Objectives Potassium (K) nutrition is closely related with crop quality. Clarify of the effect of K fertilizer application on the quality of different crops would provide the basis for the scientific management of K fertilizer to achieve high crop yield and quality.
Methods The literatures published since 1989 were searched by keywords of “potassium” and “quality” in the China National Knowledge Infrastructure (CNKI). There were total of 92 literatures meeting the requirement of Meta-analysis, and 147 groups of data were obtained.The crops in the literature were grouped to cereal crops, vegetables, fruits, oil crops and fiber crops. Taking no K fertilizer treatments as controls, the Meta-analysis method was used to analyze the effects of K fertilizer application on the common quality index of crops under different dosage and types; and then the comprehensive effects of K fertilizer application on the characteristic quality of different crops were further analyzed.
Results Compared with no K application controls, the application of K fertilizer could ameliorate five common qualities like vitamin C, soluble sugar, soluble solids, protein and starch, with the increase rates of 18.6%, 19.3%, 8.7%, 7.3% and 5.2%, respectively. Compared with the appropriate K fertilizer application rate, the unreasonable K fertilizer application would result in the decrease of quality growth rate; and the improvement effect of K-sulfate on crop quality was better than that of K-chloride on average. For cereal crops, the K fertilizer could reduce the chalkiness (16.7%) and chalkiness rate (12.5%) of rice, increase the wet gluten content (4.2%) and sedimentation value (5.4%) of wheat, increase the amino acid (25.3%) and fat content (5.0%) of corn and the single tuber weight (26.6%) of tubers. K fertilizer could decrease the nitrate content of vegetable crops (23.7%), ameliorate the sugar-acid ratio (20.5%), single fruit weight (11.1%) and hardness (3.3%), and reduce the content of titratable acids (5.5%) of fruits; enhance the oil content (3.7%) of oil crops; increase spinning consistency index (6.2%), fiber length (2.2%), fiber elongation (5.3%), fiber breaking strength (3.3%) and micronaire value (2.6%) of fiber crops.
Conclusions Application of K fertilizers can significantly enhance common and economic qualities of crops, although there are slight differences among aplication dosages and types of potassium fertilizers. The reasonable application of K fertilizer depends on the abundance and deficiency of soil available K content and the K requirement of crops. Further attention still needs to be paid on the requirement of characteristic qualities of crops, and balanced fertilization with other fertilizers should also be considered to achieve high crop yield, high efficiency and high quality.
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