Resumo

ZERMENO GONZALEZ, Alejandro et al. Effect of irrigation system and climate on water use efficiency of pecan trees. Terra Latinoam [online]. 2014, vol.32, n.1, pp.23-33. ISSN 2395-8030.

Pecan (Carya illinoensis K.) is an important fruit tree for Mexico. It is grown in arid regions were water availability is the limiting factor for its production. Therefore, it is necessary to obtain the highest possible water use efficiency, which is a function of the irrigation method and the climate conditions of the region. Thus, the objective of this study was to evaluate the water use efficiency of two pecan orchards, with different methods of irrigation and different climate conditions. The study was done during the summer of 2008 in two pecan orchards in northeastern Mexico. One of them is located in southeastern Coahuila (Mieleras, Municipality of Matamoros) irrigated with a subsurface drip irrigation system. The other in northern Coahuila (Zaragoza) has a sprinkler irrigation system. Water use efficiency of the two orchards was defined as the ratio between moles of CO2 absorbed and moles of water vapor evapotranspired by the tree canopies. The results of this study showed that, although average daily CO2 assimilation rate of the Mieleras orchard (441.68 mmol m-2) was statistically equal to that observed in the Zaragoza orchard (489.04 mmol m-2), the average daily intrinsic water use efficiency (mmol CO2 mol-1 H2O) was higher (P ≤ 0.05) in the Zaragoza orchard (1.82) than that in the Mieleras orchard (1.42). This was due to the climate conditions of Mieleras that caused a higher water vapor pressure deficit and a higher evapotranspiration rate, whose effect on water use efficiency was greater than the effect of the irrigation system used.

Palavras-chave : subsurface drip irrigation; sprinkler irrigation; absorbed CO₂; evapotranspired water vapor.