The Establishment Of Rapid Potassium Nutrition Diagnosis Method For Potato Plants With Under-Mulch-Drip Irrigation

Potato is a typical K-favoring crop and has a great demand on potassium. However, potassium deficiency and over use are common phenomenon in potato production in Inner Mongolia. Therefore, it is essential to understand the potassium nutritional characteristics of potato well, based on which to conduct the appropriate nutrition management with optimum rate of potassium. The precise potassium nutrient management relies on the potassium nutrition diagnosis of potato. Currently, the nutrient analysis were based on the digestion of dry tissues, requiring deatructive sampling, long time sample preparing, and special instruments. This means it is of significance to establish instant potassium nutrition diagnosis method of potato plants in field, which would provide a reference for potassium fertilizer application precisely and timely. The main reasults are as follows:1. The tuber yield would not increase any more when the potassium supply amount reach to a certain level, however the potato plants still absorb the element with the supply of potassium. Thus, the luxury potassium absorption exists in potato, which cause variation of potato K requirement unit tuber yield with K supply levels.2. The potassium concentration of 4th leaf of potato is sensitive to soil K supply, therfore it could be used as indicator of potassium nutrition for rapid diagnosis of potato in field.3. The potassium threshold concentration of 4th leaf of photo Kexin-1 in the emergence of 30 days,45 days,60 days and 75 days were 7783 ppm,5753 ppm,4428 ppm and 3205 ppm, respectively, which needs K supplements when the real test value is lower than the corresponding threshold.4. The potassium fertilization recommendation model for potato cultivar Kexin-1 basing on rapid diagnosis was established from the emergence of 30 days to 75 days as:K30= 53.79x [1+(156-Kreal)/156] (DAE 30); K45= 80.68x [1+(255-Kreal)/255] (DAE 45); K60= 80.68x [1+(384-Kreal)/384] (DAE 60); K 75= 44.82x [1+(328-Kreal)/328] (DAE 75), where Kreal is the real potassium uptakes calculated from the 4 petiole of potassium test value.