Physiological and production responses of four grasses from the genera Urochloa and Megathyrsus to shade from Melia azedarach L.

Silvopastoral system (SPS) has been suggested to ensure sustainability in animal production systems in tropical ecosystems. The objective of this study was to evaluate the productive and nutritive value traits of Brachiaria decumbens and performance of dairy heifers in SPS and open pasture (OP) during the summer and autumn of two consecutive years in the SPS and OP (17th and 18th years after establishment). Experimental design was a randomized complete block with two treatments (SPS and OP) and three replications in subdivided plots with repeated measures in time. There was reduction in the tiller population density, total and green forage mass, and total and green forage bulk density in the SPS when compared to the OP in the summer. In the autumn, no difference was observed between the systems. Shading in SPS increased crude protein content of the grass pasture by 25% and 33% when compared to the OP during the first and second experimental years, respectively, and reduced neutral detergent fibre content. However, it did not change acid detergent fibre or lignin content. OP provided higher stocking rate and weight gain per area than the SPS. Average daily gain was higher in the OP in the second experimental year. Severe shading conditions should be avoided, because in the long‐term they may threaten the persistence and sustainability of pasture in the SPS. It is recommended to plant a low density of trees or implement management strategies of the tree component by either thinning or pruning over the years after planting.

Section: Discussionmentioning

confidence: 99%

Productivity and nutritive value of Brachiaria decumbens and performance of dairy heifers in a long‐term silvopastoral system

Lima

Paciullo

Morenz

et al. 2018

“…Competition for light between trees and herbaceous components is an important consideration in silvopastoral system management (Neel et al ., , ; Santiago‐Hernández et al ., ). Shading of more than 50% of the incident radiation can affect the biomass production of tropical forage grasses (Guenni et al ., ; Abraham et al ., ), because of the reduced photosynthetic rates in C 4 grasses (Santiago‐Hernández et al ., ). However, under moderate shading, herbage production may be similar or even greater than that observed in open pastures (Kyriazopoulos et al ., ; Paciullo et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Morphogenesis, biomass and nutritive value of Panicum maximum under different shade levels and fertilizer nitrogen rates

Paciullo

Gomide

Castro

et al. 2016

Panicum maximum is important for cattle production in tropical regions, and it responds well to nitrogen (N) fertilization. Many cultivars have exhibited potential for use in silvopastoral systems, although there is limited information on how different levels of N can influence plant growth and nutritive value under shading. Morphogenetic and structural traits, biomass production and nutritive value of two P. maximum cultivars (Tanzânia and Massai) were investigated under three shading levels (0, 37 and 58%) and four N rates (0, 50, 100 and 150 mg N dm À3 ). Plants were grown in pots under shade. Leaf and stem elongation rate and leaf blade length increased with shading and in response to N. Tiller density was reduced with shading, but showed a linear increase fashion with N under full sun and moderate shading. Under intense shading, the tillering showed a quadratic response to N. Plant biomass production increased linearly with N under full sun and moderate shade, but it increased quadratically under intense shade. Crude protein (CP) content increased with shade and N and was greater for Tanzânia than Massai under shade. Contents of NDF and ADF were greater for Massai than Tanzânia. Acid detergent insoluble protein was reduced in Tanzânia under shade, but it increased for Massai. It is suggested that the positive shading effect on CP content may not result in increased nutritional value. Although N fertilization was important for increasing biomass production under full sun and moderate shade, it should be avoided under intense shading.

“…While RUE values for temperate forage and grain legumes are well documented (Giunta, Pruneddu, & Motzo, 2009;Sinclair & Muchow, 1999;St€ ockle & Kemanian, 2009), information regarding variation in light interception and use by tropical forages is limited to few species (Cruz, 1995;Fisher & Cruz, 1994;Squire, 1990;Wilson & Ludlow, 1991;Wong & Wilson, 1980), and recent reports on the effects of decreased light on the acclimation potential of structural and functional traits at leaf and canopy level are even more scant (Baligar, Bunce, Elson, & Fageria, 2010;Dias-Filho, 2002; G omez, Guenni, & Bravo de Guenni, 2013;Paciullo et al, 2017;Santiago-Hern andez et al, 2016).…”

mentioning

confidence: 99%

Influence of low light intensity on growth and biomass allocation, leaf photosynthesis and canopy radiation interception and use in two forage species of Centrosema (DC.) Benth.

Guenni

Romero

Guedez

et al. 2018

Sustainable silvopastoral systems rely on the capacity of forage species to withstand shade, competition for soil resources and grazing. On a field‐plot experiment, we studied the effects of artificial shade on the performance of two tropical forage legumes: Centrosema molle (CIAT 15160) and C. macrocarpum (CIAT 5713). Acclimation to shade in these two species was investigated at individual leaf and whole canopies, to explain differences in the efficiency of radiation interception and use, and thus forage yield. Under 30% sunlight, midday leaf net photosynthesis (A) was reduced by 32%–44%, although instantaneous light use efficiency increased up to 44%–140%. Almost 50% increase in leaf specific area was accompanied by 61% in total chlorophyll content. From analysis of the light‐response curves, net photosynthesis at light saturation was only reduced (by 36%) in C. macrocarpum. Efficiency of chloroplast photosystem II (PSII) was unaffected by shade. Canopy structure for light interception was not modified by shade, although conversion into biomass and final yield were significantly reduced (40%–43%) in C. macrocarpum. Results are discussed in terms of factors affecting potential acclimation to shade and the agronomic implications of using both forage legumes in mixed pastures under tree canopies.