Influence of planting angle on the shooting and rooting of cuttings of Phyllanthus sellowianus (Klotzsch) M\ufcll. Arg.

A estabiliza\ue7\ue3o de encostas naturais ou artificiais de terrenos e margens de cursos de \ue1gua \ue9 poss\uedvel com a aplica\ue7\ue3o de t\ue9cnicas propostas pela engenharia natural ou bioengenharia de solos, que utilizam a vegeta\ue7\ue3o, sozinha ou combinada com materiais inertes. Para isso, a vegeta\ue7\ue3o a ser empregada necessita preencher alguns requisitos relacionados a aspectos ecol\uf3gicos, fitossociol\uf3gicos e de reprodu\ue7\ue3o. As t\ue9cnicas de engenharia natural utilizam as plantas em diferentes posi\ue7\uf5es em rela\ue7\ue3o \ue0 horizontal. Por essa raz\ue3o, o presente trabalho tem por objetivo avaliar os efeitos de diferentes \ue2ngulos de plantio de estacas de Phyllanthus sellowianus (Klotzsch) M\ufcll. Arg. para a estabiliza\ue7\ue3o de taludes. Com isso, ser\ue1 poss\uedvel sugerir a forma mais adequada para o plantio dessa esp\ue9cie, ou seja, em quais pr\ue1ticas biot\ue9cnicas esta pode ser melhor utilizada. O experimento foi conduzido no Viveiro Florestal, na Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, no per\uedodo de agosto a novembro de 2007. Os tratamentos consistiram no plantio de estacas de Phyllanthus sellowianus (Klotzsch) M\ufcll. Arg., em tr\ueas \ue2ngulos diferentes (10\ub0, 30\ub0 e 90\ub0). As estacas foram coletadas na regi\ue3o central do estado do RS e confeccionadas com 30 cm de comprimento (\ub1 1 cm de varia\ue7\ue3o), com di\ue2metro m\ue9dio de 1,9 cm. Dois ter\ue7os de sua base foram inseridos em substrato inerte (areia). O delineamento experimental foi o inteiramente casualizado, com trinta repeti\ue7\uf5es (estacas) por tratamento. Ap\uf3s 90 dias foram analisados as seguintes caracter\uedsticas: sobreviv\ueancia das estacas, n\ufamero, comprimento e di\ue2metro dos brotos e ra\uedzes prim\ue1rias, al\ue9m da massa seca das ra\uedzes e brotos. A esp\ue9cie apresentou altos valores de sobreviv\ueancia, com tend\ueancia de maiores resultados em estacas plantadas em \ue2ngulos de 10\ub0 e 90\ub0. O plantio de estacas em \ue2ngulo de 90\ub0 tamb\ue9m proporcionou os maiores valores da soma de comprimento e da massa seca dos brotos, enquanto que o di\ue2metro e o n\ufamero de brotos n\ue3o apresentaram diferen\ue7as significativas entre os \ue2ngulos de plantio. O n\ufamero, a soma do comprimento e a massa seca das ra\uedzes, tiveram valores significativamente maiores em estacas plantadas em \ue2ngulo de 90\ub0. O di\ue2metro da raiz mais longa apresentou maior m\ue9dia em estacas plantadas em \ue2ngulo de 10\ub0, enquanto que o valor m\ue9dio do comprimento da raiz mais longa por estaca n\ue3o mostrou diferen\ue7a estat\uedstica entre os tr\ueas \ue2ngulos de plantio.The stabilization of natural or artificial slopes of land and shores of water courses is possible with the application of some techniques, proposed by natural engineers and soil bioengineers, which use vegetation alone or in combination with inert materials. For this reason, the vegetation to be employed needs to meet some requirements related to ecological, phytosociological and reproduction aspects. Techniques of natural engineering use plants in different positions in relation to the horizontal line. Thus, this study aims to evaluate the effects of different planting angles of cuttings of Phyllanthus sellowianus (Klotzsch) M\ufcll. Arg. on slope stabilization. With these results the most appropriate form of planting this species can be proposed, ie, in which biotechnical practices it can be best used. The experiment was carried out at the Forest Nursery, at the Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul. The study was done from August to November of 2007. Treatments consisted of planting cuttings of Phyllanthus sellowianus (Klotzsch) M\ufcll. Arg. at three different angles (10\ub0, 30\ub0 and 90\ub0). Cuttings were 30 cm long (\ub1 1 cm of variation), with an average diameter of 1.9 cm, and were collected in the central region of the state of RS. Two-thirds of their base were inserted into inert substrate (sand). The experimental design was completely randomized, with 30 repetitions (cuttings) for each treatment. After 90 days, the following features were analyzed: cutting survival, number, length and diameter of shoots and primary roots besides the dry mass of roots and shoots. The species had high values of survival, with a tendency for very positive results for stem cuttings planted at angles of 10\ub0 and 90\ub0. Planting at an angle of 90\uba also provided the highest values of the sum of the length and dry mass of shoots, while the diameter and number of shoots showed no significant differences between the angles of planting. The number, the sum of the length and dry mass of roots were significantly higher in cuttings planted at a 90\ub0 angle. The diameter of the longest root presented the highest average in cuttings planted at a 10\ub0 angle, while the average length of the longest root per cutting was not statistically different between the three angles of planting