Rhizosphere processes of tea (Camellia sinensis) plants under spatial heterogeneity of soil potassium

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Soil potassium (K) spatial heterogeneity was general in tea gardens. Yet, rhizosphere processes of tea plants under soil K spatial heterogeneity is unclear. K heterogeneity was simulated by multi-layer split-root system as follows: both sides had K fertilizer (K+/K+), both sides had no K fertilizer (K0/K0), one side had K fertilizer (K+/K0–K+) and the other side had no K fertilizer (K+/K0–K0). Under K spatial heterogeneity, the differences in rhizosphere processes between the two tea plants (low-K tolerant genotype “1511” and low-K sensitive genotype “1601”) were compared. “1511” could maintain relatively stable fine root proportions under different treatments. For “1511” and “1601”, the strongest soil K activation abilities of root exudates appeared in K+/K0–K0 and K+/K0–K+, respectively. The available K and slowly available K of the rhizosphere soils in K+/K0–K+ was 14% and 8% less than those in K+/K+ for “1511”, but the above form K of the rhizosphere soils in K+/K0–K+ was 8% and 10% higher than those in K+/K+ for “1601”. In conclusion, under the spatial K heterogeneity, low-K tolerant tea plant could achieve high K efficiency mainly through the following ways: (1) maintaining good fine root developments; (2) improving the soil K activation in K+/K0–K0 through the secretion of organic acids; (3) promoting the utilization of soil K in K+/K0–K+. Our findings may contribute to the improvement of tea planting patterns and quality in low K tea gardens, and that to understand the interactions between roots and soil of the low K-tolerant genotype tea plants under the condition of K spatial heterogeneity.