ISHS Acta Horticulturae 629: XXVI International Horticultural Congress: The Future for Medicinal and Aromatic Plants
THE EFFECT OF LIGHT INTENSITY AND NITROGEN FERTILIZATION ON PLANT GROWTH AND LEAF QUALITY OF NGO GAI (ERYNGIUM FOETIDUM L.) IN MASSACHUSETTS |
| Authors: | C.A. Casey, F.X. Mangan, S.J. Herbert, A.V. Barker, A.K. Carter |
| Keywords: | Culantro, culinary herbs, medicinal plants |
| Abstract:
Ngo gai (Eryngium foetidum L.) is a leafy green culinary and medicinal herb currently marketed in Massachusetts as an import. The objective of this research was to elucidate the optimal light intensity and nitrogen fertilization rate for the cultivation of ngo gai in Massachusetts. A field trial was implemented in 2001 to examine the growth of transplants under five light regimes (0, 20, 40, 60, and 80 % shade) using shade cloth to reduce incident light. Within each light intensity three rates of nitrogen fertilizer were supplied (0, 45, and 90 kg N/ha) as NH4NO3 over two applications. Emerging flower stalks were removed on a weekly basis and were weighed and dried. Sixty days after transplanting, the plants were harvested and biomass production, leaf area, and leaf nitrogen contents were assessed. Plants grown at the highest light intensities produced the greatest numbers of flower stalks, and these were heavier than those produced in the shade. The intermediate nitrogen fertilization level resulted in the greatest flower mass, with the highest fertilization level resulting in the lowest flower mass. Leaf tissue nitrogen content increased with increasing nitrogen fertilization. Leaf quality increased with increasing shade due to increasing specific leaf area and moisture content of these plants. Plants grown under increasing shade had decreasing biomass production, fewer leaves, and less overall total leaf area. However, the plants grown under increasing shade partitioned more of their biomass to aboveground vegetative production so that the leaf area ratio increased with increasing shade. The highest mean leaf area value was at 40 % shade. Mean leaf area was also affected by rate of nitrogen fertilization resulting in the highest leaf areas at 90 kg N/ha. Because ngo gai is sold by the bunch rather than by weight, mean leaf area is considered to be the most important parameter to optimize. It was concluded from this research that optimal conditions for ngo gai cultivation in Massachusetts are at 40 % shade with a nitrogen fertilization rate of at least 90 kg N/ha. | |
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