Urochloa in Tropical Agroecosystems

Abstract

Increasing biodiversity is an important issue in more secure and sustainable agriculture. Diversified systems are more resilient to climate change, environmental stresses and enhance soil health, nutrient cycling and nutrient use efficiency. In tropical agroecosystems, cover crops and intercrops are an alternative toward a more diverse and sustainable production. Urochloa spp. (syn. Brachiaria spp.) are perennial grasses, known for their high biomass production. They are commonly used as cover and companion crops in conservation agriculture in the tropics and the residues left in the field after cutting protect the soil and provide nutrient to the next crop cycle or intercropped culture. Urochloa species roots are vigorous, abundant and deep, as opposed to the more shallow and scarce roots of common crops. These traits contribute to carbon sequestration, soil organic matter stabilization and nutrient cycling. Urochloa roots also improve soil physical characteristics and influence soil nutrient dynamics, reducing nutrient losses and enhancing cycling, what is key to achieve greater nutrient use efficiency in agriculture. For instance, Urochloa root exudates can reduce nitrogen losses by denitrification and leaching through a process called biological nitrification inhibition; root exudates can mobilize recalcitrant phosphorus from soils and make it available for plant uptake; the deep roots of these grasses have the potential to recover nutrients that are virtually lost away from the root zone of other crops. This review compiles scientific progress regarding the introduction of Urochloa in agroecosystems, mainly on the aspects related to the contribution to more secure and sustainable agriculture.

Flow Cytometry-Based Determination of Ploidy from Dried Leaf Specimens in Genomically Complex Collections of the Tropical Forage Grass Urochloa s. l.

“…In exploiting biodiversity in breeding, improvements in yield and nutritional quality of forages can be achieved by identifying genes increasing the digestibility of plant cell walls and the protein and lipid content in vegetative tissues, and increasing biomass production [ 4 ]. By introduction to plant breeding programmes, genetic improvement of forage lines, recurrent genetic selection of plants showing useful traits, and subsequent hybridizations and back-crossings [ 5 , 6 ], create more diverse agroecosystems resilient to climate and environmental changes [ 7 ]. The DNA amount measurement for ploidy and genome size estimation, and the characterization of genome composition are required for effective use of diploids and polyploids in breeding programs, as well as for research purposes [ 8 , 9 ].…”

Early nitrogen supply as an alternative management for a cover crop-maize sequence under a no-till system

“…1. One letter: different lowercase letters denote significant differences between cover crops and N application timing interaction; two letters: different lowercase letters denote significant differences between cover crops and different uppercase letters denote significant differences among N application timing; ns: no statistically significant difference (LSD, P B 0.05) with other cover crops such as sun hemp (Crotalaria juncea) and pearl millet (Pennisetum glaucum) (Fisher et al 1995;Borghi et al 2013;Baptistella et al 2020). Several studies have highlighted differences among Urochloa spp.…”

Differential responses of three Urochloa species to low phosphorus availability

“…Urochloa has also been used in agroecosystems as an alternative to crop rotation in no‐tillage systems and as a companion crop in intercrops with annual and perennial species, serving both as a cover crop and pasture, especially in Brazil (Bieluczyk et al, 2020; de Almeida, Favarin, et al, 2018; Favarin, de Souza, Moscardini, & Baptistella, 2018). Introduction of Urochloa in the agroecosystem can provide multiple services, such as erosion control, soil aggregation, carbon sequestration, increased water availability, nutrient cycling and nutrient use efficiency (NUE; Baptistella, de Andrade, Favarin, & Mazzafera, 2020).…”