Potassium - the key nutrient for tea grown in Latosols of south India: Glimpses of seven decades of potassium research

Abstract

Potassium (K) is second key nutrient of tea after nitrogen. The N:K20::2:3 up to fourth year of planting and N:K20::1:1 in the fifth year was found ideal for young tea. In the pruned year, pruning height at 35-40 cm N:K20 :: 1:1.67; 50-60 cm N:K2O:: 1:1.48 and 65-70 cm NiK2O:: 1:1.25 were found optimum. The highest yield under plucking was obtained at N:K2O:: 1:0.83, when N levels varied from 150 to 450 kg/ha. The polyphenols, amino acids and catechins were found higher when N:K2O ratio varied from 1:0.83 to 1:1. The P x K interaction was found positive to maintain the linear response to nitrogen. Synergism was found between Mg and-K2O levels at higher N:K2O levels and antagonism at lower N:K2O levels. Foliar application of two per cent KNO3 was found better than one per cent each of urea and MOP to provide drought resistance and higher yield. The foliar application of potassium schoenite one to two per cent-was found best K foliar source. The application of 45 K2O kg /ha/year controlled the infection of red rust caused by the alga. The N:K2O::1:2.5 reduced the infestation of shot hole borer in the pruned year and increases yield. The broadcasting method of K application was found better than placement method in tea soils of south India. Four to six splits of K2O along with nitrogen was found beneficial to obtain higher productivity. When application of K was withheld, the reduction in yield was ten-twenty per cent in first and second year and progressively declined and led to mortality of bushes. In conclusion. Potassium is very important for tea crop nutrition. Proper ratio of N:K2O should be maintained along with adequate levels of phosphorus and magnesium for sustainable higher productivity of tea in south India.