222 research outputs found
Growth and nutrition of cowpea (Vigna unguiculata) under water deficit as influenced by microbial inoculation via seed coating
Drought can drastically reduce cowpea [Vigna unguiculata (L.) Walp.] biomass and grain yield. The application of plant growthâpromoting rhizobacteria and arbuscular mycorrhizal fungi can confer resistance to plants and reduce the effects of environmental stresses, including drought. Seed coating is a technique which allows the application of minor amounts of microbial inocula. Main effects of the factors inoculation and water regime showed that: severe or moderate water deficit had a general negative impact on cowpea plants; total biomass production, seed weight and seed yield were enhanced in plants inoculated with P. putida; inoculation of R. irregularis significantly increased nitrogen (N) and phosphorus (P) shoot concentrations; and R. irregularis enhanced both chlorophyll b and carotenoids contents, particularly under severe water deficit. Plants inoculated with P. putida + R. irregularis had an increase in shoot P concentration of 85% and 57%, under moderate and severe water deficit, respectively. Singly inoculated P. putida improved potassium shoot concentration by 25% under moderate water deficit. Overall, in terms of agricultural productivity the inoculation of P. putida under water deficit might be promising. Seed coating has the potential to be used as a largeâscale delivery system of beneficial microbial inoculants.info:eu-repo/semantics/publishedVersio
Herbivore Preference for Native vs. Exotic Plants: Generalist Herbivores from Multiple Continents Prefer Exotic Plants That Are Evolutionarily NaĂŻve
Enemy release and biotic resistance are competing, but not mutually exclusive,
hypotheses addressing the success or failure of non-native plants entering a new
region. Enemy release predicts that exotic plants become invasive by escaping
their co-adapted herbivores and by being unrecognized or unpalatable to native
herbivores that have not been selected to consume them. In contrast, biotic
resistance predicts that native generalist herbivores will suppress exotic
plants that will not have been selected to deter these herbivores. We tested
these hypotheses using five generalist herbivores from North or South America
and nine confamilial pairs of native and exotic aquatic plants. Four of five
herbivores showed 2.4â17.3 fold preferences for exotic over native plants.
Three species of South American apple snails (Pomacea sp.)
preferred North American over South American macrophytes, while a North American
crayfish Procambarus spiculifer preferred South American,
Asian, and Australian macrophytes over North American relatives. Apple snails
have their center of diversity in South America, but a single species
(Pomacea paludosa) occurs in North America. This species,
with a South American lineage but a North American distribution, did not
differentiate between South American and North American plants. Its preferences
correlated with preferences of its South American relatives rather than with
preferences of the North American crayfish, consistent with evolutionary inertia
due to its South American lineage. Tests of plant traits indicated that the
crayfish responded primarily to plant structure, the apple snails primarily to
plant chemistry, and that plant protein concentration played no detectable role.
Generalist herbivores preferred non-native plants, suggesting that intact guilds
of native, generalist herbivores may provide biotic resistance to plant
invasions. Past invasions may have been facilitated by removal of native
herbivores, introduction of non-native herbivores (which commonly prefer native
plants), or both
Phytotoxic Effects of (±)-Catechin In vitro, in Soil, and in the Field
BACKGROUND: Exploring the residence time of allelochemicals released by plants into different soils, episodic exposure of plants to allelochemicals, and the effects of allelochemicals in the field has the potential to improve our understanding of interactions among plants. METHODOLOGY/PRINCIPAL FINDINGS: We conducted experiments in India and the USA to understand the dynamics of soil concentrations and phytotoxicity of (+/-)-catechin, an allelopathic compound exuded from the roots of Centaurea maculosa, to other plants in vitro and in soil. Experiments with single and pulsed applications into soil were conducted in the field. Experimental application of (+/-)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations. Pulses replenished (+/-)-catechin levels in soils, but consistently at concentrations much lower than were applied, and even pulsed concentrations declined rapidly. Different natural soils varied substantially in the retention of (+/-)-catechin after application but consistent rapid decreases in concentrations over time suggested that applied experimental concentrations may overestimate concentrations necessary for phytotoxicity by over an order of magnitude. (+/-)-Catechin was not phytotoxic to Bambusa arundinacea in natural Indian soil in a single pulse, but soil concentrations at the time of planting seeds were either undetectable or very low. However, a single dose of (+/-)-catechin suppressed the growth of bamboo in sand, in soil mixed with organic matter, and Koeleria macrantha in soils from Montana and Romania, and in field applications at 40 microg l(-1). Multiple pulses of (+/-)-catechin were inhibitory at very low concentrations in Indian soil. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that (+/-)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in the field. However, there is substantial conditionality in the effects of the allelochemical
- âŠ