Flavonol content and composition of spring onions grown hydroponically or in potting soil

Hydroponics: potential for augmenting sustainable food production in non-arable regions

Purpose

The purpose of this review of the literature is to provide readers a foundation of understanding whereby future research can move forward in the quest for global sustainable food production.

Design/methodology/approach

This review includes up-to-date information from evidence-based sources on hydroponics. Topics included are advantages, limitations, nutritional quality and sensory quality

Findings

Hydroponic growing systems offer the opportunity to at least augment traditional soil-based growing systems in global food production. Some benefits of hydroponic growing systems are limitation of water waste (recirculation), crops grown in controlled environments (control of pests, nutrients and attributes required for optimal plant growth) and ability to manipulate conditions to maximize production in limited space (vertical gardens).

Practical implications

The human population is increasing with a parallel increase in the demand for food; therefore, food production must increase to meet the need.

Originality/value

In spite of the rapid interest and proliferation of information by laypeople, evidence-based research is scant on hydroponics. This article provides a summary of the literature on hydroponics and how it may be used for sustainable food production in arid and urban areas.

Increasing the added-value of onions as a source of antioxidant flavonoids: a critical review

Flavonoids are a large and diverse group of polyphenolic compounds with antioxidant effects. While the flavonoid content and composition profile clearly reflect the genetic background of the cultivar, environmental conditions and agronomic practices are also determinants for the composition of crops at harvest. Considerable research has been directed toward understanding the nature of polyphenols in different products and the factors influencing their accumulation. This review examines the flavonoids as a class of compounds, the role these compounds play in the plant, their contributions to product quality, and recent research on the impacts of environmental factors and cultural practices on flavonoid content in onions, highlighting how this knowledge may be used to modulate their polyphenolic composition at harvest or during post-harvest handling.

Variations between diploids and tetraploids of Allium przewalskianum, an important vegetable and/or condiment in the Himalayas

Allium przewalskianum, a wild onion species growing at altitudes ranging from 1800 to 4500 m, has long been commonly used as an important vegetable and/or condiment by Tibetans, Indians, and Nepalese in the highlands of the Himalayas and adjacent regions. This species comprises both diploids and tetraploids. In this study, we examined the nutritional content and biomass accumulation profiles of two cytotypes, collected from 29 sites, with different altitudinal origins but cultivated in a common garden. On an average, this species has superior qualities in the minerals and amino acids compared to other edible congeners. When compared with the diploids, the tetraploids grew faster and accumulated more biomass; in addition, the tetraploids had higher values of moisture and energy, higher contents of cystine and phosphorus, but lower fiber levels. Moreover, the tetraploids from the higher altitudes had greater biomasses than the other tetraploids, in addition to having increased levels of proteins, fats, and the minerals Mg, Fe, Mn, and Cu. These results illustrate the large variations in nutritional efficacy and growth within this single morphological species, and provide critical information for its effective consumption in the future.