The interaction between soil water regime and potassium availability on the growth of tea

Abstract

Tea (Camellia sinensis L.) grown in China often suffers from severe seasonal drought in the summer causing drastic effects on productivity. In a field trial, the effect of potassium (K) fertilization on summer tea yields during 1992–1994 was studied and related to the weather conditions of the respective years. Summer tea yields of 1994 (dry year) increased significantly at K2 (300 kg K2O‐ha‐1) compared to the Kl treatment (150 kg K2O ha‐1). In contrast, only marginal effects were observed by increasing K application from Kl to K2 in the years with adequate water availability (1992 and 1993). During the latter maximum tea yields were already achieved with Kl. In addition, a pot experiment was conducted in order to investigate the interaction between the soil water regime and K availability in the soil on tea biomass production. Soil moisture was maintained at 45, 55, 65, 75, and 85% of the field capacity (FC) and K levels were 0 and 500 mg K2Okg‐1. No tea plant survived at the 45% FC level whereas all tea plants survived at or above 75% FC. The survival rate increased substantially in the K treated tea plants under moderate drought stress conditions (55% and 65% FC). The dry matter production was significantly larger with increasing soil moisture and at the high K status in the soil. This observation was most pronounced under water stress conditions. The study indicates that under moisture stress, increased survival, improved dry matter production and yields of tea plants were due to improved K bioavailability following K application. Furthermore, larger amounts of K are required under moisture stress conditions compared to normal water supply.