Modelagem da evapotranspiração e produção para Alstroemeria x Hybrida irrigada em ambiente protegido

Abstract

Modeling of crop productivity, when inserted in the ornamental sector, is not widespread. There are few specific models for estimating ornamental crop production due to the requirement of calibrated parameters for the models. Such parameters are a condition for the model to estimate production for the local weather conditions. Real production (Pr) is directly linked to weather conditions and energy conversion. Agrometeorological models are used for their low input data requirements and simplicity, since models such as Jensen's (1968) use only relative evapotranspiration (ETr / ETp) as the independent variable. The aim of the present study was to determine the actual yield (𝑃��𝑟��) and actual evapotranspiration (ETr) for Alstroemeria x hybrida according to water deficit percentages (90, 75, 60, 45 and 30% vessel holding capacity - VHC). To estimate 𝑃��𝑟��, we used the Jensen agrometeorological model (1968) and for ETr the water balance method (BH), according to Thorthwaite and Mather (1955). To determine potential yield (𝑃��𝑝��) the Wageningen method (MWA) was used and to estimate potential evapotranspiration (ETp) the relationship of reference evapotranspiration (ETo) with the crop coefficient (𝐾��𝑐��) was necessary. The ETo have being obtained by the Penman method (1948). Penalty factors (𝜆��𝑖��) were determined for water deficits (90, 75, 60, 45 and 30% of VHC). Factors were determined using the multiple regression technique using the multiple least squares (MLS) method, based on logarithmic transformations of mean relative yield terms (𝑃��𝑟��/𝑃��𝑝��) as percent VHC and mean relative evapotranspiration. (ETr/ETP) according to phenological phases. The phenological phases were adapted from Girardi (2016): beginning of growth and development (BGD), full growth and development (FGD) and decline in growth and development (DGD). The values of 0.2067, 0.3197 and -0.1124 were estimated for the penalty factors according to the phenological phases of the culture. The explanatory efficiency led to an R² of 0.922. The highest ETr and ETp values were found in the QCD phase (150 to 330 days after transplantation - DAT) and the lowest values were found for the BGD phase (0 to 150 DAT). For 𝑃��𝑟��the highest values were found in the DGD phases (330 to 420 DAT) and the lowest values for the BGD phase. The accuracy of the estimates of the observed and estimated results by the model was based on the agreement (𝐼��𝑐��), precision (𝐼��𝑝��), performance (𝐼��𝑑��) and mean relative error (ERM) indices. To estimate the ETr, the following results were obtained: 0.859; 0.662 and 0.569 for the 𝐼��𝑐��, 𝐼��𝑝�� and 𝐼��𝑑�� indices. The values obtained in the analyzes classified the model with very good agreement, moderate accuracy and moderately good performance in the estimation of ETr. The results obtained in the estimation of 𝑃��𝑟��were: 0,945; 0.9452 and 0.893, classifying the model with agreement, precision and optimum performance. The proposed model was able to estimate the production and evapotranspiration for Alstroemeria x hybrida.