Effects of ultraviolet‐B irradiance on soybean. VI. Influence of phosphorus nutrition on growth and flavonoid content

Abstract

Miuali, N. S. and Teramura, A. H. 1985. Effects of ultraviolet-R irradiance on soybean. VI. Influence of phosphoius nutrition on growth and flavonoid content. -Physiol. PlarU. 63: 413-416.Soybeans CSlycine ma.x (L.) cv. Essex were hydroponically grown in a greenhouse at 2 levels ot ultraviolet-\i (UV-B) radiation (t) and 2 5t)0 .) ni ' day ' biologically effective UV-B radiation) and 4 levels of P (6.5. 13, 26 and 52 /xA-f). Plants were grown in each treatment combination to the complete expansion of the 4th trifoliolate leaf. UV-H radiation and redueed P supply generally deereased plant height, leaf area and total biomass. but increased specific leaf weight and flavonoid content (measured as absorbanee of methanolic extracts). Although both UV-B radiation and low P supply produced deleterious effects on plant biomass, the effects were non-additive. The eotnbination of UV-B and the lowest P level (6.5 /iM) had no effeet on total biomass or leaf area. This was at least partially due to the aeeumulation of flavonoids and leaf thieketiing. The tesults show that the sensitivity of soybean to UV-B radiation is dependent upon plant P supply. Plants experiencing P deficiency are less sensitive to UV-B than plants at optimum P levels.Additional key words -CSlycine max, ozone depletion, stress interaetions.

Arbuscular mycorrhizal fungi and the occurrence of flavonoids in roots of passion fruit seedlings

“…High levels of formononetin in roots of Trifolium can be induced by phosphorus stress in the plant . Phosphorus deficiency and irradiation with UV-B rays increase significantly the contents of flavonoids in the soybean leaves (Murali & Teramura, 1985). In soybeans, nitrogen fertilization caused a decrease in the concentration of isoflavonoids in the roots, and in Lupinus albus, the nitrate reduced the quantity of the present flavonoids in the root extracts (Coronado et al, 1995).…”

“…The accumulation of flavonoids due to nutritional stresses of nitrogen and phosphorus has been demonstrated in leguminous plants (Coronado et al, 1995;Nair et al, 1991;Murali & Teramura, 1985). High levels of formononetin in roots of Trifolium can be induced by phosphorus stress in the plant .…”

“…Ponce et al (2004) identified several flavonoids from cold ethanolic extracts of dried shoots and roots of Trifolium repens (white clover), grown with and without Glomus intraradices, and concluded that the metabolism of these compounds is strongly affected by the AMF colonization. The concentration of flavonoids in leguminous roots varies with root colonization with mycorrhizal fungi, the stages of interaction between the plant and its symbiont (Lum & Hirsch, 2003;Hirsch & Kapulnik, 1998;Volpin et al, 1994), and with deficiency of nitrogen and/or phosphorus (Coronado et al, 1995;Nair et al, 1991;Murali & Teramura, 1985). Table 1 shows the concentrations of the compounds represented by the seven major chromatograph peaks, as a result of treatments (seedling inoculation with AMF, and phosphorus levels).…”

The effect of u.v.‐B radiation on u.v.‐absorbing secondary metabolites in birch seedlings grown under simulated forest soil conditions

“…Taking into account the carbon/nutrient balance hypothesis (Bryant et al, 1983;Coley et aL, 1985), it might be that these growth conditions have induced an increased general synthesis of secondary metabolites and that this, combined with the u.v.-B-induced synthesis of some speciflc compounds, has provided the plants with adequate protection against the applied dose of u.v.-B radiation. Deflciencies in N, P, S and K have all been reported to increase the production of secondary metabolites (Gershenzon, 1984;Murali & Teramura, 1985;Hakulinen et al, 1995) by regulating either the expression of enzymes involved in biosynthesis of phenolic compounds (Margna, Margna & Vainjarv, 1989;Bongue-Bartelsman & Phillips, 1995) or the availability of substrates. We conclude that several types of phenolic compounds in seedlings of B. pendula respond to u.v.-B irradiance, and that seedlings are less susceptible to u.v.-radiation when grown at the low availability of minerals that occurs in forest soil (higher phenolic level).…”

“…Conifers, which appear to be most efficient in u.v.-screening (Day, Howells & Rice, 1994), have shown considerable speciesspecific and individual variation in susceptibility to enhanced u.v.-B radiation, as well as in the u.v.-B-induced accumulation of u.v.-B absorbing compounds (Sullivan & Teramura, 1988. This response to u.v.-B radiation has been shown to be highly dependent upon growth conditions, such as illumination and mineral availability (see, for example, Murali & Teramura, 1985;Bornman & Teramura, 1993).…”