In blackcurrant (Ribes nigrum L.) bud break is linked to rooting. Different treatments to break bud dormancy were applied to evaluate their influence on rooting. One-year-old shoots of cv Wellington were collected from 8 year old field grown bushes. Single bud cuttings, 25-30 mm long, were prepared from the middle region of each shoot. The cuttings were soaked in KNO3 at three different concentrations of 0, 1 and 5% for one hour. The 5% KNO3 treatment gave a more advanced stage of bud development and highest number of roots per cutting (Table 1). A one hour KNO3 soaking period, when compared with two, four and eight hours gave an equal or a more advanced stage of bud development and a greater number of roots. In a comparison experiment between the effect of different nitrate salts (KNO3, Ca(NO3)2, Mg(NO3)2, NH4NO3, NaNO3 and Zn(NO3)2), KNO3 gave results similar to the most advanced bud break and largest number of roots.
Table 1. Effect of soaking single bud cutting of blackcurrants in KNO3 solutions. Assessments were made 40 days after treatment application.