Potassium Management for Improving Processing Tomato Yield and Quality in Xinjiang

Two experiments on K application rate and proper time of fertilization and two trials on K nutrient sources were conducted in Changji City of Xinjiang Province using two tomato varieties (HYH-01 and Tunhe-No.8). Plant uptake of K in later stages of crop growth (i.e., after 48 days of transplanting) was mainly transported to the fruit, so sufficient K supply in later stages is important for K nutrition of processing tomato. Application of K at 120 kg K₂O/ha for variety Tunhe-No.8 and 180 kg K₂O/ha for HYH-01 produced more dry matter than other rates. Application of K produced 24 to 37% (HYH-01) and 11 to 24% (Tunhe-No.8) more fruit yield compared with the control without K. The agronomic efficiency (AE) of K was 134 to 402 kg fruit/kg K₂O for HYH-01 and 49 to 238 kg fruit/kg K₂O for Tunhe-No.8 and decreased with the increase in K application rates. The economic benefit of K application over the control without K fertilizer was US$1,634 to 2,505/ha and US$506 to 1,262/ha for HYH-01 and Tunhe-No. 8, respectively. The average of the two tomato varieties indicated that 50% K applied at flowering and 50% K applied at fruiting with a total rate of 120 kg K₂O/ha produced the highest fruit yield and benefit. An application of 120 kg K₂O/ha as KCl resulted in similar or more fruit yield and economic benefit than K₂SO₄ and KNO₃, but the different sources of K had no significant effect on fruit quality indexes.