BIOMASS AND CHEMICAL RESPONSES OF Desmanthus spp. ACCESSIONS SUBMITTED TO WATER DEPRIVATION1

Abstract

Due to the predictions of climate change, there is a need to identify forage plants that can keep their productivity and nutritive value under hydric stress. The objective of this study was to evaluate the biomass and chemical responses of three Desmanthus spp. accessions under two water deprivation regimens (7 and 21-day). The experimental design used was randomized blocks in a 3 × 2 factorial arrangement (access and water deprivation) with four replications. There were reductions in the biomasses of leaf and stem fractions of 64% and 51%, respectively. The 43F accession showed greater leaf (1.86 g.plant-1) and stem (1.97 g.plant-1) biomasses under a total water restriction of 21 days, compared to the 89F and AusT accessions. In accessions 43F and 89F, there were carbohydrate accumulations in the leaves of 28% and 51%, respectively, under the 21-day water restriction, while AusT decreased 38% within a 7-day interval. Water deprivation affected the chemical characteristics of the accessions. Free proline was similar among accessions and accumulated 463% more in the leaves of plants submitted to 21-day water deprivation (90.22 mg.kg-1) compared to those subjected to water deprivation for 7 days (16.03 mg.kg-1). Proline and total soluble carbohydrate accumulation in 43F and 89F were insufficient to regulate crude protein, C content, and C:N ratios. These results demonstrate the variability in drought tolerance among accessions. Accessions 43F and 89F were more susceptible to 21-day water deprivation, while AusT showed greater drought tolerance.

Morphology, accumulation and survival of Desmanthus under different planting densities and harvest heights

“…The morphological changes and reduction in productive characteristics observed (Tables 2 and 4) may result from restricted leaf expansion (Liu et al, 2021) and reduced photosynthetic capacity (Queiroz et al, 2021) under water deficit in the harvests carried out in the dry season (October/2018, December/2018, November/2019 and February/2020; Figure 1). These changes may constitute a mechanism of adaptation of Desmanthus to such conditions, reducing the exposure of the leaves to the sun and, therefore, the surface area for water loss.…”

“…The irregular distribution of rainfall influences forage production and quality, restricting livestock production (Rocha Filho et al, 2021). When considering climate change forecasts, droughts will become more intense and frequent (Liu et al, 2021; Queiroz et al, 2021). In this context, the cultivation of native species adapted to such conditions, can make livestock farming viable in regions with water scarcity (Cabrera et al, 2016), in addition to enabling the recovery of degraded or unproductive areas.…”

Morphological and productive characterization of Macroptilium lathyroides (L.) Urb. native to the semi-arid region of Brazil

“…It is possible, thus, that these climatic changes in the last cycle have limited soil water availability and consequently foliar development. Morphological changes and reduction of productive characteristics were observed by Medeiros et al (2023) working with native legume Desmanthus pernambucanus [L.] Thellung plants, associated with restricted leaf expansion (Liu et al, 2021) and reduced photosynthetic capacity (Queiroz et al, 2021) under water deficit conditions. The accessions that stood out in the first two cycles in the leaf width (62F) and leaflet length (81F), had stronger declines between the second and third cycles of 56 and 71%, respectively (Table 3).…”

Exchange of germoplasm and genetic diversity to enrichment the Desmanthus genebank

“…They stand out by their high protein content, resistance to droughts, and regrowth and colonization capacity. They present no toxicity to animals and high nutritional value (COSTA et al, 2017;QUEIROZ, et al, 2021). These plants are palatable, present high yields (ARAGÃO et al, 2019), are tolerant to droughts, and present high seed production, which is a key-component for persistence of plants (QUEIROZ, 2016).…”