Search Results
Kiwifruit (Actinidia chinensis Planchon) is an economically important fruit, and its flowering and production are affected by the chill accumulation in winter. In this study, the chilling requirements of nine kiwifruit cultivars with three ploidy levels (diploid, tetraploid, and hexaploid) were analyzed by using the Dynamic Model, Utah Model, and chilling hours (CH) Model. The chilling requirements for vegetative budbreak of these kiwifruit cultivars were 24–55 chill portions (CP), 316–991 chill units (CU), and 222–853 CH, and the chilling requirements for floral emergence were 45–69 CP, 825–1336 CU, and 655–1138 CH. The chilling requirements for vegetative budbreak and floral emergence were significantly lower for diploid than hexaploid cultivars with tetraploid cultivars intermediate. Pearson correlation analysis indicated that ploidy levels were positively correlated with chilling requirement, with the cv of 0.74 and 0.82 for vegetative budbreak and floral emergence chilling requirements, respectively. In conclusion, these results provide some novel insights of kiwifruit varieties of various chilling requirements, which is beneficial for kiwifruit cultivar selection for different climates and environments.
To study the effects of soil nitrogen (N) fertilization on tea growth, quality and yield, a controlled experiment with green tea [Camellia sinensis (L.) O. Ktze] was conducted. Five N fertilization treatments in soil were designed: 0, 0.97, 1.94, 3.88, and 5.82 g/kg/pot, which were subsequently recorded as N0, N1, N2, N3, and N4. The changes to young shoot biomass, total N and carbon (C), Soil and Plant Analyzer Development (SPAD) value, photosynthetic parameters, senescent characteristics, endogenous hormones, and the quality of green tea leaves were investigated. The results showed that with the increase in N fertilization level, the young shoot biomass, total N and C, SPAD value, net photosynthetic rate (P N), transpiration rate (T r), stomatal conductance (g S), superoxide dismutase activity, indoleacetic acid, gibberellin, zeatin (ZT), caffeine, and amino acids increased at first and then decreased, the maximums appeared at 3.88 g/kg/pot; whereas the intercellular CO2 concentration (C i), malondialdehvde contents, abscisic acid (ABA), polyphenol contents, and the ratio of polyphenols (PP) to free amino acid decreased at first and then increased, the minimums appeared at 3.88 g/kg/pot. The immediately significant change in all parameters appeared after 1 month of N treatments. The experiment showed that 3.88 g/kg/pot N fertilization level was the best for growth, quality, and yield of tea, which could provide a theoretical basis for short-term N fertilization management in tea tree.