Soil water dynamics and evapotranspiration of forage cactus clones under rainfed conditions

Abstract

-The objective of this work was to evaluate soil water dynamics in areas cultivated with forage cactus clones and to determine how environmental conditions and crop growth affect evapotranspiration. The study was conducted in the municipality of Serra Talhada, in the state of Pernambuco, Brazil. Crop growth was monitored through changes in the cladode area index (CAI) and through the soil cover fraction, calculated at the end of the cycle. Real evapotranspiration (ET) of the three evaluated clones was obtained as the residual term in the soil water balance method. No difference was observed between soil water balance components, even though the evaluated clones were of different genus and had different CAI increments. Accumulated ET was of 1,173 mm during the 499 days of the experiment, resulting in daily average of 2.35 mm. The CAI increases the water consumption of the Orelha de Elefante Mexicana clone. In dry conditions, the water consumption of the Miúda clone responds more slowly to variation in soil water availability. The lower evolution of the CAI of the IPA Sertânia clone, during the rainy season, leads to a higher contribution of the evaporation component in ET. The atmospheric demand controls the ET of clones only when there is higher soil water availability; in this condition, the water consumption of the Miúda clone decreases more rapidly with the increase of atmospheric demand.Index terms: Nopalea, Opuntia, CAM photosynthetic pathway, evapotranspiration. Dinâmica de água no solo e evapotranspiração de clones de palma forrageira sob condições de sequeiro

Growth, water use and efficiency of forage cactus sorghum intercropping under different water depths

“…Australia), previously calibrated for the experimental area, as described by Araújo Primo et al (2015). Readings were taken in relative frequency and automatically converted to water depth at every 0.10 m, until the 0.70 m depth, one layer below the lower limit depth of the control volume (0.60 m).…”

“…Darcy-Buckingham equation was used to calculate Q between the 0.50 and 0.70 m layers, which represented deep drainage (negative sign) or capillary rise (positive sign), according to the equations described by Araújo Primo et al (2015).…”

CARACTERÍSTICAS AGRONÔMICAS DE CAPIM-CORRENTE (Urochloa mosambicensis) ADUBADO COM ESTERCO SUÍNO E SUBMETIDO A DUAS ALTURAS DE CORTE

“…O clima da região é do tipo BSwh' de acordo com a classificação de Köppen, ou seja, semiárido com precipitações pluviais médias anuais em torno de 642 mm, concentradas principalmente nos primeiros quatro meses do ano, temperatura média do ar em torno de 24,8°C e umidade relativa do ar em torno de 62,5% (Silva et al, 2015).…”

Meteorological variables and morphological characteristics influencing the evapotranspiration of forage cactus

“…Despite exhibiting the same photosynthetic mechanism (CAM), they present specificities that differentiate them, as, in water use efficiency and morphological characteristics (Silva et al, 2015b;Silva et al, 2014a).…”

“…Silva et al (2014a) point out that cactus species have cladodes with different dimensions, but may have similar cladode area indices (CAI) (CAI equivalent to leaf area index in C3 and C4 plants), which results in distinct interactions with environment, since it affects the density of stomata and the amount of stored water (Lüttge, 2010). Nevertheless, Silva et al (2015b) report that, under the same condition of water availability (rainfed cultivation), cactus species have similar ET.…”