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 wa s conducted which measured the water loss from field-grown, harvested forag e of three erect, glandular-haired alfalfa germplasms, KS161, KS210 and KS2 24, the eglandular 'Arc' cultivar and the 'Kenland' cultivar of red clover (Trifolium pratense L,). Harvests were taken once in 1995 and 1997, and fou r rimes in 1996. Plant height, phenological stage, upper and lower stem dia meters, leaf:stem ratio and apical stem densities of simple, procumbent gla ndular and erect glandular trichomes were determined. The drying rate const ants of the forage were calculated by a combination of parametric and non-p arametric modelling techniques. The harvest x germplasm interaction was sig nificant for all parameters measured. The density of erect glandular hairs varied among entries for all harvests, while the drying rate of harvested f orage differed among entries for three of the six harvests. Correlations be tween densities of erect glandular hairs and drying rate constants were gen erally low and non-significant, except for one harvest. Erect glandular hai rs, at the densities measured in this study, generally did not influence dr ying rates of alfalfa forage. However, density of total trichomes was signi ficantly and negatively correlated with drying rate For all alfalfa entries . The diameter of the stem had the greatest negative impact on drying rate.