Submitted to: Plant Foods for Human Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2001
Publication Date: 9/7/2004
Citation: Russo, V.M., Biles, C. 2003. Fertilizer rate and beta galactosidase and peroxidase activity in pepper fruit at different stages and years of harvest. Plant Foods for Human Nutrition. 58:231-239.
Interpretive Summary: Cultural practices can affect physiological processes in plants. Improper nutrition can hinder optimal development of plants. In peppers this may be expressed in terms of pungency. Two fertilizer rates were used to determine if nutrient levels affected activities of the enzymes B- galactosidase and peroxidase in pods of non-pungent (five bell cultivars), and pungent (four different types) peppers harvested at the mature green, turning, and red color stages. High levels of B-galactosidase cause cell walls to quickly soften, and high levels of peroxidase reduces pungency. Plants treated with the higher fertilizer rate had increased B- galactosidase activity, but peroxidase activity was not affected. Red fruit always had higher B-galactosidase activity, but only occasionally higher peroxidase activity. The various types of peppers exhibited different patterns for activities of these enzymes as pods matured. Non- pungent peppers had higher peroxidase activity than pungent peppers. Manipulation of cultural practices affecting expression of activity of these enzymes may affect fruit pungency and shelf-life.
Technical Abstract: B-galactosidase has been implicated in fruit softening, and increased peroxidase activity may play a role in oxidation of capsaicins. However, the effect of cultural practices on B-galactosidase and peroxidase activity in peppers is not well understood. This project was undertaken to determine if fertilizer rate affects activity of these enzymes. Five non- pungent and four pungent pepper cultivars were grown in field plots fertilized at two rates in 1997 and 1998 at Lane, OK, USA. Fruit were harvested at mature green, turning, and red color stages, and assayed for B-galactosidase and peroxidase activity. Over all fruit B-galactosidase activity increased as fertilizer rate increased, and was highest in red fruit. Fertilizer rate and fruit developmental stage in 1997 did not affect peroxidase activity, but peroxidase activity was highest in red fruit in 1998. Enzyme activity appeared to be cultivar dependent, and patterns differed in both years. Activities of both enzymes were higher a the red stage in many non-pungent peppers as in pungent peppers. Manipulation of cultural practices that affect the expression of activity of these enzymes may affect fruit pungency and shelf-life.