Leaf NPK concentration requisite and chemical fertilizer inputs for high yield and quality of peach production in central Hebei Province

  Objectives  We surveyed the critical leaf NPK concentration of high quality and high yield peach, the required chemical fertilizer inputs, and soil available nutrient content to achieve peach’s target yield and quality in central Hebei Province.

  Methods  We selected 60 small peach orchards in central Hebei Province, and leaf samples were collected at 60 days after the full bloom stage to analyze NPK contents. The surveys were conducted for three consecutive years. The three production objectives (yield, single fruit weight, and soluble solid content (SSC)) were investigated at harvest, and the indexes were divided into four grades. The single factor analysis of variance and boundary line analysis were used to test the relationship between leaf nutrient content, chemical fertilizer input, and soil available nutrient content.

  Results  The observed leaf nutrient content variation gradually decreased with increasing yield and quality of peach, and the contents for the highest grade were moderate. The total N, P, and K boundary values for the three objectives were distributed in typical parabolic shapes. Based on the boundary line equations, the critical ranges of total leaf N, P, and K were 3.33%–4.12%, 0.16%–0.29% , and 1.54%–2.50% for the high-yield target (>45 t/hm²), 3.05%–4.61%, 0.13%–0.35% and 1.45%–2.57% for large single fruit weight (>350 g), 3.30%–4.09%, 0.17%–0.32%, and 1.59%–2.64% for sweetness (SSC>15%), respectively. The comprehensive leaf N, P, and K ranges that meet high yield and quality were 3.33%–4.09%, 0.17%–0.29%, and 1.59%–2.50%, respectively. The critical leaf N, P, and K values had a significant linear boundary relationship with chemical N, P₂O₅ fertilizer input, and soil readily available K content. The inflection points for N and P₂O₅ fertilizer input were 210.2 kg/hm² and 236.3 kg/hm², and 110.2 mg/kg for soil readily available K content. The chemical fertilizers required to ensure leaves appropriate N, P and K nutrient content were 40.2–166.8 kg/hm² for N, 11.3–161.3 kg/hm² for P₂O₅, and 36.3–86.8 mg/kg for soil readily available K, respectively.

  Conclusions  Considering fruit yield, individual fruit weight, and sweetness, the critical leaf N, P, and K at 60 days after the full bloom stage were 3.33%–4.09%, 0.17%–0.29%, and 1.59%–2.50%, respectively. The required fertilizer input to attain critical leaf NPK concentration were 40.2–166.8 kg/hm² for N, 11.3–161.3 kg/hm² for P₂O₅, and 36.3–86.8 mg/kg for soil readily available K content, respectively.