acid content in the organically grown hot pepper (OG) was significantly higher
than the conventionally grown hot pepper (CG). Also, the content flavonoids
(apigenin, luteolin, quercetin) and total phenolics in OG was typically higher than
in CG. Organic practices also increased the ABTS radical-scavenging of red fruits.
Mitchell et al. (2007) established similar findings in a 10-year comparison of the
OG and CG on the flavonoid content in tomatoes.
Organic manure and mineral fertilizers have a positive effect on the antioxidant,
polyphenols, and total carotenoid content, nevertheless, with the association of the
two fertilizers major results are obtained. Combinations using doses of nitrogen,
phosphorus, and potassium of 15, 30, and 45 kg/ha, respectively, associated with
an annual or biennial fertilizer of 20 ton/ha gave the highest values of total
antioxidant, polyphenolic, and carotenoid concentrations in Orange-fleshed
sweetpotato tubers (Koala et al. 2013). It is postulated that fertilization with
growth-limiting nutrients will lead to decreased concentrations of carbon-based
secondary metabolites. This statement is known as the carbon/nitrogen balance
(CNB) hypothesis (Bryant et al. 1983). Some studies have followed the predictions
of this hypothesis while others have failed (Millard and Way 2011).
Roussos et al. (2011) stated that apricot cultivar subjected to fruit thinning
during pit hardening, enhanced the morphological traits of apricot fruits as well as
their phytochemical content. Biotic and abiotic stress could increase the presence
of secondary metabolites in plants. Navarro et al. (2006) indicate that peppers
collected in the red state presented an increase in antioxidant activity, total
phenolics, ascorbic acid, lycopene, and b-carotene when moderate-saline (15 mM)
irrigation water is used. It has been found that the content of b-carotene in tomato
increased as the quality of irrigation water decreased. Decreased irrigation caused
the glucosinolate content to double in broccoli. Deficit irrigation strategies are
tools for managing plant growth and improving fruit quality and water use efficiency, while maintaining yields. Stefanelli et al. (2010) investigate the effect of
minimal water use in a wide range of crops concluding that by carefully manipulating nutrient elements in horticulture it is possible to obtain both fruit quality
and yield.
Many studies indicate that plants exposed to high or low (29–33 or 11–16 °C),
rather than optimal intermediate growth temperatures (21 °C), produce the highest
levels of glucosinolates (Björkman et al. 2011). Other factors that impact the
plant’s secondary metabolite content are the light intensity (irradiation), photoperiod, and light quality (wavelength). Plants have developed protective mechanisms against damaging elevated doses of UV radiation (280–315 nm) and
extreme light intensities. UV-B radiation impacts on the levels of secondary
metabolites like phenolic compounds, terpenoids, and alkaloids. Long periods
seem to have a positive effect on glucosinolate content. Broccoli sprouting in light
had higher total glucosinolate levels in roots and shoots when compared to the
ones in darkness (Pérez-Balibrea et al. 2008).
Additionally to environmental factors, plants are subjected to biotic stress such
as herbivore and pathogenic attacks. Perception, transduction, and propagation of
1 Strategies for Sustainable Plant Food Production
33
than the conventionally grown hot pepper (CG). Also, the content flavonoids
(apigenin, luteolin, quercetin) and total phenolics in OG was typically higher than
in CG. Organic practices also increased the ABTS radical-scavenging of red fruits.
Mitchell et al. (2007) established similar findings in a 10-year comparison of the
OG and CG on the flavonoid content in tomatoes.
Organic manure and mineral fertilizers have a positive effect on the antioxidant,
polyphenols, and total carotenoid content, nevertheless, with the association of the
two fertilizers major results are obtained. Combinations using doses of nitrogen,
phosphorus, and potassium of 15, 30, and 45 kg/ha, respectively, associated with
an annual or biennial fertilizer of 20 ton/ha gave the highest values of total
antioxidant, polyphenolic, and carotenoid concentrations in Orange-fleshed
sweetpotato tubers (Koala et al. 2013). It is postulated that fertilization with
growth-limiting nutrients will lead to decreased concentrations of carbon-based
secondary metabolites. This statement is known as the carbon/nitrogen balance
(CNB) hypothesis (Bryant et al. 1983). Some studies have followed the predictions
of this hypothesis while others have failed (Millard and Way 2011).
Roussos et al. (2011) stated that apricot cultivar subjected to fruit thinning
during pit hardening, enhanced the morphological traits of apricot fruits as well as
their phytochemical content. Biotic and abiotic stress could increase the presence
of secondary metabolites in plants. Navarro et al. (2006) indicate that peppers
collected in the red state presented an increase in antioxidant activity, total
phenolics, ascorbic acid, lycopene, and b-carotene when moderate-saline (15 mM)
irrigation water is used. It has been found that the content of b-carotene in tomato
increased as the quality of irrigation water decreased. Decreased irrigation caused
the glucosinolate content to double in broccoli. Deficit irrigation strategies are
tools for managing plant growth and improving fruit quality and water use efficiency, while maintaining yields. Stefanelli et al. (2010) investigate the effect of
minimal water use in a wide range of crops concluding that by carefully manipulating nutrient elements in horticulture it is possible to obtain both fruit quality
and yield.
Many studies indicate that plants exposed to high or low (29–33 or 11–16 °C),
rather than optimal intermediate growth temperatures (21 °C), produce the highest
levels of glucosinolates (Björkman et al. 2011). Other factors that impact the
plant’s secondary metabolite content are the light intensity (irradiation), photoperiod, and light quality (wavelength). Plants have developed protective mechanisms against damaging elevated doses of UV radiation (280–315 nm) and
extreme light intensities. UV-B radiation impacts on the levels of secondary
metabolites like phenolic compounds, terpenoids, and alkaloids. Long periods
seem to have a positive effect on glucosinolate content. Broccoli sprouting in light
had higher total glucosinolate levels in roots and shoots when compared to the
ones in darkness (Pérez-Balibrea et al. 2008).
Additionally to environmental factors, plants are subjected to biotic stress such
as herbivore and pathogenic attacks. Perception, transduction, and propagation of
1 Strategies for Sustainable Plant Food Production
33