Biological nitrogen fixation of Biserrula pelecinus L. under water deficit

Abstract

The present work studied the effects of water deficiency conditions on the biological nitrogen fixation of three native rhizobia (SafPt12, SafPt6, and AjuPt16) isolated from Biserrula pelecinus L., and a reference strain Mesorhizobium ciceri biovar biserrulae. In terms of plant-water status, B. pelecinus showed typical signs of drought avoidance strategies such as reducing the aboveground development (i.e. reduction in leaf surface area and increase in root/ shoot ratio) in detriment of a better developed root system. Dry-matter production and nitrogen content of the aboveground biomass decreased with the increasing levels of drought stress, as well as nodulation and symbiotic nitrogen fixation, for all the tested isolates. The parameters investigated suggested that SafPt12 was the most successful native rhizobia to withstand severe water conditions without compromising nitrogen fixation demands.

An outbreak of primary photosensitisation in lambs secondary to consumption of Biserrula pelecinus (biserrula)

“…B iserrula pelecinus is a semi‐erect, self‐regenerating annual legume originating from the southern Mediterranean . Its desirable characteristics include high seed production, adaptation to a broad range of soil types, a deep root system and grazing tolerance, and these result in a highly productive pasture that is more drought resistant and shows greater self‐regeneration compared with other pasture legumes . Biserrula was first developed for agricultural use in Western Australia during the 1990s and varieties have since been introduced into a number of areas of New South Wales.…”

Species‐specific adaptations explain resilience of herbaceous understorey to increased precipitation variability in a Mediterranean oak woodland

“…; Vicente et al. ), the lack of treatment effects on either tissue N or δ 15 N does not suggest an increase in water stress on Rhizobium with increasing precipitation variability.…”

“…In Ornithopus, the rhizo-symbiotic nitrogen acquisition pattern, typical for legumes, was evident from the significantly lower tissue d 15 N, as compared to Rumex, Tolpis, and Agrostis, and the significantly higher tissue N, as compared to all other species. However, although studies have shown that N 2 fixation in legumes is sensitive to moisture deficiency (e.g., Serraj et al 1999;Vicente et al 2012), the lack of treatment effects on either tissue N or d 15 N does not suggest an increase in water stress on Rhizobium with increasing precipitation variability.…”

Broad environmental tolerance of native root-nodule bacteria ofBiserrula pelecinusindicate potential for soil fertility restoration

“…Relatively few isolates were considered to efficiently fix N, emphasising the extremely specific relationship between B. pelecinus and its micro-symbiont (Howieson et al 1995;Nandasena et al 2004). The B-value, δ 15 N from N 2 fixing-plant when totally dependent on N 2 as the only N source, was determined as −3.53‰ (Vicente 2010) and the N dfa (the fraction of N derived entirely from N 2 fixation) estimated from the more efficient B. pelecinus root-nodule bacteria ranged between 67% and 73%. The difference between δ 15 N in the reference crop (δ 15 N ref = 7.16‰) and B-value (δ 15 N = −3.53‰) was more than five δ 15 N units, ensuring the other precondition for NA application (Högberg 1997).…”

“…The B-value used was −3.53‰ calculated elsewhere (Vicente 2010). The total amount of N in the plant derived from N 2 fixation (N fix ) was determined by N fix = N dfa × N content.…”