Blackcurrant material from the gooseberry ("Ribes grossularia"), the red currant ("Ribes rubrum") and the flowering currant ("Ribes sanguineum"). The resulting offspring were further back-crossed to "R. nigrum". Cultivars produced include 'Tisel' and 'Tiben' in 2000 and 'Ores', 'Ruben' and 'Tines' in 2005. Further cultivars 'Polares' and 'Tihope' are being tested. Since 1991, New Zealand has become an important centre for research and development, as its temperate climate is particularly suitable for cultivation of the crop. Breeding programmes are concentrating on yield, large fruit size, consistency of cropping and upright habit. In North America, there is a need for this fruit to
Solanum nigrum from cardiac arrhythmias and respiratory failure. Livestock have also been poisoned from nitrate toxicity by grazing the leaves of "S. nigrum". All kinds of animals can be poisoned after ingesting nightshade, including cattle, sheep, poultry, and swine. However, in central Spain, the great bustard ("Otis tarda") may act as a seed disperser of European black nightshade ("Solanum nigrum"). Black nightshade is highly variable, and poisonous plant experts advise to avoid eating the berries unless they are a known edible strain. The toxin levels may also be affected by the plant's growing conditions. The toxins in "S. nigrum" are most concentrated