Potato World vision Organic: working on a good potato Consumers often buy organic products because they taste better. The primeval cucumber, an organic cucumber variety with a firm skin and a crispy bite, is a cucumber with a distinct flavour. And pigs that were allowed to root around also have a distinct flavour. But with organic potatoes, to be really honest, you can’t tell the difference. And that is not so surprising. One of the reasons is Phytophthora, which is a problem in organic cultivation. What do you do if the Dutch consumer prefers a yellowfleshed potato, while the less Phytophthora-sensitive varieties such as the Toluca and the Bionica are slightly paler? And what can you do about taste in bad years, when you have to burn the foliage at an early stage, before the potato has had time to mature? You don’t give up, but get down to work. And that is exactly what the organic sector has done in Bioconnect, a network in which research and information for the organic sector is being organised and implemented. It is two years ago now that we started a project with the researchers of the Louis Bolk Institute and Wageningen University. Ready information for standard and organic farming has been put together. We then determined where know-how was missing or where new developments were needed. The objective: to improve the quality of the organic potato. Two results: in the past year and in this early spring, we have focused on pregermination, explained the differences in germination behaviour in different varieties and tested alternative methods for accelerated harvesting. The earlier the potato, the bigger the chance of a decent yield. And, together with the professional and hobby breeders, we have set up a network for developing new potato varieties for the organic sector. This means varieties that are less susceptible to Phytophthora and also do well when grown in organic conditions. Will this also lead to a better taste? Well, whether regular or organic, I’ll eat with a great deal of pleasure any product grown by professionals who care for man and environment, and that has been handled with every care. Marian Blom Manager knowledge and innovation of Bioconnect www.bioconnect.nl www.biokennis.nl PW-ACTUA Direct tuber testing (DTT) speeds up virus testing in Dutch seed potatoes Extensively validated DTT meets a strong need in the seed potato industry, particularly when early exports are planned. Serological ELISA testing being the standard approach in the Netherlands, post harvest control for potato viruses is an important tool to examine seed potato quality. As virus titres usually are low in seed skins, top eyes of potatoes to be tested are grown in the glasshouse to multiply the virus before testing. The resulting test process will last about 4-5 weeks. Dormancy of the freshly harvested potato samples may severely influence the final amount of plantlets tested. Using smart combinations of fluorescent probes, the Dutch General Inspection Service for agricultural seed and seed potatoes (NAK) has forced a breakthrough in molecular multiplex direct tuber testing (DTT) for viruses directly in potatoes. Pooled heel ends are tested with a multiplex realtime PCR enabling the detection of up to four viruses (potato viruses Y, X, A and leaf roll) in one PCR-reaction. Four to five weeks can be gained with DTT as compared with the classical growing-on ELISA. Besides, pooling of seed potato samples reduces expenses. Because dormancy no longer influences test results, all potatoes from the sample are tested thus enhancing the reliability of the test. Extensively validated DTT meets a strong need in the seed potato industry, particularly when early exports are planned. NAK carries out large-scale routine DTT in a new laboratory, especially designed to work with molecular test methods. Dr. Eric Casteleijn, technical director at the NAK, will share his knowledge about DTT at the international congress on 8 and 9 September during PotatoEurope 2009 in Emmeloord (The Netherlands). He will inform you about the possibilities and benefits about this subject. ● Potato World 2009 • number 2 9 Pagina 8
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