Abstract The present study aimed to compare the use of leaf and flower analysis and to verify the most appropriate organ for the diagnosis of the nutritional status of guava trees. The evaluation was carried out using the CND (Compositional Nutrient Diagnosis) methodology, using yield and nutritional contents of the leaf and flower of ‘Paluma’ guava trees in 48 plots of an irrigated orchard. The contents of flower and leaf nutrients were submitted to variance analysis, by the Tukey test at 5%, and the nutrient sufficiency ranges in organs were calculated, as well as the correlations between multi-nutrient variables and yield. Significant differences between contents of nutrients in flower and leaf, as well as greater variability in the nutritional contents in leaf, were observed. The sufficiency ranges of flower proved to be shorter compared to leaf. The number of correlations between nutrients and yield was higher in the flower. The greater sensitivity of the leaf analysis in expressing interactions between nutrients and yield indicates that this organ can also be used for the nutritional diagnosis of guava trees.

Crop productivity evaluation with models simulations can help in the prediction of harvests and in the understanding of the interactions resulting from the soil-plant-atmosphere continuum. The aim of this study was to calibrate and validate the AquaCrop model for maize crop in the edaphoclimatic conditions of Campos Gerais region, Paraná State, Brazil. The analyses were carried out for maize crop with model input data (climate, crop, soil and soil management) obtained from the ABC Foundation Experimental Station in Castro, Ponta Grossa and Socavão. The climate in the region is humid subtropical, with rainfall evenly distributed. The relief varies from flat to gently undulating. The period analyzed in the calibration and validation process comprised 2011 to 2016 and 2012 to 2016 harvests, respectively. The data used in the calibration of AquaCrop was different from those used in the validation process. Observed and simulated yields were evaluated by simple linear regression analyses, absolute and relative errors, correlation coefficient (r), concordance (d) and performance (c) indexes. The calibration of AquaCrop was satisfactory in the locations studied for maize crop, obtaining absolute errors varying from 6 to 121 kg ha–1. The highest calibration errors occurred in Castro. However, the errors were not enough to reduce the performance in the validation process for this localitie. The model validation resulted in “excellent” performance in all locations evaluated. The AquaCrop can be used to predict the maize yield with acceptable accuracy in the Campos Gerais Region, Paraná State, Brazil.

The quantification of nutrients accumulated and exported by banana bunches provides information on the crop nutritional requirements. Thus, the aim of this work was to determine the nutritional demand of 'Grande Naine' and 'Prata Comum' banana bunches in the region of Vale do Ribeira, state of São Paulo. Bunch sampling was carried out in six harvest seasons, summer, and winter. The results of dry matter production and nutrient accumulation in bunches were submitted to analysis of variance. Relative growth rates (TCR), organogenic net accumulation (TALON), export and order of nutrient accumulation in bunches were estimated. K and N were the nutrients most accumulated and exported by both cultivars. In har-vest period 5 (commercial harvest), more dry matter was produced in the summer and more nutrients were accumulated in the winter. The highest TCR values were observed between periods 2 and 3 in the summer and between 0 and 1 in the winter, but it did not always follow TALON. The results obtained are important to adapt the nutritional management of these cultivars to the study region, especially in relation to the growing season, due to the longer permanence of the bunch on the plant in the winter and greater demand for nutrients until commercial harvest.

The knowledge of the inter-seasonal fluctuations in characteristics of fruit quality and production is important for management of plants, prediction of yield and marketing strategies. This study aims to evaluate how the climatic conditions prevailing in the month of harvest impact bunch mass and variability of the size and color of the banana fruit ‘Nanica’ and ‘Prata’ cultivated under marginal tropical climate. The experiments were carried in Registro, Ribeira Valley region, São Paulo, Brazil, in a completely randomized design with 24 treatments (months of bunch harvest) and ten replications, for each cultivar. Cyclic seasonal fluctuations in production were found in for the two cultivars, with the lowest bunch mass (BM), fruit size consistently recorded between July and February associated with lower global solar radiation (Rad) and temperature (T) of the harvest month, but not precipitation (Ppt). The extension of monthly fluctuations in BM were similar to ‘Prata’ (18.95±3.31 kg) and ‘Nanica’ (29.51±4.69 kg). Independent of the harvest month, there was a trend of greater variability for fruit length (FL) and lower for fruit diameter (FD) between fruits of the different positions in the bunch. The correlations between Rad or T of harvest month with BM, FL, FD and SL were all positive. For both cultivars, the shelf life (SL) was longer for fruits of the last hand. There were also positive correlations between Rad or T with SL. The decrease of peel color characteristics of the ‘Nanica’ fruit was associated with cold fronts from autumn to spring and chilling injury, with higher intensity in the last hand.

Banana farming has an important position in Brazilian agricultural production. This position was earned due to the use of cultivation technologies and adequate fertilization made through recommendations of evaluation of foliar analyzes. The objective of this study was to determine the seasonality of the nutritional status of the diagnostic leaf during the development of banana tree. The experiments took place in the city of Sete Barras / SP, with cultivars such as Grande naine and Prata, on summer and winter. It was evaluated the influence of the collection of the diagnostic leaf in the stations, in six seasons during the development of the banana bunch and it was compared with the standard sampling. The values were submitted to analysis of variance, and when the F was significant, a comparison of means was performed. The sampling stations and the collection stages influence the nutrient behavior in the diagnostic leaf of both varieties, with exceptions for Mg and Mn. The average levels of nutrients during the collection stages showed no difference among the 1st, 2nd, 3rd and 4th (standard). Even for the ‘Prata’ and Grande Naine banana plants cultivated in the Ribeira Valley, there is no significant alteration in the nutrient content of the foliage among the 1st to 4th stages, allowing an increasing of collection for foliar tissue analysis.