Browsing by Subject "Potato"

Late blight, caused by Phytophthora infestans (Mont.) de Bary, is considered the most devastating disease in potato (Solanum tuberosum L.) production worldwide. Control methods involve mostly the use of fungicides, which are costly and are under political pressure for reduction in Europe. Potatoes from the major potato cultivar in Sweden, King Edward, previously stacked with three resistance (R) genes (RB, Rpi-blb2 and Rpi-vnt1.1) were tested in a local Swedish field, with spontaneous P. infestans infection over three seasons to evaluate the effectiveness and stability of the resistance on leaves. In addition, testing of resistance was done in both in leaves and tubers. Field results demonstrated that the 3R stacked into the cultivar King Edward, showed practically full resistance to infections of P. infestans, with no difference to fungicide use. Moreover, the resistance was effective in both leaves and tubers. The results reveal the 3R potatoes offer a functional field resistance, that could, alone, reduce the total use of fungicides in agriculture by several percent in Sweden, in an event of modifications in the EU legislation.

The mission of International Potato Centre (CIP) is to achieve food security for developing countries. Late blight is one of the most serious diseases of potato, and efficient control of the disease is needed to get proper yield. Chemical plant protection and resistant cultivars are the main keys in controlling late blight. CIP improves the food security by breeding late blight resistant genotypes, which are further tested in developing countries. In this research CIP’s breeding population B3 was studied for the inheritance and stability of late blight resistance. Inheritance of resistance was analysed by comparing the level of resistance in two consecutive cycles of recurrent selection (C2 and C3). The stability of resistance was analysed by comparing historical data of population B3 in nine different environments in years 2001–2006. Results showed that the fourth cycle of recombination will improve late blight resistance in the population and the resistance is mainly caused by genetic factors. The research also revealed 78 genotypes that had stable late blight resistance in studied environments. In addition, the study suggests that the population contains some still unidentified R genes. Population B3 has already high late blight resistance, which the fourth cycle of recombination will further improve. In addition, the population contains genotypes with stable and extremely high late blight resistance. Thus, the population serves as a strong material for further late blight resistance breeding and as trial genotypes for tropical highlands. However, the still unidentified R genes should be studied further at molecular level to get best out of the population.