Abstract
The aim of this research is to find a simple mathematical model due to sum of effective temperatures and rainfalls from second germination after spring pruning till the technological maturity of hop cones, in order to achieve reliable prognosis of alpha-acids content in hop cv. Aurora. After mathematical analyses of experimental data by Eurequa Formulize 0.96 Beta software 17 equations were offered, and after substituting the values of dependent and independent variables in all equations only one equation was chosen with p = 0.034 (p<0.05). This equation is not reliable in extremely drought year if crop evapotranspiration ET0 in July is higher than 4.5, primarily because of negative influence on formation and development of hop glandular trichomes. Considering achieved results it is possible to suggest following general equation for alpha-acids accumulation in hop: y = [(k1 w) − k2 − (k3 w2)/x] ÷ (−10) ↔ ET0 July ≤ 4.5. Where y is alpha acids content in dry matter (%), x = sum of effective temperatures and w = sum of rainfals, both from second germination after spring pruning till technological maturity of hop cones. Coefficients k1, k2 and k3 are determined for cultivar Aurora (53.8, 453 and 1.33, respectively).
Highlights
The alpha-acids are important quality parameter in the hop industry since their production significantly defines the global hop supply statistics (Pavlovic et al 2008)
The biosynthesis of hop secondary metabolites is divided into three biosynthetic pathways A, B and C, and biosynthesis of humulone or alpha-acids is the final step of C pathway (Nagel et al 2008; Wang et al 2008)
Where: y – alpha-acids content in dry matter (%) x – sum of effective temperatures (°C) from second germination after the spring pruning till technological maturity w – sum of total raifalls for the same period
Summary
The alpha-acids are important quality parameter in the hop industry since their production significantly defines the global hop supply statistics (Pavlovic et al 2008). Mozny et al (2009) found a positive impact of rainfall and a negative effect of temperature on alpha-acids accumulation in Czech Saaz hop cultivar, as well as Srečec et al 2008 in Aurora hop cultivar. Generative bodies in the cultivar Aurora begin to develop in the second half of June (week 26), and the plant is in full blooming by the mid July (week 28). These results stays in line with results of Srečec et al (2008) who found significant decrease of alpha-acids accumulation if average daily reference crop evapotranspiration in June is higher or equal to 4.5. Srečec et al (2008) on the basis of results of linear and multiple correlations suggested a following functional equation for accumulation of alpha acids (equation 1)
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