The influence of trichome density on the drying rate of alfalfa forage

Trichomes decrease water loss in some plant species, but their influence on water loss from alfalfa (Medicago sativa L.) forage is unknown. A study was conducted which measured the water loss from field-grown, harvested forage of three erect, glandular-haired alfalfa germplasms, KS161, KS210 and KS224, the eglandular 'Arc' cultivar and the 'Kenland' cultivar of red clover (Trifolium pratense L,). Harvests were taken once in 1995 and 1997, and four rimes in 1996. Plant height, phenological stage, upper and lower stem diameters, leaf:stem ratio and apical stem densities of simple, procumbent glandular and erect glandular trichomes were determined. The drying rate constants of the forage were calculated by a combination of parametric and non-parametric modelling techniques. The harvest x germplasm interaction was significant for all parameters measured. The density of erect glandular hairs varied among entries for all harvests, while the drying rate of harvested forage differed among entries for three of the six harvests. Correlations between densities of erect glandular hairs and drying rate constants were generally low and non-significant, except for one harvest. Erect glandular hairs, at the densities measured in this study, generally did not influence drying rates of alfalfa forage. However, density of total trichomes was significantly and negatively correlated with drying rate For all alfalfa entries. The diameter of the stem had the greatest negative impact on drying rate.