Assessing and modelling water use and the partition of evapotranspiration of irrigated hop ( Humulus Lupulus ), and relations of transpiration with hops yield and alpha-acids

Abstract

This study was conducted during three seasons (2012-2014) in an experimental hop yard at Mabegondo, Galicia, NW Spain. The research aimed at calibrating and validating the soil water balance model SIMD-ualKc for Humulus lupulus L. cv. 'Nugget'. The model computes the soil water balance using the dual K c approach, thus partitioning crop evapotranspiration (ET c) into crop transpiration, ground cover transpiration and soil evaporation. Calibration and validation were performed using TDR soil water content measurements, which produced small root mean square errors (RMSE) ranging from 0.012 to 0.015 cm 3 cm −3. The initial, mid-season and end-season basal crop coefficients (K cb) that allow computing hop transpiration were respectively 0.16, 0.97 and 0.83. The single K c for the same crop growth stages, which refers to transpiration and soil evaporation together, were respectively 0.69, 1.02 and 0.85. SIMDualKc provided to estimate water use by the hop yard and the components of the soil water balance, particularly hop transpiration (T Hop), ground covered transpiration (T cover) and soil evaporation (E s). T Hop represented 92% of actual evapotranspiration (ET c act) during the mid-season, and E s averaged 69% of ET c act during the initial stage. It was observed that T cover was strongly influenced by soil and ground cover management. The impacts of water use and T Hop on hop yield quantity and quality were assessed. A linear regression between hop cone yield and T Hop has been found, with a high coefficient of determination r 2 = 0.92, while the linear regressions of T Hop with alpha and beta-acids had regression coefficients not significantly different from zero. These results denote appropriate irrigation management with absence of stresses that could affect yields or the concentration of bitter acids.

Changes in chemical profile of Cascade hop cones according to the growing area

“…However, in our samples, a correlation between -acids content and temperature is not present (Tables 2 and 4). In other studies, 29,30 an influence of rainfall on -acids content was found, but such data are not confirmed in our study, where no such trend is highlighted (Tables 3 and 4). Although no correlation was found in our study, bitter acids and xanthohumol analysis showed significant differences among Cascade samples, thus confirming the important role of the geographical origin on the production of these compounds, even if the differences are not related to the parameters taken into consideration.…”

Crop Coefficients and Transpiration of a Super Intensive Arbequina Olive Orchard using the Dual Kc Approach and the Kcb Computation with the Fraction of Ground Cover and Height

“…Ground cover conditions affecting soil evaporation may be taken into consideration in the water balance simulations by SIMDualKc and were therefore observed. They refer to both crop residues and active ground cover [34,35,46]. In 2011, a reduced active ground cover was present from early January until May, covering 10% of the ground in the row and 5% in the inter-row.…”

Evapotranspiration Partition and Crop Coefficients of Tifton 85 Bermudagrass as Affected by the Frequency of Cuttings. Application of the FAO56 Dual Kc Model

“…The respective model inputs consisted of: the fraction of mulched soil of 1, low thickness of the mulch, and 3% reduction in E s for each 10% of soil surface covered. In former applications of SIMDualKc to soils with organic mulch or crop residuals [56,57] a larger reduction of E s was considered.…”