ABSTRACT:
This study aimed to determine the thermal sum of the different stages of development of potato plants to better understand its relationship with tuber sprouting. The potato clones SMIJ461-1, SMINIA793101-3 and SMINIA97145-2 and the cultivar Macaca were evaluated in spring and autumn crop seasons in Santa Maria and Julio de Castilhos, RS. Emergence (EM), tuber initiation (TI) and onset of senescence (OS) of the plants were determined and the accumulated thermal sum (aTS) was calculated in each phase. After harvesting, tubers were stored at 20oC for 15 days for curing and then stored at 10 or 20°C to quantify the percentage of sprouted tubers and the number of sprouts per tuber at 0, 30, 60 and 90 days of storage. The experiment was a factorial of four potato clones and two growth conditions, season and storage temperature, in a random design with four replications of 20 tubers. The environmental conditions of Julio de Castilhos in the spring resulted in a greater aTS from EM and TI to OS than those of Santa Maria, meaning that different crop locations and even seasons should be considered for making inferences about tuber sprouting based upon aTS. The management of storage temperature can promote or retard tuber sprouting, but its effect depends on the potato clone. Based upon combined correlation estimations, the aTS between EM-OS or between TI-OS is a good estimator for potato tuber sprouting.
Key words:
Solanum tuberosum L; day-degree; physiological age