Effects of Nitrogen Concentration on Growth and Nutrient Uptake of Anthurium andraeanum Lind. Cultivated in Coir under Different Seasonal Conditions

Coir is used around the world as a cultivation medium for plants; its commercial popularity is the result of its availability, low cost, and environmentally friendly characteristics. It is used as a medium in the hydroponic cultivation of Anthurium (Anthurium andraeanum Lind.) in Taiwan and is a new source for cut flower production around the world. Little is known about the nutrient requirements of Anthurium cultivated in coir under fluctuating climatic conditions. The objective of this study was to evaluate the influences of various nitrogen (N) concentrations on the growth and nutrient uptake of Anthurium cultivated in coir under different seasonal conditions. Four levels of N concentration in nutrient solution were used: 79 mg L (NS79 treatment), 105 mg L (NS105 treatment), 158 mg L (NS158 treatment), and 210 mg L (NS210 treatment) with NS105 serving as the control. The effects of N concentration and seasonal fluctuations on Anthurium were measured in dry weight, leaf growth, flower growth, and nutrient uptake at different growth stages during the 2-year study period. The results show that the dry weight, leaf area, and flower number were higher in plants receiving NS105 and NS158 treatments than those receiving NS79 and NS210 treatments. However, the NS158-treated plants produced better quality cut flowers than the NS105-treated plants in the first year of cultivation as indicated by their wider, circular spathe. Retarded growth of NS79-treated Anthurium was the product of insufficient N supply and reduced carbon (C) assimilation. The excess supply of N in the NS210 treatment resulted in small potassium (K) and magnesium (Mg) uptakes, which in turn resulted in poor growth in the second year of cultivation. However, the nutrient supplies in the NS158 and NS210 treatments yielded better Anthurium growth during the initial stage than the NS79or NS105-treated groups. Regardless of plant growth, flower yield, and nutrient uptake, there were significant interactions between N treatments and seasonal fluctuations in subtropical conditions during year-round cultivation. We concluded that the limiting factor in Anthurium growth and yield during the spring and summer is the N supply, whereas climate conditions are the limiting factor during the fall and winter. Anthurium (Anthurium andraeanum Lind.) is one of the important cut flowers in the global tropical cut flower market (Pizano, 2005). Recently it has become a popular cut flower in Taiwan, and its cultivation acreage and yield have increased steadily (Chang et al., 2010; Peng, 2003). Nutrient supply is one of the key factors affecting the growth and yield of Anthurium cut flowers (Chang et al., 2010; Dufour and Guerin, 2005; Higaki et al., 1992; van Herk et al., 1998). The optimal nutrient supply depends on a number of factors including medium composition, species, growing stage, and climate (Cardarelli et al., 2010; Gomez-Lopez et al., 2006; Mengel and Kirkby, 2001). Higaki and Poole (1978) and Higaki et al. (1992) studied fertilization effects on A. andraeanum Lind. ‘Ozaki’ with different media in Hawaii and found that the optimal nutrient supply for Anthurium depended on the medium. The nutrient solution formulae recommended by Dufour and Guerin (2005) and van Herk et al. (1998) for the cultivation of Anthurium were different. Dufour and Guerin (2005) and Higaki et al. (1992) also found that the effects of various nutrient solutions on Anthurium flower yield were different, although the observed difference in flower yield was less than one flower per year (Higaki et al., 1992) or two flowers per year (Dufour and Guerin, 2005). Development and growth of Anthurium were significantly affected by seasonal fluctuations (Klapwijk and van der Spek, 1988; van Herk et al., 1998) and the nutrient requirements were dependent on climatic conditions (Fallovo et al., 2009; Mirdehghan and Rahemi, 2007; Rouphael et al., 2008). However, the interaction between fertilization management and seasonal fluctuations on growth, flower yield, and nutrient uptake of Anthurium during year-round cultivation is not clear. Coir is an important substrate for economical horticultural cultivation and is used around the world as a result of its availability, low cost, and environmentally friendly characteristics (Handreck, 1993; Merrow, 1994; Noguera et al., 2000). Coir is used as a medium in the hydroponic cultivation of Anthurium in Taiwan (Chang et al., 2010) and is a new source for cut flower production around the world. However, no information is available concerning the nutrient requirements of Anthurium cultivated in coir under seasonal fluctuations. The objective of this study was to determine the influences of various N concentrations on the growth and nutrient uptake of Anthurium cultivated in coir under subtropical seasonal fluctuations. Materials and Methods Plant materials and growing conditions. The experiment was conducted at the Floriculture Research Center of the Taiwan Agriculture Research Institute (lat. 23 37# N, long. 120 35# E) in central Taiwan from 6 Oct. 2006 to 8 Oct. 2008. Plants were cultivated in a shadehouse covered with two pieces of shade curtain: a curtain with 70% shading efficiency was placed on top of a curtain with 50% shading efficiency. The shadehouse was also covered with a rain screen consisting of a transparent plastic membrane that was placed on top of the shade curtains. The monthly average air temperature and photosynthetically active radiation (PAR) during the experimental period are shown in Figure 1. Young plantlets of A. andraeanum Lind. ‘Tropical’, 20–30 cm in length and with an average leaf number of 4.1, were used in this study. Before transplanting, 24 randomly selected uniform plantlets were measured for HORTSCIENCE VOL. 47(4) APRIL 2012 515 | SOIL MANAGEMENT, FERTILIZATION, AND IRRIGATION