Revista Árvore ISSN: 0100-6762 [email protected] Universidade Federal de Viçosa Brasil Bachin Mazzini-Guedes, Renata; Fernandes Lopes Pivetta, Kathia INITIAL GROWTH OF Bauhinia variegata TREES UNDER DIFFERENT COLORED SHADE NETS AND LIGHT CONDITIONS Revista Árvore, vol. 38, núm. 6, noviembre-diciembre, 2014, pp. 1133-1145 Universidade Federal de Viçosa Viçosa, Brasil Available in: http://www.redalyc.org/articulo.oa?id=48837807020 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Initial growth of Bauhinia variegata trees... 1133 INITIAL GROWTH OF Bauhinia variegata TREES UNDER DIFFERENT COLORED SHADE NETS AND LIGHT CONDITIONS1 Renata Bachin Mazzini-Guedes2 e Kathia Fernandes Lopes Pivetta3 ABSTRACT – Bauhinia variegata and B. variegata var. candida, commonly known as orchid trees, are small sized trees widely used for urban forestry and landscaping. Adult plants grow under full sun; in Brazil, however, seedlings are generally cultivated in commercial nurseries under natural half-shading. The objective of this study was to evaluate the influence of different colored shade nets and light conditions on the initial growth of B. variegata and B. variegata var. candida. The influence of six light conditions (red net with 50% shading; blue net with 50% shading; black net with 70% shading; black net with 50% shading; black net with 30% shading; and full sun) on the initial growth of B. variegata and B. variegata var. candida were evaluated along 160 days, and growth relationships were calculated. Seedlings showed more efficiency on the use of photoassimilated compounds when grown under full sun. Such condition is the most appropriate for seedling production of B. variegata and B. variegata var. candida, contradicting what has been performed in practice. Keywords: Orchid tree; Shading; Ornamental tree. CRESCIMENTO INICIAL DE MUDAS DE Bauhinia variegata SOB DIFERENTES TELAS COLORIDAS E CONDIÇÕES DE LUMINOSIDADE RESUMO – Bauhinia variegata e B. variegata var. candida, popularmente conhecidas como pata-de-vaca, são árvores de porte baixo muito usadas na arborização urbana e no paisagismo. Plantas adultas crescem sob sol pleno; no Brasil, no entanto, mudas são geralmente cultivadas em viveiros comerciais sob meia- sombra. O objetivo deste trabalho foi avaliar a influência de diferentes telas coloridas e condições de luminosidade no crescimento inicial de mudas de B. variegata e B. variegata var. candida. A influência de seis condições de luminosidade (tela vermelha com 50% de sombreamento, tela azul com 50% de sombreamento, tela preta com 70% de sombreamento, tela preta com 50% de sombreamento, tela preta com 30% de sombreamento e a sol pleno) no crescimento inicial das mudas foi avaliada ao longo de 160 dias, e relações de crescimento foram calculadas. As mudas foram mais eficientes no uso dos fotoassimilados quando cultivadas a sol pleno. Essa condição é a mais apropriada para a produção de mudas de B. variegata e B. variegata var. candida, contrariando o que vem sendo feito na prática. Keywords: Pata-de-vaca; Sombreamento; Árvore ornamental. 1 Recebido em 15.11.2013 aceito para publicação em 10.11.2014 2 Doutorado em Agronomia (Produção Vegetal), UNESP Univ Estadual Paulista 'Júlio de Mesquita Filho', Faculdade de Ciências Agrárias e Veterinárias (FCAV), Departamento de Produção Vegetal - Jaboticabal, SP - Brasil. E-mail: <[email protected]>. 3 UNESP Univ Estadual Paulista 'Júlio de Mesquita Filho', Faculdade de Ciências Agrárias e Veterinárias, FCAV, Departamento de Produção Vegetal, Jaboticabal, SP - Brasil. E-mail: <[email protected]>. Revista Árvore, Viçosa-MG, v.38, n.6, p.1133-1145, 2014 1134 MAZZINI-GUEDES, R.B. e PIVETTA, K.F.L. 1. INTRODUCTION usually avoid high light and temperature (LI; SYVERTSEN, 2006), what could be detrimental for sun- Bauhinia variegata L., belonging to the family sensitive seedlings. As studies on the light or shading Fabaceae and native to South China (MAK et al., 2008), influence on Bauhinia variegata and B. variegata is a small sized tree widely used for urban forestry var. candida growth were not found, the objective and landscaping. According to Aguiar and Figliolia of this study was to evaluate the influence of different (1996), it is probably the most used Bauhinia species colored nets and light conditions on the initial growth for ornamental purposes. It is a fast growing plant of those species. (MATHUR; MUKUNTHAKUMAR, 1992), reaching around 8 m height and 8 m crown diameter, that flowers 2. MATERIALS AND METHODS mainly from December to April (LAU et al., 2005), producing pink flowers of different tones (GLOBAL…, Mature brown seed pods, closed or partially open, 2003). B. variegata var. candida (Aiton) Voigt is also were harvested in September 2010 from 20 year old a small sized tree, reaching around 6 m height, that B. variegata and B. variegata var. candida