Soil analysis is used to estimate nutrient availability, but nutrient concentrations are not always related to yield in most fruit plants, including grapevines. Thus, additional multivariate mathematical models, such as the compositional nutrient diagnosis (CND), which takes into account leaves nutrient concentration, and yield, can contribute to estimating critical levels or sufficiency bands of elements, as well as to detect deficiency and/or excess of nutrients. The aim of the present study was to establish CND standards, and the critical level and sufficiency band of nutrients, in the grapevine Vitis vinifera L., grown in a subtropical climate region. Leaves were collected in 81 vineyards in the Campanha Gaúcha do Rio Grande do Sul region, Southern Brazil, and analyzed for macro- and micro-nutrient concentration. The yield of each vineyard was assessed. Grapevine nutritional status was calculated through the CND method. CND-r² indices were effective in establishing the nutritional status of grapevines for macro- and micro-nutrients as sub-optimal, excessive, or balanced. The CND methodology established the critical level and sufficiency bands of nutrients more accurately than the current recommendations for grapevines. Multi-nutrient associations were more effective than the single nutrient determination in defining the threshold of a given nutrient that can reduce grapevine yield.

Critical levels (CL) of available potassium (K) in soils and leaves and maximum technical efficiency (MTE) doses are relevant information to define the best K fertilization strategies. The aim of this study was to determine reference values of K in leaves and soil, using Bayesian analysis, in order to maximize grape yield and must quality of ‘Chardonnay’ and ‘Pinot Noir’ grown in a subtropical climate. The vines were subjected to applications of 0, 20, 40, 60 and 80 kg K₂O ha⁻¹ year⁻¹. The CL and MTE doses of K, in leaves and soils, were determined using Bayesian hierarchical models. The range of probability of the occurrence of CL in leaves was 15.8 to 18.9 g K kg⁻¹ in ‘Chardonnay’ and 16.8 to 19.1 g K kg⁻¹ in ‘Pinot Noir’ at flowering. Moreover, the range was 15.3 to 18.1 g K kg⁻¹ in ‘Chardonnay’ and 16.1 to 18.2 g K kg⁻¹ in ‘Pinot Noir’ at veraison. In the soil, the CL of available K for ‘Chardonnay’ was 27.4 mg K kg⁻¹ and for ‘Pinot Noir’ it was 23.2 mg K kg⁻¹. The increase of K in leaves and soil increased the TSS, while the TTA decreased in both cultivars after sufficiency rate. The MTE was estimated in ‘Pinot Noir’. The proposition of CL and/or MTE doses of K can help increase the efficiency of K fertilization in vineyards.

Nitrogen (N) sources are applied to soils cultivated with peach trees. But, soil cover crops, as Paspalum notatum, a Pampa biome native species, commonly present in orchards, can absorb part of N, decreasing the amount used by peach trees. The study aimed to evaluate N absorption and physiological parameters of young peach trees cultivated in soil with the presence and absence of Paspalum notatum. The experiment was carried out for 180 days in a greenhouse, where N sources were applied to peach trees in the presence or absence of Paspalum notatum. Urea and organic compost were used. Dry matter, tissue N and physiological parameters were evaluated in peach trees. Dry matter and tissue N were evaluated in Paspalum notatum. Nitrogen in soil was evaluated. The N uptake by the peach trees with urea application, on average, was 32% higher than the N uptake by the peach trees in the control treatment or with organic compost, regardless of the presence or absence of Paspalum notatum. Cultivation with Paspalum notatum decreased N uptake by peach trees and, consequently, peach trees photosynthetic pigment content, and stimulated senescence anticipation in about 30 days. However, the total dry matter of peach trees cultivated with Paspalum notatum in any of the treatments applied was not modified. These results may guide new ways of co-cultivating cover crops and young peach trees.

Star fruit is an exotic fruit, originally from the topical regions of Asia, which found in Brazil adequate climatic conditions for its development, making it a promising species for cultivation throughout the country. However, despite the favorable climate, soils in tropical regions are generally acidic and have low natural fertility. In addition, due to the perennial condition of the star fruit tree, its roots remain for several years exploring practically the same soil volume, which requires constant monitoring of soil fertility and the nutritional status of plants. Research results have proven that the star fruit tree is responsive to liming and fertilizer application, with productivity gains and improvements in fruit quality. However, to ensure positive responses and success in agricultural activity, it is necessary that soil acidity correctors and fertilizers are applied in a technical and efficient manner based on the use of well-established agronomic tools, such as soil and leaf analysis. This review aims to gather information from studies, mainly those carried out in Brazil, on the nutritional requirements of star fruit trees, suggesting the best agronomic practices of soil fertility and nutrition of this fruit tree.

Nutrient accumulation during the formation of star fruit (Averrhoa carambola) trees can be affected by the water regime and by the cultivar, but the details are not yet known for this species. The aim of this study was to evaluate the nutrient uptake of two star fruit cultivars in the formation phase under two irrigation regimes. The experiment was developed with a completely randomized design, with subdivided plots, with two irrigation levels (with and without irrigation) as plots, and two star fruit cultivars as subplots ('B-10' and 'Golden Star') and seven collection times from 0 to 720 days after transplanting (DAT) into the field as sub-subplots with six replicates. Nutrient uptake was evaluated in stem and leaves, and it was possible to observe that nutrient uptake and the average accumulation rate followed the dry matter mass accumulation of star fruit trees in formation. Nutrient uptake by shoots at 720 DAT differed for the Golden Star cultivar in the rainfed regime and for the B-10 cultivar in both irrigation regimes. There was no difference and followed the sequence Ca > K > N > Mg > S > P > Mn > Fe > Zn > B > Cu, and for Golden Star cultivar in the irrigated regime, the accumulation sequence was Ca> K> N> Mg> Mn> P> S> Fe> Zn > B> Cu. The highest accumulation occurred in the irrigated regime regardless of cultivar. Golden Star cultivar accumulated, on average, larger amounts of N, P, K, Mg, S, Fe and Mn.