Abstract Genetic resistance to Potato Leafroll Virus (PLRV) is polygenic, which hinders the obtainment of resistant cultivars. However, works carried out at the International Potato Center have identified an andigena accession, LOP-868, with high resistance level and low accumulation of PLRV due to the gene of major effect Rladg. We verify the transfer of the Rladg allele to clones of the cross between LOP-868 and UFLA clones, by using the SCAR RGASC850 molecular marker; to evaluate the reaction of these clones to PLRV by inoculating the virus using aphids; and to analyze their agronomic performance of clones. Among the clones inoculated with viruliferous aphids, 49.3% were negative to the serological test, indicating possible resistance. Clones containing the Rladg allele were identified by the RGASC850 molecular marker, which demonstrates the possibility of transferring the Rladg allele of resistance to PLRV from LOP-868 to Solanum tuberosum. Some clones that presented the Rladg allele are also promising for agronomic performance.

Resumo: O objetivo deste trabalho foi avaliar a relação do tempo para o início da tuberização e da duração do ciclo vegetativo com a tolerância ao calor em batata. Grupos de clones com diferentes tempos para o início de tuberização e durações do ciclo vegetativo foram definidos e avaliados em dois ambientes, e seus índices morfofisiológicos foram estimados em condições de estresse de calor. A amplitude para o início da tuberização foi de 31,8 dias e para a duração do ciclo vegetativo de 30,3 dias. Os grupos de clones formados apresentaram os seguintes parâmetros: tuberização precoce e ciclo vegetativo curto, tuberização precoce e ciclo longo (PL), tuberização tardia e ciclo curto e tuberização tardia e ciclo longo. Em condições de estresse de calor, a produção de tubérculos graúdos do grupo PL apresentou média superior à dos demais grupos. Seis clones (IRF 10-24, IRF 7-61, IRF 2-71, IRF 2-14, IRF 6-104 e IRF 10-44) e três testemunhas ('Markies', CBM 16-16 e CBM 9-10) foram considerados tolerantes ao estresse de calor (média diária de 21,2ºC) e responderam favoravelmente ao ambiente com temperaturas amenas (média diária de 19,0ºC). A partição de matéria seca para os tubérculos foi mais rápida nos clones do grupo PL. Os clones de tuberização precoce e ciclo vegetativo longo apresentaram maior tolerância ao calor, com maior produção de tubérculos do que os demais grupos.

Abstract: The objective of this work was to determine the relationship of the time for tuber initiation and of the duration of the vegetative cycle with heat tolerance in potato. Clone groups with different tuber initiation times and duration of the vegetative cycle were defined and evaluated in two environments, and their morphophysiological indices were determined under heat stress conditions. The amplitude for the beginning of tuberization was 31.8 days, and for the duration of vegetative cycle was 30.3 days. The formed groups of clones showed the following parameters: early tuberization and short cycle, early tuberization and long cycle (PL), late tuberization and short cycle, and late tuberization and long cycle. Under heat stress conditions, the production of large tubers of the PL group was higher than that of the other groups. Six clones (IRF 10-24, IRF 7-61, IRF 2-71, IRF 2-14, IRF 6-104, and IRF 10-44) and three checks ('Markies', CBM 16-16, and CBM 9-10) were considered tolerant to heat stress (21.2ºC daily average), and responded favorably to environment at mild temperatures (19.0ºC daily average). Dry matter partitioning to the tubers was faster in the PL clone group. Clones of early tuberization and long vegetative cycle showed higher tolerance to heat stress, with higher tuber production than the other groups.