Evaluating phosphorus nutritional status of potato by instant testing of petiole phosphate concentration

The split application of P can increase the yield and P use efficiency of potato，however, there is currently a lack of a reliable method for determining the timing and rates for the split application of P fertilizers to optimize potato production. In this three-year field experiment, we tested the possibility of establishing a potato plant P diagnosis method with a reflectometer RQflex. Potato petiole Pi content was linearly correlated to plant P contents and was significantly sensitive to soil phosphorus supply, suggesting that petiole P content determined by a RQflex meter is a good indicator of potato plant P status. Moreover, the relationship between relative potato yield and petiole Pi content fits a linear platform equation, suggesting that RQflex meter may be useful for rapidly determining the threshold petiole P level. Our results will help in developing a viable method for recommending P-fertilizer application rates during potato growth to optimize potato tuber yields.