Abstract

MILANO, Clara et al. Germinación de dos especies de Rhynchosia (Fabaceae) nativas de Argentina central útiles para la restauración productiva de pastizales naturales. RIA. Rev. investig. agropecu. [online]. 2021, vol.47, n.1, pp.88-97.  Epub June 02, 2021. ISSN 1669-2314.

The natural grasslands of southwestern Buenos Aires province (Argentina) are degraded as a result of overgrazing and the expansion of agriculture, which have generated a strong impact on biodiversity and ecosystem integrity. Productive restoration proposes the reincorporation of native species to degraded areas to restore key ecological functions and at the same time generate socio-economic and productive benefits. Legumes (Fabaceae) are a particularly useful functional group since they have multiple characteristics of agronomic interest, such as their ability to fix nitrogen, their forage quality and their meliferous potential, among others. However, information about the cultivation and use of native herbaceous legumes from central Argentina is practically non-existent. Knowledge on seminal dormancy in these species and the pregerminative treatments needed to interrupt it constitute a fundamental first step for its use. The objective of this study was to evaluate different pregerminative treatments for the germination of Rhynchosia bicentrica (Rb) and R. senna (Rs), two native herbaceous legumes species with potential to be used in the restoration of degraded grasslands. The treatments tested were manual and mechanical physical scarification, thermal scarification by immersion in water and by exposure to hot air at different temperatures and chemical scarification with sulfuric acid. The obtained results indicate that both species need pregerminative treatments that break the seminal cover to initiate the germination, since they presented percentages of physical seminal dormancy of 90 ± 5.6% (Rb) and 60.8 ± 13.5% (Rs). The manual and mechanical physical scarification treatments were effective to increase the germinative power with respect to the control in both species. For Rb, thermal scarification by exposure to water or air at constant temperature of 60 and 70°C for one hour was also effective. For Rs, thermal scarification was also effective by exposure to water at constant temperature of 70° C for 30 minutes. We discuss some advantages and disadvantages associated with the tested methods and we propose to emphasize alternatives that are applicable to scales greater than the experimental ones, highlighting the physical scarification through mechanical scarifiers and hot air exposure treatments.

Keywords : Rhynchosia bicentrica; Rhynchosia senna; legumes; productive restoration; physical dormancy; pregerminative treatments.

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