关键词: ‘凤丹’, 氮肥, 叶面喷施时间, 生物量, 养分利用

Abstract:

Objective: The objective of this study is to investigate the influence of nitrogen fertiliser spraying time on the nutrient utilization characteristics of Paeonia ostii 'Fengdan' (oil peony) through foliar application of nitrogen, so as to provide a reference for solving the problems of low nitrogen fertiliser utilization efficiency and high production labour cost in oil peony cultivation in China. Method: The 10-year-old P. ostii 'Fengdan' with uniform growth was used as the research object. The intelligent micro-sprinkler irrigation was applied for the leaf surface spraying every 15 days from the bud stage to the seed harvest stage. The total nitrogen application rate during the growth period was 450 kg·hm^?2, with a concentration of 5 g·L^–1 urea solution selected as the sole nitrogen source. Four nitrogen spraying times were set, 3:00–4:00 (T1), 7:00–8:00 (T2), 14:00–15:00 (T3) and 19:00–20:00 (T4), respectively. The effects of different nitrogen fertilizer spraying time during a day on dry matter accumulation, nitrogen, phosphorus and potassium absorption and utilization of P. ostii 'Fengdan' were investigated during its growth process. Result: 1) Under different nitrogen spraying time treatments, the total biomass of twigs increased gradually with the progression of growth stage, and the biomass accumulation of vegetative organs and reproductive organs was highest in the T3 treatment (P>0.05). 2) As the growth period progresses, the plant dry matter allocation proportion in vegetative organs gradually reduced, while that in reproductive organs gradually increased, reaching the highest at 120 days. Among them, the allocation in reproductive organs was highest in T3 (P>0.05), and the dry matter of reproductive organs in 2022 and 2023 accounted for 15.95%–25.81% and 15.36%–18.92% of the total dry matter at 30 days after anthesis, respectively, and reached 34.78%–45.78% at 120 days. 3) The contents of N, P and K in leaves gradually decreased with the progression of the growth period; the contents of N and P in stems first increased and then decreased, while the K content continued to decrease. N, P and K content in leaves and reproductive organs increased gradually, the accumulation of N in stems changed steadily, the accumulation of P first increased and then decreased, and the accumulation of K increased gradually. There were some differences in the nutrient accumulation in different organs between different treatments and different periods. Conclusion: With the same nitrogen concentration, the nitrogen spraying time can affect the vegetative growth and reproductive growth of P. ostii ‘Fengdan’ at different development stages. Foliar spraying of nitrogen fertilizer using micro-sprinkler irrigation from 14:00 to 15:00 is more conducive to plant twigs biomass accumulation. Plant twigs biomass accumulation, plant N, P and K accumulation, nitrogen harvest index, and nitrogen use efficiency are all the highest at that time.

Key words: Paeonia ostii 'Fengdan', nitrogen, spraying time of foliar, allocation of biomass, nutrient utilization