Effect of postharvest treatments with polyamines on physiological and biochemical attributes of kiwifruit (Actinidia deliciosa). Abstract-Introduction. Kiwifruit is a typical climacteric fruit, which grows profitably well in sub-temperate climatic conditions. The major problem with kiwifruit is that it does not ripen for about a week at room temperature but after this period there is a sudden rise in the respiration rate and fruits remain in edible condition for only a few days, giving it a very short shelf life in ambient conditions. Materials and methods. Kiwifruits were treated with different concentrations of spermine [(0.5, 1.0 and 1.5) mM] and spermidine [(1.0, 1.5 and 2.0) mM] by the immersion method; biochemical and physiological analyses were carried out, then fruit were stored in ambient conditions for 15 days. Results and discussion. Polyamine-treated fruits did not show any amount of ethylene evolution up to the 6th day of storage as compared with those of control, in which it started after the 3rd day of storage. The respiration rate was also the lowest in treated fruit. Similarly, polygalacturonase and lipoxygenase activities rose rapidly in control fruits in comparison with polyamine-treated fruits. Conclusion. The doses of spermine at 1.5 mM and spermidine at 2.0 mM showed the best results in extending the shelf life of kiwifruits when stored in ambient conditions [(22 ± 4)°C, RH: (65 ± 5)%].

Profuse flowering and fruiting create high demand for a limited source of carbohydrates, which affects fruit set and development. These plenty number of flowers and fruits must be reduced to allow the trees to produce fruit that meets market expectations for size, color, and quality. The concept of source-sink relationship and the regulation of carbon partitioning in plants is useful for better understanding of crop physiology and the influence of yield-limiting factors on crop production. This relationship between source leaves and the various sink organs affects fruit production in not only the current season, but also the long term performance due to the perennial nature of fruit trees. Modeling early-season whole-tree carbohydrate supply and demand have greatly improved the understanding of the response of trees to manipulation strategies relating source-sink alliance. Various strategies have been adopted to manipulate sourcesink relationship like flower bud inhibition, flower thinning, fruitlet thinning, defoliation, girdling, pruning, application of hormones and nutrients, etc. Thus, a balance between vegetative and reproductive growth is an important aspect for improvement in yield and quality of fruit crops.

No abstract

No abstract

No abstract