Inherent variability in structural and functional traits of xylem among three hop varieties

Abstract

Intervarietal differences in xylem structure could significantly affect water transport as well as vulnerability to cavitations and thus crop yield. Evaluation of crop varieties with respect to the specific traits can be thus helpful in breeding and agricultural practice. In the present study we compared basic anatomical traits (vessel length and diameter) as well as theoretical and measured hydraulic conductivities (K) of xylem in stems of three hop varieties (Agnus, Saaz hop - Osvald's clone 31, Vital). There were no statistically significant intervarietal differences in measured K (overall mean 1.68 × 10-6 m4/MPa/s), the ratio between K and theoretical conductivity (mean = 0.194), as well as vessel diameter and vessel length distributions. The only noticeable difference was in the distribution of vessels with the diameter ≥ 100 μm which differed in Vital compared to Agnus or Osvald's clone 31 (Kruskal-Wallis test, P < 0.001). Our results thus indicate highly conservative nature of xylem basic functional and anatomical characteristics in hop varieties studied.