SUSTAINABLE AND ORGANIC MANAGEMENT OF SELECTED FRUITS AND VEGETABLES
Title: EFFECT OF KAOLIN (SURROUND) ON PEPPER FRUIT AND SEED MINERAL NUTRIENTS
Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2005
Publication Date: December 31, 2005
Citation: Makus, D.J. 2005. Effect of kaolin (Surround) on pepper fruit and seed mineral nutrients. Subtropical Plant Science. 57:5-9.
Interpretive Summary: Semi-arid, subtropical areas, such as the Rio Grande Valley of south Texas, are subject to both high light intensity and high temperatures, with little relief from night cooling. Methods to reduce these sources of plant stresses would be desirable in order to improve fruit and vegetable quality and extend production into less favorable growth periods, such as mid-summer. Kaolin (Surround**TM), a processed aluminosilicate clay used as a particle film reflectant spray, when applied to Anaheim-type peppers, was more efficient in cooling plants in mid-summer, but not later in the season. Fruits from kaolin-sprayed plants were found to be higher in calcium, a mineral element important in the post-harvest life of peppers and other edible crops. Kaolin sprays increased fruit tissue carotenoids, an important phytonutrient group in human nutrition, and the percentage of harvested red-colored fruit late in the season. The nutrient and pigment responses to kaolin sprays appear to mimic those reported for other vegetables grown under reduced light or shade.
A kaolin-based particle film, Surround**TM, was evaluated in 2004 on an Anaheim-type pepper (Capsicum annuum) for its ability to reduce light-induced stresses and mimic shading responses reported in other vegetable crops with respect to mineral nutrient accumulation. Agronomic attributes, such as yield, were not affected by kaolin applications, but fruit tissue Ca, Na, B, and total carotenoids were increased and Al concentrations reduced by kaolin application. Late-season fruit were higher in most mineral nutrients compared to earlier harvested fruit. Seeds were little affected by kaolin, but were higher in N, P, Mg, S, Fe, Zn, Mn, and Cu and lower in K Ca, NO3, B, and Al than corresponding fruit tissue. Kaolin application did not benefit seed yield, size or germination attributes.