Much of the research to improve the production chain of any particular fruit crop will be highly specific to that fruit crop. Such highly specific research is normally covered by local centers of excellence or the consortia they establish. Nevertheless, we have identified for CIAT, as described below, several research themes directly related to several fruit crops, and are exploring the possibility of developing activities for these issues.

Ripening and Post Harvest Deterioration

Control of ripening and postharvest deterioration is of major concern in the marketing of almost all fruit species. For climacteric fruits, the basic metabolism underlying ripening is essentially the same for all such crops. Likewise, in nonclimacteric crops, many of the processes associated with postharvest deterioration, such as softening and degradation of the cell wall, are also probably common to a wide range of species. Although CIAT should explore new opportunities for controlling ripening and postharvest deterioration, the Center, in common with other IARCs in general, is weak in these areas and, to counterbalance this constraint, we shall establish strategic alliances with agencies such as CIRAD or universities that have expertise in these areas.

Flowering

To produce any fruit, a plant must flower. Synchronization and control of flowering and, hence, of fruiting, are fundamental to all organized fruit production systems. Most knowledge on the underlying principles of controlling flowering is based on research on temperate-climate species. Relatively little research has been done on flower induction and control in tropical species.

At the same time, recent discoveries in plant science indicate that numerous species have similar flowering mechanisms, and that these are under genetic control. A better understanding of flowering processes in tropical species would help develop practical techniques for flowering control in the field.

We have also been developing propagation techniques for lulo (Solanum quitoense) and soursop (Annona muricata), and have observed that some in vitro techniques we used to take buds from mature stems will produce early flowering plants in the field.

Broad-spectrum Diseases and Pests

Certain diseases and pests attack a wide range of different crop species. For example, for fruit crops, only a few species of fruit flies damage the fruits of many species, and complicate importation of many fruits for quarantine reasons. CIAT proposes to explore the possibility of studying fruit flies to develop improved control measures and facilitate export of fresh-fruit products. Preliminary contacts have been made with various Colombian entities. The Animal and Plant Health Inspection Service (APHIS) of the USDA, the International Centre of Insect Physiology and Ecology (ICIPE), and the University of Florida have all shown interest in working on a joint program.

Propagation

Improved propagation techniques for tropical fruits offer multiple opportunities to improve production. Farmers frequently cannot obtain seed or propagules of the varieties they desire, and must use, instead, planting material that is of low physiological and sanitary quality.

Many fruit species are open pollinated and, when farmers sow seeds, the resulting plants highly variable. This is both a problem and an opportunity. While the problem is that farmers are not sure of what they are planting, they have the opportunity of selecting the best trees for planting material. A major constraint to this type of farmer selection is the lack of effective, rapid, clonal propagation of woody material.

In a joint project with Corporación BIOTEC, we used soursop (Annona muricata) as a model plant to develop a system of rapid clonal propagation based on micro-grafts of scion material that was initially selected by a local expert. The micro-grafts were successfully propagated and planted at CIAT, Palmira, and in various commercial plantations. So far, they have performed very well, with prolific fruiting and high production levels.

We envisage scaling up the technique so that farmers, in collaboration with nurseries, can select materials they find particularly attractive for propagating and planting. Such scaling up would be an example of how new technology developed at the laboratory level can help farmers carry out their own selection of improved cultivars or clones.

In another context, work on lulo (Solanum quitoense) regeneration has also opened up the possibility of rapid propagation of clonal lulo for commercial production. Regenerated lulo was planted in preliminary small trials in the Western Cordillera of the Andes at an altitude of about 1800 m. The plants have developed normally and are producing abundant flowers and fruits.