SummaryA field experiment was designed to compare control with tissue culture‐derived plants of rice, and to study the effects of natural selection pressure applied to the first generation (R0) ofin vitroplants on the performance of their progeny. Control‐ and R0in vitroplants of four rice varieties from middle altitude in Burundi, i.e. Facagro 57′, Facagro 76′, ‘Kirundo 3’ and ‘Kirundo 9’, were cultivated at four different altitudes (800, 1380, 1650 and 1900 m). Several parameters concerning tillering capacity, plant height development and seed production were measured. The means for most measured parameters were higher in control plants than in thein vitroplants, while the higher variation coefficients and most extreme values were usually found in thein vitroplants. For each variety, the 20 control plants and 20in vitroplants having the highest production were selected at each altitude of 1380 and 1650 m, and their progenies were cultivated on the same site at 1580 m. Among the plants arising from 1650 m, most maximum values, higher variation coefficients and, in some cases, higher means were found in thein vitroplants. In contrast, among the plants arising from 1380 m, higher means most usually corresponded to control plants, while the tendency for maximum values and variation coefficients were unclear. These results indicate the positive effect of natural selection pressure applied in the first generation to plants rising from tissue culture. They also demonstrate that considerable variation may be generatedin vitro.The interest for plant breeding purpos
展开▼
