Abstract:

This study investigated the growth patterns of selected traits during the tuber initiation stage in potato pre-elite seed multiplication, aiming to provide a reference for cultivation and management of potato pre-elite seed. Pre-elite seeds of the potato variety ‘Quanshu No.5’ were used as materials, and plant growth during the tuber initiation stage was continuously observed. The logistic regression equation was applied to fit growth indicators including plant height, stem diameter, aboveground fresh weight, and aboveground dry weight, and growth models were subsequently established. The results showed that the coefficients of determination (R²) for all growth models during the tuber initiation stage exceeded 0.95, indicating a good fit for the plant growth dynamics. Based on the two inflection points in each growth curve, the tuber initiation stage for each indicator was divided into three phases: early growth phase, rapid growth phase, and late growth phase. Plant height, stem diameter, aboveground fresh weight, and aboveground dry weight entered the rapid growth phase at 12, 14.6, 18.3 and 22.2 days after planting, respectively. The linear growth rates during this phase were 1.5 cm/d, 0.2 mm/d, 6.4 g/d, and 0.9 g/d, with corresponding linear growth increments of 34.6 cm, 6.4 mm, 144.3 g, and 17.3 g, respectively. Among the indicators, stem diameter had the longest rapid growth phase (28.3 d), while aboveground dry weight had the shortest one (20.3 d). Plant height showed the earliest occurrence of the maximum growth rate (23.7 d after planting), whereas aboveground dry weight showed the latest (32.1 d after planting). The study concludes that the logistic regression model can accurately simulate plant growth dynamics during the potato tuber initiation stage. The growth patterns of the measured indicators are generally consistent and follow an S-shaped growth curve. It is therefore recommended that targeted management practices be implemented during the rapid growth phase based on the growth patterns of each indicator, so as to maximize growth increments and provide a sufficient nutrient foundation for tuber expansion during the tuber bulking stage.

Key words: potato, pre-elite seed, ‘Quanshu No.5’, tuber initiation stage, growth model, logistic regression, phenological period, fast-growing period