[Purpose] Mineral elements are very important to plant growth and development, and the proper supply of mineral elements in soil and the optimum range of mineral elements in plant are necessary to guarantee the optimal yield and quality of fruit trees. The application of NPKCaMg fertilizers to fruit trees is frequently insufficient or excessive, which not only causes environmental degradation, but also reduces yield and quality of fruit. [Methods] In order to assess the effects of different fertilizers on biological-related traits of grape fruit and responses to nutritional elements, grapevine (Merlot) was treated with multi-nutrient fertilization for 4 consecutive growing seasons in 2018–2021 at Penglai, Yantai in China. [Results] The principal component analysis showed that the T11 treatment was the appropriate type and rate of fertilizer for this experiment. A 24.29%-35.20% reduction in fertilizer application with T11 treatment (N3P3K1Ca2Mg4) increased HGW, SN, TSS, SP, SFI, and ST, by 3.28%-12.84%, 3.76%-20.03%, 1.11%-14.95%, 2.16%-23.69%, 11.00%-32.78%, 1.07%-23.35%, respectively, compared to T14 (N4P2K3Ca1Mg4), T16 (N4P4K1Ca3Mg2), T13 (N4P1K4Ca2Mg3) and T15 (N4P3K2Ca4Mg1) treatment. The process of flower and fruiting behavior, the floral organs have a large demand for NPK. The requirement for K and B during the growth and development of the fruit was higher than that of other mineral elements. Excess K in soil enhanced the competitive inhibition of Ca uptake by Merlot. The optimum ranges of mineral element content for PP, PFI, PFD, SP and ST in Merlot were mainly related to the grape varieties and nutritional diagnosis methods. [Conclusions] In conclusion, careful selection of NPKCaMg fertilizer supply to soil and optimum range of mineral elements in plant are important basis for proper growth and development of vine.

Rape is one of the most widely cultivated and highest-yielding fruit crops in the world. However, research on its precise nutrient diagnosis and fertilization theory is severely lacking, significantly restricting the development of the grape industry. In this study, an L₁₆(4⁵) orthogonal experimental design was applied to determine the effects of varying ratios of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) on the fruit quality of ‘87-1’ grape (Vitis vinifera L.) cultivated in a facility, aiming to optimize nutrient application rates and improve fruit quality. Among the treatments T5 (N2P1K2Ca3Mg4), T14 (N4P2K3Ca1Mg4), and T9 (N3P1K3Ca4Mg2), treatment T9 had the most significant effect on single fruit weight, total soluble solids (TSS) content, fruit firmness (FF), and fruit quality index (FQI) and was conducive to the positive accumulation of the above quality indicators. Based on a comprehensive multi-factor analysis of variance, the optimal fertilization combination for achieving a high FQI was N3P1K2Ca1Mg2, corresponding to application rates of 375.0, 0, 168.8, 0, and 70.5 kg·hm⁻² for N, P₂O₅, K₂O, CaO, and MgO, respectively. Furthermore, to establish standards for multivariate compositional nutrient diagnosis (CND) and define the nutrient sufficiency range for ‘87-1’ grape fruit cultivated in a facility, the nutrient concentrations in various plant tissues and the soil and the FQI were measured across 80 treatments over five consecutive years. The nutritional status of the grapes cultivated under these treatments was calculated using the Technique for Order Preference by Similarity to Ideal Solution and the CND method. Based on the optimal nutrient ranges for high FQI sub-populations, a precise fertilization model was developed to facilitate economic fertilizer savings, quality improvement, and standardized grape cultivation in a facility.

Composting is an environment-friendly and sustainable way to transform grape branches (GBs) into a useful product. Different parameters can differently affect fertilizer quality. Here, the compost product nutrient content was evaluated using an L9 orthogonal array (parameters, nitrogen source: chicken manure, sheep manure, urea; stirring temperature: 50, 60, 70 °C; initial pH: 6, 7, 8; conditioning agent: calcium superphosphate, zeolite, and copper sulfate). Among the treatments, the T3 (chicken manure, 70 °C, pH = 8, copper sulfate), T2 (chicken manure, 60 °C, pH = 7, zeolite), and T9 (urea, 70 °C, pH = 7, calcium superphosphate) had high gray relational grades (0.7424, 0.7132, 0.7110, respectively). The nitrogen source type (R = 0.1140) had the greatest influence on the nutrient content of the final product, followed by the stirring temperature (R = 0.1104), the conditioning agent (R = 0.0522), and the initial pH (R = 0.0408). Finally, the best nitrogen source of the grape branch compost was chicken manure, the best stirring temperature was 70 °C, the best initial pH was 7, and the best conditioning agent was zeolite. An experimental verification showed that the weighted correlation degree of the optimal treatment predicted by the orthogonal experiment increased by 3.63%.