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INVESTIGATOR: Tharayil, N.

PERFORMING INSTITUTION:
CLEMSON UNIVERSITY
CLEMSON, SOUTH CAROLINA 29634

STRESS INDUCED MODIFICATION OF THE QUANTITY AND COMPOSITION OF PHYTOCHEMICALS IN FRUITS: OPTIMIZING THE NITROGEN SUPPLY FOR ENHANCING THE NU

NON-TECHNICAL SUMMARY: In the present day, where human health often drives the consumer's food choices, increased attention is given to the quality of fruits and vegetables due to their abundance in phytochemicals. Although the production of these protective compounds are generally higher in plants exposed to resource limited conditions, the current production practices of fruits and vegetables are optimized for higher fruit yield. As a consequence, crops grown under optimal conditions to achieve maximum yield may not necessarily develop their full potential for phytochemicals. Using strawberries as a model crop, the main objectives of the proposed research are to optimize production practices i) that balance between fruit yield and phytochemical content and ii) that would alter the composition of phytochemicals in the fruit for a better overall biological nutritive value. Based on this physiology of stress mitigation in plants we hypothesize that i) the total phytochemical content of strawberries will respond non-linearly to decreasing nitrogen (N) supply and ii) along with the changes in their total quantity, the composition and efficiency of phytochemicals would also change with the level of N supply. We will conduct both greenhouse and field experiments to test the effect of different levels of N treatment on the total content and composition of phenolic compounds in different strawberry cultivars. A metabolomics approach will be used to quantify the major metabolites and stable intermediaries in fruits that originate from Calvin cycle, glycolysis, pentose phosphate pathway, urea cycle, shikimate pathway and phenylpropanoid pathway. The nutritional quality of berries will be quantified through antioxidant assays. We further aim to develop a field based assay that will provide information on the phytochemical content of fruit for grower use in marketing programs.

OBJECTIVES: In the present day, where human health often drives the consumer's food choices, increased attention is given to the quality of fruits and vegetables due to their abundance in phytochemicals. Despite the production of these protective compounds being higher in plants exposed to resource limited conditions, the current production practices of fruits and vegetables are optimized for higher fruit yield. The production of phytochemicals in fruits and vegetables are strongly regulated by the environment, as these compounds protect the plants from biotic and abiotic stresses. As a consequence, crops grown under optimal conditions for maximum yield may not necessarily develop their full potential for phytochemicals. The above contrasting association between quantitative yield and nutritive value of fruits and vegetables call for a paradigm shift in cultivation practices that currently are focused on maximizing yield.The overall goal of the project is develop management recommendations whereby growers will be able to enhance and promote the nutritional qualities of strawberries in order to take advantage of increasing markets for healthy foods. Using strawberries as a model crop, the main objectives of the proposed research are to optimize production practices i) that balance between the fruit yield and phytochemical content and ii) that would alter the composition of phytochemicals in the fruit for a better overall biological nutritive value. Further, the project aim is to develop a field-based assay that would robustly capture the phytochemical content of the fruits, which would enable farmers to determine and advertise the overall nutritive value of the produce for quality assessment and marketability.