Death of pastures syndrome: tissue changes in Urochloa hybrida cv. Mulato II and Urochloa brizantha cv. Marandu.

N G Ribeiro-Júnior,A P R Ariano,I V Silva

doi:10.1590/1519-6984.10715

N G Ribeiro-Júnior, A P R Ariano + Show 1 more

Open Access

https://doi.org/10.1590/1519-6984.10715

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Abstract

The quality of forage production is a prerequisite to raising livestock. Therefore, income losses in this activity, primarily cattle raising, can result in the impossibility of economic activity. Through the qualitative and quantitative anatomical study of Urochloa hybrida cv. Mulato II and U. brizantha cv. Marandu, we searched for descriptions and compared changes in the individual vegetative body from populations with death syndrome pastures (DPS). Specimens were collected at different physiological stages from farms in northern Mato Grosso. After collection, the individuals were fixed in FAA50 and stored in 70% alcohol. Histological slides were prepared from the middle third of the sections of roots, rhizomes, and leaves, and the proportions and characteristics of tissues were evaluated in healthy, intermediate, and advanced stages of DPS. Changes were compared between cultivars. With the advancement of the syndrome, the following changes were observed: a more marked decrease in the length of roots in U. hybrida; disorganization of the cortical region of the roots and rhizome cultivars; fungal hyphae in roots and aerenchyma formation in U. hybrida; a decrease in sclerenchyma fiber proportions in roots and leaves; sclerification of the epidermis of U. brizantha rhizomes; and an increase in pericyclic fibers in U. hybrida. Furthermore, there was a decrease in the volume of epidermal cells of the abaxial face of the leaves of both cultivars, with a greater reduction in U. hybrida; a gradual decrease in thickness in the midrib of leaves similar to leaf mesophyll; conduction system obstructions; partial or total cell lysis in roots and rhizomes affected by the syndrome. Obstructions in sieve tube element and companion cells, and sometimes obstruction in xylem vessel elements. The evolution of DPS in cultivars was similar, but there were variations, arising probably from the physiological response to stress, such as aerenchyma formation in the root and increased pericycle in the rhizome of U. hybrida.

Highlights

Use of pastures is the most common and cheaper to create cattle in Brazil, either beef or dairy cattle
This study aimed to describe and compare individuals in different morphological stages of the death of pastures syndrome (DPS) development by identifying its impact on plant tissues of root, rhizome, and leaves of U. brizantha cv
Mulato II were collected from three farms with the occurrence of death of pastures syndrome (DPS) in the Southern Amazon, located to the extreme north of Mato Grosso

Summary

Introduction

Use of pastures is the most common and cheaper to create cattle in Brazil, either beef or dairy cattle. The maintenance of the forage productivity, combined with the climate and soil conditions needed for a sustainable system over time, constitutes one of the major livestock problems because the degradation of these ecosystems occurs on most of the farms. (Poaceae) arouse great interest among farmers because of their high dry matter production, as well as adaptability, persistence, ease of establishment, and a good nutritional value; these forages have reduced disposition to disease and present good growth during the entire year, during the rainy season (Costa et al, 2006). Rich.) R.D. Webster and U. decumbens (Stapf) R.D. Webster have been used for many years in tropical pastures in Brazil (Pereira et al, 2012)

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