Trocas gasosas em leguminosas e seus efeitos sobre a comunidade de macroartrópodes do solo.

Abstract

The use of legume plant species as green manuring is a conservationist practice that promotes the sustainability of agricultural soils. Our aim here, was to evaluate the gaseous exchanges pattern and agronomic characteristics of different legume species used as green manure, and in turn how could these legume species impact the soil macroarthropod community. We used an experimental randomized blocks design distributed in eight treatments (Crotalaria juncea L., Crotalaria spectabilis Roth, Crotalaria ochroleuca G. Don., Canavalia ensiformes (L.) DC., Dolichos lablab L., Mucuna pruriens (L.) DC., Neonotonia wightii (Wight & Arn.) J.A. Lackey and, spontaneous vegetation) with three replications (N = 24). To evaluate the gaseous exchanges pattern and agronomic characteristics of the studied legume species, we analysed: photosynthetic rate, leaf transpiration, stomatal conductance, CO2 internal concentration, instantaneous water use efficiency, instantaneous carboxylation efficiency, water use efficiency, growth rate, fresh and dry biomass and nutrient content in the plant; and to evaluate the effects of different species of green manure, we analysed: abundance, relative frequency, dry biomass, species richness, Shannon Diversity index (H) and Simpson dominance index (C). We found that C. juncea presented the highest physiological rates, reflecting greater adaptability in the humid zone conditions of the Brazilian semiarid, whereas D. lablab presented the highest values of growth rate, dry biomass, and N content in the leaves. Also, all the studied legume species positively changed soil macroarthropod abundance and richness. There was a positive correlation between high biomass production by legume species and soil macroarthropod diversity. Our results highlight the importance to consider soil macroarthropod as bioindicator used to evaluate the impacts of different species of covering, in new areas.