Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2003
Publication Date: N/A
Interpretive Summary: In business it is location. Location. Location. This is also true for the production of nutrients and plant pigments in leafy greens. In a greenhouse study, the influence of light intensity and soil type (texture differences) were studied in two mustard green cultivars. Light intensity was found to influence vitamin C, leaf protein, mineral nutrient and carotenoid levels, and leaf area. Soil type had a similar effect. Lower light levels and heavier textured soils tend to increase plant nutrients, with Vitamin C being one exception. Thus, environment, cultivar, and/or point of origin can have a pronounced affect on the nutritional aspects of produce. Food nutritionist and consumers need to be aware that not all leaves are the same.
A greenhouse experiment was conducted near Weslaco, Texas, (Lat. 26 deg 8' N) between 17 December 2001 and 14 February 2002 in order to evaluate the effect of soil type, light environment, and cultivar on mustard greens leaf nutrients. Cultivars Tendergreen and Florida Broadleaf (Brassica juncea) were sown in four soils, Bobillo, Hebbronville, Hidalgo, and Raymondville (listed in increasing clay content), and grown in two environments: 87 (50% shaded) and 168 MJ . m-2 (ambient) cumulative average hourly PAR having 18.2 and 19.00C mean season temperatures, respectively. Mustard greens grown under reduced PAR had lower leaf transpiration rates and ascorbic acid content, but had higher in leaf area, chlorophyll, carotenoids, total N, NO3, and most leaf mineral nutrients. Root fresh wt., but not top fresh wt. was reduced by low light. Plants grown in heavier textured soil had increased leaf area and, when grown in reduced light, pigment and leaf nutrient levels were even higher in the higher clay soils. Leaf ascorbate was higher in plants grown in ambient light than in reduced light. Folate was not affected by cultivar, light, or soil type (P<0.05).