trees flowers mainly from June to December (RORIZ, 2000) cultivated at the College of Agricultural and Veterinary and produces white flowers (MAK et al., 2008). Both Sciences of the State University of São Paulo (FCAV/ are commonly known as orchid trees and usually grow UNESP), located in the municipality of Jaboticabal, under full sun (RORIZ, 2000; GLOBAL…, 2003). Brazil (21°15’22" S and 48°18’58" W, at 590 m altitude). According to the Köppen classification, the climate The sunlight, according to its duration, intensity, regime in Jaboticabal is subtropical with dry winters and quality, is essential for plant growth and flower and humid summers (Cwa). The experiment was production (SHAHAK et al., 2004a). It affects several implemented at the Experimental Nursery of Ornamental physiological processes, such as photosynthesis, that and Forest Plants of the FCAV/UNESP. is primarily responsible for the accumulation of plant dry matter (BENINCASA, 2003). According to the species Immediately after harvesting, the seeds were cleaned and its habitat, a certain light amount can either limit and kept in paper bags at room temperature for about or optimize its development (MELEIRO; GRAZIANO, three months. Seeds were then sown in Plantmax ® 2007). substrate (Eucatex ) in December 2010 and, after 20 days, seedlings were transplanted to black plastic bags Black nets, that partially filter the sunlight, and of 2 L capacity that contained soil and cattle manure colored nets, that modify it, have been widely used (3:1, v:v). The soil, collected at 0.0-0.2m depth at the for agricultural purposes (SHAHAK et al., 2004a; campus area, was classified as Oxisol. Soil plus cattle MEIRELLES et al., 2007). They provide more shading manure analysis was performed according to Raij et for plants and, also, protection against wind, hail, pests, al. (2001) at the Laboratory of Soil Analysis of the FCAV/ and other extreme environmental conditions (LOBOS UNESP. As it was considered appropriate (data not et al., 2013). Furthermore, their application improves shown), there was no additional fertilization throughout the internal climatic conditions, increasing air humidity the experimental period. and reducing temperature (SHAHAK et al., 2004a,b; LOBOS et al., 2013). While black nets transmit a scattered In January 2011, seedlings were submitted to and uniform light, therefore maintaining light quality, different light conditions, which consisted of six colored ones modify both light quantity and quality treatments: red net with 50% shading (red net 50%), (OREN-SHAMIR et al., 2001). Blue nets, for instance, blue net with 50% shading (blue net 50%), black net transmit green and blue lights (400-540 nm) absorbing with 70% shading (black net 70%), black net with 50% the red light (550-660 nm), while red nets transmit light shading (black net 50%), black net with 30% shading (black net 30%), and full sun. The structure for each at 590 nm, i.e., the light spectrum region that is best treatment was built as a tunnel and measured 6.0 m absorbed by plants resulting, therefore, in higher length, 1.5 m width and 1.8 m height. The tunnels, photosynthesis rate (SHAHAK et al., 2004b). which were entirely coated with each net, were placed In Brazil, tree seedlings are generally cultivated, 2 m apart from each other, according to the sun east- for commercial purposes, under half-shading. Such west direction, so that there was no additional shading condition, promoted by either black or colored nets, that could influence plant growth. The average Revista Árvore, Viçosa-MG, v.38, n.6, p.1133-1145, 2014 Initial growth of Bauhinia variegata trees... 1135 photosynthetically active radiation (PAR) during the with the exception of the black net 30%, which, in turn, experimental period for each treatment was 54.0, 70.3, was statistically equal to both blue net 50% and full 38.7, 75.1, 104.7, and 143.8 W m-2 for the red net 50%, sun treatments. blue net 50%, black net 70%, black net 50%, black The influence of the treatments on stem length net 30%, and full sun, respectively. Average minimum, varied along the experimental period. However, at the mean, and maximum air temperature were, respectively, last evaluation (at 160 days), the black net 70% stood 17.4, 22.1, and 29.1 °C; average air humidity was 77.4%; out for promoting the longest stem length of the air temperature and humidity were monitored at the experiment, feature that was maintained from the previous experiment location. Irrigation was performed by a evaluation, performed at 120 days. These plants produced dripping system that remained on along four hours stems that were around 10 cm longer than plants grown in the afternoons, three times per week. Each pot had under the red net 50%, that presented the second highest an individual dripper that released 400 mL water during value (Table 1).