Dinâmica de água no solo e eficiência do uso de água em clones de palma forrageira no semiárido pernambucano.

Abstract

The objective was to compare the soil water dynamics, evapotranspiration and water and nutrients use efficiency of the clones of cactus pear, resistant to Carmine Cochineal, during the production cycle in rainfed conditions in Brazilian semi-arid. For this, it was monitored water content in the soil, meteorological variables and biometric over time, and biomass and nutrients data at the end of the crop cycle. Soil water components were quantified for the experimental treatments (IPA-200205/ ‘IPASertânia’ of the Nopalea sp. genre; IPA-100004/‘Miúda’ of the Nopalea sp. of the genre; and, IPA-200016/ ‘Orelha de Elefante Mexican’, genus Opuntia sp.), using data from a capacitive probe and the soil water physical properties, obtaining by residue the crop real evapotranspiration (ETr) and then the evaporative fraction (EF). With biometrics, they were compared the growth of the clones, in terms of the characteristics of the plant and cladodes. In addition, it was determined the characteristics qualitative characteristics of the clones. Through biomass and nutrient data, precipitation and ETr were determined the indicators: crop water productivity, water economic productivity and nutrient use efficiency. At the end there was realized the comparison of these variables between treatments by analysis of variance and Tukey mean test. Rainfed conditions, water storage in soil varied depending on the rainfall events (P) and water extraction capacity of clones. The accumulated ETr and the other components of the water balance in the soil cultivated with the three cactus pear clones showed no significant differences (P < 0.05), only for a few representative periods of the cycle. The average daily rates were in the order of 2.22 ± 0.20 mm day-1, while the evaporative fraction was 0.47 ± 0.05. The Orelha de Elefante Mexicana was the clone that presented more efficient to the Brazilian semi-arid region, in terms of ETr (11.21 kg MV m-3) and P (10.48 kg MV m-3). The Miúda clone may be classified among the evaluated as the less efficient clone. There were no significant differences in terms of chemical composition of the cladodes, water economic productivity and nutrient use efficiency, with the exception of the use efficiency of the magnesium element on the basis of ETr, which was higher for the Orelha de Elefante Mexicana (11.14 g Mg m-3) and IPA Sertânia (7.74 g Mg m-3), and sodium element based on P, which was higher in clones Orelha de Elefante Mexicana (485.43 mg Na m-3) and Miúda (338,36 g Na m-3).