Effects of different water regimes on the anatomical characteristics of roots of grasses promising for revegetation of areas surrounding hydroelectric reservoir

Abstract

The objective of this study was to evaluate the effect of different water regimes on some aspects of root anatomy of three grasses: Echinochloa pyramidalis (canarana), Setaria anceps (setária) and Paspalum paniculatum (paspalo). The plants were cultivated in a greenhouse and submitted to three water regimes: daily watering; suspension of watering and suspension of watering followed by submersion of the root system. Segments of the middle part of the roots were taken and submitted to classical techniques in botany for slide making and tissue analysis. Anatomical differences were observed among the three grasses submitted to water regimes regarding the number of cell layers in the external cortex and thickening of lignin and suberin. The submerged roots of the three species presented an increasing tendency in the proportion of the area of the cortex destined for the aerenchyma besides thickening of the endodermis and the cells of the medullar parenchyma. The aerenchyma presence in the three water regimes suggested it is a characteristic of these species. The adaptations developed by these species contributed to the understanding of their occurrence in areas that are subject to drought periods and successive floods. INDEX TERMS:Revegetation, grasses, water deficit, Echinochloa pyramidalis, Setaria anceps, Paspalum paniculatum, flood, aerenchyma, anatomical characteristics, roots. EFEITOS DE DIFERENTES REGIMES HÍDRICOS SOBRE AS CARACTERÍSTICAS ANATÔMICAS DE RAÍZES DE GRAMÍNEAS PROMISSORAS PARA REVEGETAÇÃO DE ÁREAS MARGINAIS A RESERVATÓRIOS HIDRELÉTRICOSRESUMO Conduziu-se o presente trabalho objetivavando-se avaliar o efeito de diferentes regimes hídricos sobre alguns aspectos da anatomia da raiz das seguintes gramíneas: Echinochloa pyramidalis (canarana), Setaria anceps (setária) e Paspalum paniculatum (paspalo). As plantas foram cultivadas em casa-de-vegetação e submetidas a três regimes hídricos: regas diárias; suspensão da rega e suspensão da rega seguida de submersão do sistema radicular. Foram retirados segmentos da parte mediana das raízes, os quais foram submetidos a técni-cas clássicas em botânica para confecção de lâminas e análise de tecidos. Foram observadas diferenças anatô-micas nas três espécies de gramíneas submetidas aos três regimes hídricos com relação ao número de camadas de células do córtex externo e o espessamento de lignina e/ou suberina. As raízes em submersão nas três espécies apresentaram uma tendência de aumento na proporção da área do córtex destinada a aerênquimas, além de um espessamento tanto da endoderme como das células do parênquima medular. Pela presença de aerên-quimas nas três espécies sujeitas aos três regimes hídri-cos, infere-se que esses são constitutivos. As adaptações desenvolvidas por essas espécies contribuíram na compreensão da ocorrência dessas em áreas que passam por períodos de seca e inundações sucessivas.

Root and stem anatomy and histochemistry of four grasses from the Jianghan Floodplain along the Yangtze River, China

“…Root structures found herein for all four species, including P. distichum, are similar to those reported for P. dilatatum by Fabbri et al (2005), Mollard et al (2008), and Vasellati et al (2001) and P. paniculatum (Da Silva et al, 2003), except that our histochemical studies have demonstrated Casparian walls, suberin lamellae, and lignified secondary cell walls in the mostly biseriate exodermis. The exodermal Casparian material in roots is similar to that found for Typha glauca and T. angustifolia by Seago et al (1999), except that Typha exodermis is multiseriate, and the Y-shaped Casparian material is similar to that found in Glyceria maxima by Soukup et al (2007).…”

“…Hubbard, and Paspalum distichum L.) in particular with regard to roots, rhizomes, and stolons (sensu Bell, 2008). Culms and leaves of such grasses have been studied more in detail (Buitenhaus and Veldkamp, 2001;Da Silva et al, 2003;Deshpande and Sarkar, 1961;Fabbri et al, 2005;Hanna et al, 1976;Metcalfe, 1960;Soper, 1956;Vasellati et al, 2001). Accordingly, we focus herein on anatomical features of roots, rhizomes, and/or stolons of these four plants, as they occur in nonflooded conditions that enable the species to be adaptable to their amphibious life styles.…”

Anatomical adaptations of Astragalus gombiformis Pomel. under drought stress

“…Leaf tissues exposed to drought shows various responses. Thus, in many species such as, Ctenanthe setosa and Triticum aestivum, the entire lamina and mesophyll thickness were reduced under drought stress [2][3][4][5][6][7][8][9][10][11][12][13][14], while it was unaffected by water stress in salvia spendens and Glycine max [13][14][15][16]. Bussotti et al [17] found that limited soil moisture caused a major thickening of the mesophyll, especially in the leaf cuticle and spongy parenchyma of the beech plant, Fagus sylvatica.…”

Anatomical root variations in response to water deficit: wild and domesticated common bean (Phaseolus vulgaris L)

“…However, protoderm and cortex thickness were affected only in the drought sensitive maize (Peña-Valdivia et al, 2005). Some of the above root anatomical responses seem to be adaptations that enhance plant survival in hostile environments (Da Silva et al, 2003).…”