Morphological characteristics and proportion of leaf blade tissues of elephant grass clones under sheep grazing

Bruno Leal Viana,Mário De Andrade Lira,Adriana Guim,Mércia Virgínia Ferreira Dos Santos,Alexandre Carneiro Leão De Mello,Márcio Vieira Da Cunha,José Carlos Batista Dubeux Júnior

doi:10.1590/s0100-204x2018001100009

Bruno Leal Viana, Mário De Andrade Lira + Show 5 more

Open Access

https://doi.org/10.1590/s0100-204x2018001100009

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Abstract

Abstract: The objective of this work was to characterize morphologically elephant grass (Pennisetum purpureum) genotypes and to estimate their proportions of leaf blade tissues under grazing. Two tall varieties (Elephant B and IRI-381) and three short ones (Mott, Taiwan A-146 2.37, and Taiwan A-146 2.114) were evaluated under intermittent sheep grazing as to the following morphological characteristics: plant height, internode length, and leaf blade/culm ratio. Moreover, the proportions of the following leaf blade tissues were estimated: sclerenchyma, adaxial and abaxial epidermis, bulliform cells, vascular bundles, phloem, vascular sheath, xylem, and mesophyll. The short varieties were 28.6% shorter than the tall ones and showed higher leaf blade/culm ratio; Mott and Taiwan A-146 2.114 had the shortest internodes of 3.9 and 4.7 cm, respectively, over ten grazing cycles. The clones differed regarding their proportions of leaf blade tissues, except for abaxial epidermis, phloem, and xylem. The differences in morphological characteristics indicate that the short clones Mott and Taiwan A-146 2.114 are better adapted to sheep grazing, and, therefore, may be recommended for the improvement of pastures.

Highlights

Elephant grass (Pennisetum purpureum Schumach.) has a high productive potential, which, combined with other favorable characteristics of this forage, such as quality, palatability, vigor, and persistence, has stimulated its breeding programs and cultivation
The pre-grazing means for the leaf blade/culm ratio (L/C) varied from 0.33 for IRI-381, in the second cycle, to 1.97 for Taiwan A-146 2.114, in the ninth cycle (Table 2)
Except in the eighth cycle, the L/C ratio differed among the five studied clones, with the short ones showing a larger proportion of leaf blades

Summary

Introduction

Elephant grass (Pennisetum purpureum Schumach.) has a high productive potential, which, combined with other favorable characteristics of this forage, such as quality, palatability, vigor, and persistence, has stimulated its breeding programs and cultivation. When used for pasture, the species may exhibit a limiting growth habit, with rapid elongation of internodes, which results in fast culm maturation (Veiga, 1994). This is problematic since shorter and tenderer plants, with a higher leaf blade/culm ratio, may be a more appropriate alternative for pastures, especially due to the greater ease of forage prehension by small ruminants. The increasing interest in the use of short clones in pasture systems is mainly attributed to their better prehension by animals and to the location of their apical meristems close to the ground, which reduces meristem decapitation and confers high persistence under grazing conditions (Resende et al, 2002; Silva et al, 2009; Viana et al, 2009; Araújo et al, 2011). There are few known reports on dwarf clones subjected to grazing by small ruminants (Viana et al, 2015)

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