No abstract

In various plant species, polyamines have been implicated in regulating developmental phenomena as well as responses to environmental stimuli. The role of polyamines in regulating developmental phenomena in olive trees, such as flowering, is poorly understood, although seasonal changes and temperature effects on polyamine levels in olive trees have been reported. In this study, levels of free polyamines (putrescine, spermine, and spermidine) in the leaves of trees kept under non-inducing conditions were compared with polyamine levels in trees that were induced to flower under chilling and non-chilling conditions. Putrescine and spermine levels were much higher in leaves kept under inductive chilling conditions compared to control trees kept vegetative, but such increased levels of polyamines did not occur in trees that were induced to flower under non-chilling conditions. These results clearly differentiated between the effects of temperature versus the effect of developmental change on free polyamine levels in olive leaves. The results show that changes in free polyamine levels in leaves have little relevance to flowering in olives. Free polyamine levels within auxiliary buds increased when vegetative buds transformed into flowering buds and then declined when buds developed into flowers. Compared to floral buds, immature and mature fruits contained much smaller amounts of polyamines.

Population density and seed tuber is an important agronomic management practices in the production of potato (Solanum tuberosum L.). However, potato farmers in Ethiopia often use random population density and tuber sizes, which contribute to the low yield of the crop. Thus the objective of this study is to review effect of population density and tuber size on yield components and yield of potato. The result of this review shows that the highest plant height and main stems number was found in wider spacing and in medium to large tuber size. In the same way, the number of tuber per plant, average tuber weight and marketable yield increased when potatoes are planted in medium intra row spacing (60 x 30) and using medium (35 to 45 cm) to large (45 to 55 cm) tuber size. However, total tuber number/ha and unmarketable yield increased in closer spacing and medium (35 to 45 cm) tuber size. Thus according to the review to increase total yield and marketable yield, it is better to use medium plant spacing (60 x 30 cm) and medium-sized tubers (35 to 45 mm).

No abstract