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Phalaenopsis flowers are prone to wilting under ethylene (C2H4) stress. 1-Methylcyclopropene (1-MCP) can protect Phalaenopsis flowers against ethylene injury. In this study, we determined the residual effect of 1-MCP and how it is affected by temperature. The efficacy of multiple applications of 1-MCP was also investigated. The residual effect of 1-MCP was determined by pretreating blooming Phalaenopsis amabilis plants with 0.8 μL·L−1 1-MCP for 8 hours on Day 0 followed by 2 μL·L−1 ethylene fumigation for 12 hours on designated days. Without 1-MCP pretreatment, flowers began to wilt within 2 days after exposure to ethylene. Duration of the residual protection of 1-MCP on P. amabilis was ≈6 to 8 days during summer in Taiwan. Lower temperatures after 1-MCP application prolonged protection times. The full protection times under day/night temperatures of 25/20, 20/15, and 15/13 °C were 4 to 8, 10 to 13, and 13 to 17 days, respectively. Furthermore, multiple applications of 1-MCP extended the duration of 1-MCP protection against ethylene. Three applications increased the residual protection of P. amabilis by 1-MCP to at least 24 days.
Understanding of root growth patterns and architecture of apple (Malus ×domestica Borkh.) trees is very important for commercial apple production. Most commercial apple trees are usually a grafted complex consisting of the scion and the rootstock, each of which is a different genotype. Recently, rootstocks of dwarf tree species have been used extensively to meet the convenience in management; however, this practice appears to negatively impact root development. Using minirhizotrons, we investigated root dynamics, root spatial distribution, and shoot growth in ‘Red Fuji’ scion grown: 1) directly on dwarf and vigorous root stocks and 2) on a dwarf root stock placed in between the non-dwarf scion and non-dwarf rootstock (hereinafter referred to as an interstem). The results showed that: 1) one or two peaks in total root length density (TRLD) were observed in each scion/rootstock combinations every year; 2) the greatest TRLD peaks were always observed in between May and December. The peaks of shoot growth were always asynchronous with that of white root length density; 3) compared with scion/vigorous rootstock combinations, inserting a dwarfing interstem between the scion and vigorous seedling rootstock reduced the TRLD; 4) scion/vigorous rootstock combinations had a relatively deep, widespread and large root system. Scion/dwarfing rootstock combinations had a root system distributed in a small region; and the root systems of scion/dwarfing interstem/vigorous rootstock combinations tended to be intermediate between those of scion/vigorous rootstock and scion/dwarfing rootstock. This implies that the insertion of interstems altered the root architecture by not only the quantity of roots, but also the spatial distribution.