Seed tubers conditioned to 0, 200 or 400 day-degrees above 4t were grown in land infested with Q. pallida. Plants from 400 day-degree seed emerged earlier, had larger canopies and greater dry weights early in the growing season than plants from 0 day-degree seed. However, physiological ageing reduced peak percentage ground cover and advanced crop senescence so that similar quantities of solar radiation were intercepted over the whole growth period. Overall, total and ware yields were not affected much by seed tuber physiological age. The partially resistant cultivars tested were more tolerant than the non resistant cultivars but tolerance was not usually affected by physiological age of seed tubers. The effects of nematicide treatment, initial Q. pallida population density, cultivar maturity class, cultivar resistance status and planting date on nematode multiplication, plant growth and tolerance of attack by Q. pallida are discussed. Using data from a variable temperature water bath experiment, probability and regression analysis estimated mean basal temperatures for the development of Q. pallida and Q. rostochiensis at 2.5 and S.rCi least variance analysis estimates were 3.5 and 4.rC respectively. Approximately 200 day-degrees above 3.5 and 4.rC were required from the inoculation of JJ2 of Q. pallida and G. rostochiensis to the peak numbers of JJ5 found in potato roots. From a range of chemicals tested for their ability to release antigen from Q. pallida cysts, sodium hypochlorite was found to be the most effective. Released antigen was detected using polyclonal antisera and monoclonal antibodies in an ELISA test. The potential for the development of an ELISA based diagnosis test for PCN using species-specific antibodies is discussed.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The potato plant is highly demanding regarding the presence of phosphorus (P) readily available in soil solution. To achieve high yields of tubers, large applications of phosphate fertilizers are made, which consequently reduce the sustainability of the potato chain and cause possible environmental contamination. Therefore, it is necessary to improve the management of fertilizer use and develop potato clones that have high yield and quality, even in limiting conditions of P. In order to identify efficient clones in P acquisition and use, this study aimed to characterize the physiological aspects of potato clones under different levels of P availability and production systems available. In the first experiment, the Asterix, Atlantic, SMIC 148-A and SMINIA 793101-3 clones from micropropagated plants were grown in soilless system under low and high P level (2.32 and 23.2 mg P L-1) during the spring and autumn seasons of Rio Grande do Sul state. In the P utilization efficiency, we found that the potato clones differ between the spring and autumn season of Rio Grande in soilless culture system with the use of sand as substrate. Furthermore, we also compared the P efficiency of these clones between soilless system and field cultivation under low and high P level (70 and 560 kg P2O5 ha-1) in the spring crop. We observed that each clone responds differently to cultivation systems used as nutritional efficiency to P, and the closed cultivation soilless system with use of sand as substrate overestimates the responses of potato clones in relation to P availability. Nevertheless, we sought to differentiate micropropagated potato plants of plants produced from minitubers as nutritional efficiency to P in closed cultivation soilless system with use of sand as substrate under high and low P level again. The data suggest that the propagative origin of the potato plants interferes, in the biomass ratio between root and shoot, and in the harvest index and P utilization efficiency for all clones. The Asterix, Atlantic and SMIC 148-A clones suffer interference of the type of propagation material in use efficiency and P response, while the SMINIA 793101-3 clone is P efficient in the use of nonresponsive in fresh mass production and tubers total dry mass, regardless of propagativa type of the plants. Furthermore, the clones were also evaluated with plants from tubers when grown in pots with soil as substrate in low and high P level (0.025 and 0.11g kg-1) in a greenhouse, we observed based on the total dry mass, the SMIC 148-A and SMINIA 793101- 3 clones are efficient in the use of P, while Atlantic and SMINIA 793101-3 are responsive to the increase of P. / A planta de batata é altamente exigente quanto à presença de fósforo (P) prontamente disponível na solução do solo. Para atingir altas produções de tubérculos são feitas grandes aplicações de adubos fosfatados, reduzindo assim, a sustentabilidade da cadeia produtiva da batata, além de causar uma possível contaminação ambiental. Portanto, é preciso melhorar a gestão do uso dos fertilizantes e desenvolver clones de batata que tenham alto rendimento e qualidade, mesmo em condições limitantes de P. Este trabalho teve por objetivo caracterizar aspectos fisiológicos de clones de batata submetidos a diferentes níveis de disponibilidade de P e sistemas de produção disponíveis para identificar clones eficientes na aquisição e no uso do P. No primeiro experimento os clones Asterix, Atlantic, SMIC 148-A e SMINIA 793101-3 provenientes de plantas micropropagadas foram cultivados em sistema fechado fora do solo sob baixo e alto nível de P (2,32 e 23,2 mg P L-1) durante a primavera e o outono do Rio Grande do Sul. Verificou-se que os clones de batata diferem quanto à eficiência de utilização do P entre os cultivos de primavera e outono do Rio Grande do Sul em sistema de cultivo sem solo com o uso de areia como substrato. Em outro momento, avaliou-se a eficiência ao P desses clones no cultivo fora do solo e à campo sob baixo e alto nível de P (70 e 560 kg P2O5 ha-1) na safra de primavera. Observou-se que cada clone responde de uma maneira diferente aos sistemas de cultivo utilizados quanto a eficiência nutricional ao P, sendo que o sistema fechado de cultivo fora do solo com o uso de areia como substrato superestima as respostas dos clones de batata em relação à disponibilidade de P. Ainda, buscou-se diferenciar plantas de batata micropropagadas de plantas produzidas a partir de minitubérculos quanto a eficiência nutricional ao P em sistema de cultivo fechado fora do solo com o uso de areia como substrato novamente sob alto e baixo nível de P. Os dados sugerem que a origem propagativa de plantas de batata interfere, tanto na relação de biomassa entre raiz e parte aérea, quanto no índice de colheita e na eficiência de utilização do P para todos os clones. Os clones Asterix, Atlantic e SMIC 148-A sofrem interferência do tipo do material propagativo na eficiência de uso e resposta ao P, enquanto o clone SMINIA 793101-3 é eficiente no uso e não responsivo ao P na produção de massa fresca de tubérculos e massa seca total, independente da origem propagativa das plantas. Os clones de batata também foram avaliados a partir de tubérculos em vasos tendo solo como substrato com baixo e alto nível de P (0,025 e 0,11g kg-1) em casa de vegetação, sendo observado com base na produção de massa seca total, que os clones SMIC 148-A e SMINIA 793101-3 são eficientes no uso de P, enquanto que Atlantic e SMINIA 793101-3 são responsivos ao incremento de P.