TITLE:
Reduction in Nitrogen Prior to Harvest Increases Phenolic Content of Baby Red Lettuce Leaves
AUTHORS:
Dario Stefanelli, Sonja Winkler, Christine Frisina, Rod Jones
KEYWORDS:
Yield, Production, Vitamin C, Antioxidant Capacity
JOURNAL NAME:
Agricultural Sciences,
Vol.5 No.6,
May
27,
2014
ABSTRACT: This study investigated baby red lettuce leaves grown in an inert media and fertigated with 300 or 1000 mg·L-1 CaNO3-N (19% Ca; 15.5% N), and the effects of altering CaNO3-N concentrations in the last 7 days prior to harvest on yield, antioxidant capacity, TPP and vitamin C content. Plants receiving 1000 mg·L-1 CaNO3-N had a significantly higher leaf FW than those fertilized with 300 mg·L-1 CaNO3-N after both 21 and 28 days. Pulsing plants with 1000 mg·L-1 CaNO3-N for 7 days after 21 days at 300 mg·L-1 CaNO3-N resulted in a significant increase in FW of 14%, compared with plants receiving 300 mg·L-1 CaNO3-N. After 28 days plants fertilized with nitrogen at 300 mg·L-1 CaNO3-N were significantly higher in TPP than those fertilized with 1000 mg·L-1 CaNO3-N. While there was no significant effect on TPP of a 7-day 1000 mg·L-1 CaNO3-N pulse added to 300 mg·L-1 CaNO3-N, a 7-day pulse of 300 mg·L-1 CaNO3-N added to 1000 mg·L-1 CaNO3-N resulted in a significant increase in TPP. These results indicate that reducing the N availability for 7 days prior to harvest can result in a significant increase in plant phenolic content with no adverse effect on yield.