 to study the “Synergistic effect of Na and K on yield and nutrient uptake in coleus (Coleus parviflorus L.)”. The treatments included were 50 and 100 per cent of the recommended dose of K alone and in combination with 50, 75 and 100 per cent of Na of common salt to equalize the same amount of recommended dose of K. The experiment was conducted in Randomized Block Design. The plant growth characteristics like plant spread, number of functional leaves and LAI showed significant variation due to treatments. The highest values for these parameters were registered by K and Na at 50:50 proportions, showing the synergistic interaction of the two elements at this combination. Leaf water content varied significantly due to treatments. The 50 per cent K plus 75 per cent Na treated plants showed highest value of RLWC. Even though the chlorophyll content did not show significant difference between treatments, it increased with Na application along with 50 per cent K, revealing a role of Na in chlorophyll biosynthesis Tuber yield did not show any significant difference due to treatments. Even then the 50:50 combinations of Na and K treatment gave the highest tuber yield followed by 100 per cent K plus 50 per cent Na treated plants. The yield attributes like number of tubers, weight of tubers and tuber index did not vary significantly. Among the quality attributes, starch content varied significantly due to treatments. The treatment with 100 per cent K plus 75 per cent Na gave the highest value of starch followed by the 50:50 combinations of Na and K. The cooking quality of treatments T3 (100 per cent K alone), T4 (50 per cent K plus 50 per cent Na) and T5 (50 per cent K plus 75 per cent Na) were similar. The shelf life of 100 per cent K plus 100 per cent Na treated tubers were found to be the highest. There was an increase in the content of N, K, Ca and Mg in the plants when Na was also supplied as treatment. Consequently the uptake of nutrients increased with the application of different levels of Na along with 50 per cent K. This shows that Na has a stimulative effect on uptake of nutrients. Application of Na did not affect any soil properties like pH, EC and organic carbon. The available nutrients like N, P, Ca and Mg increased in Na treated plots Yield of tuber was positively and significantly correlated with the dry matter production and uptake of Ca. Yield was positively correlated with the uptake of all nutrients under study. From the above points, it can be concluded that a combination of 50 per cent K and 50 per cent Na is optimum for getting the maximum yield. From the present study it also became evident that the efficiency of nutrient uptake increased at this combination. By adopting this practice, it was seen that the quality of coleus tubers improved and they became nutritionally more rich. This practice was found to be economically more feasible. Considering all these aspects, this fertilizer practice can be recommended to the farmers for getting a higher profit. From this investigation we can clearly establish a synergistic interaction of the two monovalent nutrient ions, K and Na on the growth and yield of coleus.