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Effects of fertilizer nitrogen shortly before forcing through flowering on carbon-nitrogen composition and flowering of Phalaenopsis

2019; Elsevier BV; Volume: 252; Linguagem: Inglês

10.1016/j.scienta.2019.02.006

1879-1018

Jen-An Lin, Hadi Susilo, Jia-Yun Lei, Yao‐Chien Alex Chang,

Plant Physiology and Cultivation Studies

Phalaenopsis (Phalaenopsis spp.) is an important orchid crop worldwide. Effect of fertilization on its growth has been much investigated, but studies about how nitrogen (N) fertilization affects flowering have sometimes yielded conflicting results. This study investigated how short-term N application affects the flowering of phalaenopsis, in relation to the size of stored N pool. Two cultivars with differing growth habits: Phalaenopsis Sogo Yukidian 'V3' (large white-flowered hybrid; standard type) and Phalaenopsis Sogo Lotte 'F2510' (miniature purple-flowered hybrid; miniature type) were used in this study. Four N fertilization levels (0, 1.4, 14.3, and 28.6 mM) were applied separately from the last 8 weeks of vegetative stage through the entire reproductive stage, hereby defined as a short-term application relative to longer application periods in other studies. In both cultivars, restriction of N supply (0 and 1.4 mM) resulted in a decrease of N content in roots and shoot during the reproductive stage, meaning that N stored in roots and shoot might have been used for inflorescence development. Compared with normal N fertilization level (14.3 mM), high N fertilization (28.6 mM) delayed spiking in the miniature cultivar by 8.9 d, but did not affect spiking of the standard cultivar. Low (1.4 mM) or no N fertilization caused earlier spiking by 1–2 d in both cultivars, and reduced the flower count of the miniature cultivar by 2 and 3, respectively, while the flower count of the standard cultivar remained unaffected. In conclusion, the effects of short-term N fertilization are related to the size of stored N pool. Standard-type phalaenopsis has significant amount of stored N, therefore its flowering is practically unaffected. On the other hand, the flowering performance of miniature-type phalaenopsis is readily affected, owing to its limited stored N.