Ecological setup, ploidy diversity, and reproductive biology of Paspalum modestum, a promising wetland forage grass from South America.

Piyal Karunarathne,Cristian Feduzka,Hojsgaard Diego

doi:10.1590/1678-4685-gmb-2019-0101

Piyal Karunarathne, Cristian Feduzka + Show 1 more

Open Access

https://doi.org/10.1590/1678-4685-gmb-2019-0101

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Abstract

With ever-rising demand for food, forage breeding for intensification of cattle production is also taking a leap. In South America, cattle production systems are displaced to marginal areas poorly exploited with cultivated pastures yet with high potential for growing stocking rates. This places the need for using native genetic resources to breed locally adapted plant genotypes that benefits from better forage quality, yield, and lesser threat to the local biodiversity. Paspalum modestum Mez is a grass species that produces quality forage and grows in marginal areas like estuaries and floodplains, suitable for introduction in breeding programs. In this study we characterize the species' reproductive biology and ecological preferences needed beforehand any improvement. P. modestum plants found in nature are commonly diploids, rarely triploids, and tetraploids. Chromosome associations during meiosis in polyploids indicate they are autopolyploids. While diploids are sexual self-sterile, analyses of embryology, gamete fertility and experimental crossings show tetraploids are self-compatible facultative apomicts, highly fertile and have a high proportion of sexuality compared to other apomictic species. Ecological niche analysis and species distribution modelling show mean annual temperature and precipitation as main ecological drivers and a wide geographical area of climatic suitability where P. modestum can grow and be exploited as a forage grass. Our study points to P. modestum as a native plant resource appropriate for breeding waterlogging tolerant ecotypes and genotypes of high biomass production adapted to low flow areas in the Subtropics of Brazil, Paraguay, Uruguay and Argentina.

Highlights

At present, increasing agricultural productivity and land-use sustainability is a primary aim of most national governments and transnational organizations
The number of chromosomes of P. modestum plants collected from 7 localities (Table 1) was determined after analysing 3-10 metaphase cells (Figure 1)
Forage breeding is central for intensification of cattle production

Summary

Introduction

At present, increasing agricultural productivity and land-use sustainability is a primary aim of most national governments and transnational organizations. Clearance for agriculture and/or cattle ranching is the dominant landcover change in South America (Hansen et al, 2013). The expansion of the agricultural frontier seems to be poorly selective (e.g., Volante et al, 2016) and imposes a threat to biodiversity and environmental sustainability through landscape fragmentation, changes in productivity and carbon balance (Gasparri et al, 2008), and dissipation of primary production (Verón et al, 2012). In Argentina, Paraguay, and Brazil, cattle production systems have been subsequently displaced by agriculture into marginal areas, supporting lower livestock density per hectare. The search and use of plant materials locally adapted into breeding programs can provide better forage quality, increased forage yield, grazing options compared to introduced species, and a lesser threat to the local biodiversity

Results

Discussion

Conclusion