Cultivation performance and flowering behavior of day-neutral 'Portola' strawberry in solar greenhouse

The floral differentiation of day-neutral strawberry cultivars depends on external temperature and is not sensitive to photoperiod. It provides the farmers in northern China a possibility to plant this type of cultivars in a solar greenhouse in cold winter. In this study, day-neutral Fragaria × ananassa ‘Portola’ was planted in a solar greenhouse to investigate its flowering behavior, phenological period, yield, and fruit quality with short-day F. × ananassa ‘Jingzangxiang’ as control. It was shown that runner plants of ‘Portola’ had initiated floral differentiation in nursery on August 19 and 80% of tested plants had developed pistils, while only 40% of ‘Jingzangxiang’ plants just initiated the differentiation. The lateral buds without inflorescence were dissected on October 24 and later. It was found that more than 70% of ‘Portola’ buds were in stamen or pistil differentiation stage and more than 57% of ‘Jingzangxiang’ were in sepal or petal differentiation stage. However, no significant differences were found in later investigations on December 21 and February 22. As a result, ‘Portola’ presented earlier flowering and fruit maturing than ‘Jingzangxiang’ in winter. Average weight fruit^‑1 of ‘Portola’ was remarkably higher than that of ‘Jingzangxiang’, while average fruit number plant^‑1 of ‘Jingzangxiang’ was higher. There were no significant differences on average yield plant^‑1 between the two cultivars. Compared with ‘Jingzangxiang’, early yield of ‘Portola’ was higher, however, its late yield was lower. It resulted in similar total yields. Regarding to fruit quality, ‘Jingzangxiang’ showed a better taste. Fruit soluble solid contents of ‘Jingzangxiang’ were higher than ‘Portola’ during the whole season, but the differences gradually decreased with temperature becoming higher.