MSc

With a view to standardise the agro-techniques for sweet potato var. Sree Nandini, a field experiment was conducted in the wetlands of the instructional Farm of College of Agriculture, Vellayani. The main objectives of this experiment was to work out the optimum dose and time of application of potassium and depth of planting for the sweet potato var. Sree Nandini. The experiment was laid out in split plot design with four replications. The main plot treatments included 3 levels of potassium (50 kg, 75 kg and 100 kg K2O/ha) and 2 depths of planting 95 cm and 10 cm) while the subplot treatments consisted of the different time of application of potassium (full basal, half basal + half topdressing, 1/3 basal + 2/3 top – dressing and 2/3 basal + 1/3 topdressing). An abstract of the results is given below :
Among the vegetative growth characters, the length of vines was found to be maximum at the highest level of potassium while the number of branches and leaf area of index were not influenced by the levels of potassium. The drymatter production and tuber bulking rate were maximum when potassium was applied at 100 kg K2o/ha. The tuber number, length of tuber, girth of tuber and tuber yield were also maximum at the highest level of potassium. Among the quality attributes, starch content was maximum at the highest level of potassium and sugar content was maximum at the lowest level while the crude protein content was not affected by the different levels of potassium. The uptake of potassium and phosphorus were maximum at 100 kg K2o/ha. The highest available nitrogen and potassium content of the soil was also obtained at this level while available phosphorus content of the soil was not affected.
As regards the time of application of potassium, application of potassium in two equal splits produced the longest vines while the number of branches and LAI were not affected. The parameters like drymatter production, tuber bulking rate, length and girth of tubers, tuber yield, starch content of tubers and uptake of potassium by plants were also maximum in this treatment while the vine yield, crude protein content of tubers and uptake of nitrogen and phosphorus by plants were not influenced by the time of application of potassium.
The depth of planting had no significant influence on most of the parameters investigated like number of branches, LAI, drymatter production, tuber number, tuber yield, vine yield, quality attributes of tubers and uptake of nutrients by plants. However, deeper planting increased the length of vines while the size of tubers and tuber bulking rate decreased with deeper planting.
Thus, it is revealed from the present study that the application of 100 kg K2o/ha in two equal split doses – half as basal and half as topdressing in combination with a planting depth of 5 cm is more profitable for the particular variety under the agro-climatic conditions prevailing in Thiruvananthapuram district.