Legume protein precipitable phenolic and nutrient concentration responses to defoliation and ontogeny

Abstract

A study was conducted to determine how total phenolic (TP), protein precipitable phenolic (PPP), C, and N concentrations, and amount of protein bound (PB) by PPP in leaves of Desmodium paniculatum (panicled tick-clover; PTC) and Lespedeza cuneata (sericea lespedeza; SL) were affected by simulated herbivory and plant ontogeny. All PTC treatments resulted in a decrease (P ≤ 0.05) in TP, PPP, C, and N concentrations and PB between vegetative and seed set stages. All SL treatments resulted in increased (P ≤ 0.05) or stable TP and PPP concentrations from vegetative stage to seed set. The amount of PB was greatest (P ≤ 0.05) in SL plants submitted to 25% defoliation, and flowering and seed set stages had greater (P ≤ 0.05) PB than the vegetative stage. Ontogenesis and defoliation did not (P > 0.05) affect SL N and C concentrations. The protein binding characteristics of PPP from PTC, but not that of SL, appear to be altered in response to stress. Results might correspond with seed dispersal strategies of the two species, with PTC's epizoochory making increased palatability at seed set beneficial.

Effects of simulated and insect herbivory on nitrogen and protein precipitable phenolic concentrations of two legumes

“…The increase and subsequent decrease in N content with herbivory intensity is consistent with similar studies (Rooke and Bergström 2007;Schädler et al 2007;Cooper et al 2014). Lower N content may be due to N mobilization for leaf production; greater herbivory intensities result in fewer leaves to photosynthesize, so the plant allocates resources to produce more leaves (Culvenor and Simpson 1991;Cooper et al 2014).…”

“…The tendency for SL N content to decline with increasing herbivory intensity was consistent with findings reported by Cooper et al (2014), with the exception of the 100% defoliation which was similar to the control. Lower N availability can limit feed efficiency by reducing urea recycling and microbial efficiency in ruminants (Reed 1995) as reported for other forages containing CT (Mangan 1988).…”

“…Cooper et al (2014) found that PPP content increased from unclipped leaves to those submitted to 25% defoliation before declining for the remaining treatments. These results parallel what we observed following the second harvest, but not the first, suggesting that insect defoliation affects naive plants in a different way.…”

“…Lower N content may be due to N mobilization for leaf production; greater herbivory intensities result in fewer leaves to photosynthesize, so the plant allocates resources to produce more leaves (Culvenor and Simpson 1991;Cooper et al 2014). Alternatively, the reduction in N content could be the result of nutrient stress (Bryant et al 1993).…”

“…Proanthocyanidins include polymers of phenolic acids (ellagic acid) called tannins (Levin 1971;Chung et al 1998;Khoddami et al 2013). Within plants, tannins vary widely in concentration (Mosjidis et al 1990), structure (Fahey and Jung 1989;Chung et al 1998), allocation (Mosjidis et al 1990;Haring et al 2007), and other characteristics, which may result from the age of the plant (Stitt and Clarke 1941;Buntin 1991;Cooper et al 2014), stresses (Feeny 1976;Fales 1984;Tharayil et al 2011), or season (Stitt and Clarke 1941;Fahey and Jung 1989;Muir et al 2014).…”