The aim of this study was to develop mathematical models to estimate the leaf area of common bean (Phaseolus vulgaris) in irrigated and non-irrigated water regimes from linear dimensions. An experiment was carried out in a completely randomized design with a 3×2 factorial arrangement (three cultivars: Triunfo, Garapiá and FC 104; two water regimes: irrigated and non-irrigated) with 25 replicates each. A total of 523 trifoliates were collected throughout the crop cycle. The length (L, cm) and width (W, cm) of the central leaflet of the trifoliate were measured and their product (LW) (cm²) calculated. Then, the leaf area of these trifoliates was determined by digital photography methods using ImageJ® software, and using leaf discs. The number of samples required to estimate the leaf area of a trifoliate was determined to define which method is the most accurate to be used as the real leaf area in generating equations to estimate the leaf area in common bean. The relationship between area by digital photographs and the dimensions of the central leaflet of the trifoliate (L, W and LW) was fitted by linear, quadratic and power models. Subsequently, the predictive capacity of the equations was assessed by the root mean square error (cm2 trifoliate-1), mean absolute error (cm2 trifoliate-1), index of agreement and Pearson’s correlation coefficient. Sample size varied between cultivars, water regimes and evaluation methods. It is more appropriate to use the leaf area provided by ImageJ® as real for comparison purposes in generating models to estimate leaf area from linear measurements, in common bean. The general equation LA = 1.092L1.945 can be used in the tested regimes without accuracy losses.

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Common beans reduce their development and productivity when facing soil water deficit. Comprehension about growth response under this condition can be a tool for cultivar selection and escape from scarcity periods. Therefore, the objective was to characterize bean growth in different water conditions using logistic and chanter models. Two experiments (crop season= EI and fallow season = EII) were carried out in Santa Maria, RS, Brazil in a bifactorial scheme (cultivars: Triunfo, Garapiá, FC104; water condition: irrigated, not irrigated) in a completely randomized design. Fortnightly evaluations of height, number of nodes, stem diameter, root length, aerial part, roots, and nodules dry matter were carried out. The data were adjusted according to the accumulated thermal sum by the logistic and chanter models. From the results, it is noted that there was a dissimilar performance between water conditions, cultivars, and experiments. The best adjustment occurred for stem diameter, node number, and aerial part dry matter. Between models, the logistic is the most suitable to describe common bean growth.

The State of Rio Grande do Sul (RS) has intense water use for irrigated rice production, generating concerns regarding the quality of this water, which will be returned to the water sources at the end of the harvest. Therefore, this study aimed to evaluate the quality of water from rice fields and yield as a function of drainage time.  The treatments were: T1: drainage from full flowering (R4) according to Counce et al. (2000); T2: 7 days after R4; T3: 14 days after R4; T4: 21 days after R4; T5: 28 days after R4; T6 (control): 35 days after R4. At the moment of drainage the leaf height was quantified and the water samples were then collected, where the pH, electrical conductivity, nitrogen (ammonium and nitrate), phosphorus, potassium and sodium solution in solution were quantified of grain yield. All parameters related to water quality studied are in accordance with CONAMA Resolution 357/2005. The productivity results indicate that it is possible to drain irrigated rice from 14 days after full flowering.

The soybean is an alternative of diversification and financial return to the rice farmer. However, it presents difficulties of cultivation and low yield due to the physical characteristics of the soil. In this scenario, the objective of this work was to verify the influence of soil scarification, the genetic material used and the sowing date. Three soybean cultivars, with yield potential classified as “medium”, “high” and “very high”, were sown in a scarified and non-scarified area, in the dates november 7th and december 10th, year of 2018. The scarification opperation occurred on october 1st. Initial establishment varied according to cultivar, soil mechanism and sowing date. Soil scarification effect was verified up to 100 days after the operation. Within the construction of the yield potential, scarification accounted for 14.4 %, sowing date 12.5 % and genetic material 73.1 % of crop grain yield, in the “high” and “very high” potential materials.