Relationship between the morphogenesis of Italian ryegrass cv. 'BRS Ponteio' with forage and seed production/Relacao entre as caracteristicas morfogenicas do azevem anual cv. 'BRS Ponteio' com a producao de forragem e de sementes

• Published in: Ciência rural p. 53
• Main Authors: da Cunha, Ricardo Pereira, Pedroso, Carlos Eduardo da Silva, Mittelmann, Andrea, de Oliveira, Roberto Caetano, Bohn, Alberto, da Silva, Jessica Dias Gomes, Maia, Manoel de Souza
• Format: Journal Article
• Language: Spanish
• Published: Universidade Federal de Santa Maria 01.01.2016
• Subjects: Brasil
• ISSN: 0103-8478; 1678-4596
• DOI: 10.1590/0103-8478cr20150296

This study aims to verify, accurate and precisely, the responses of Italian ryegrass 'BRS Ponteio' cultivar to different frequencies of defoliation for forage production and especially for seed production. For this purpose, a randomized block design experiment with four replications was conducted. Four frequencies of defoliation were applied (zero, one, two, and three) based on the thermal sum, evaluating the rate of leaf appearance (LAR), phyllochron (P), leaf expansion rate (LER), leaf senescence rate (LSR), stems expansion rate (SER), tillering rate (TR), leaf life span (LL), forage production, proportion of leaf blades, stems plus sheaths, senescent material, and inflorescences, as well as seed production. Second defoliation noticeably altered the morphogenic plant responses, reduced expansion rates and leaf appearance, increased rates of tillering and stems expansion. This phenotypic maintained a high seed production and provided a harvest of forage mass 100% higher than the collected mass in the first cutting. Third defoliation led to an increase of 100% of the harvested forage mass; however, it caused drastic and negative changes in the morphogenic characteristics and seed yielding. Key words: Lolium multiflorum Lam., defoliation frequency, leaf expansion rate, leaf senescence rate, phenotypic. O presente estudo teve o objetivo de verificar, de forma precisa e detalhada, as respostas da cultivar de azevem anual 'BRS Ponteio', as diferentes frequencias de desfolha para a producao de forragem e de sementes. Realizou-se, para tanto, um experimento com delineamento de blocos casualizados com quatro repeticoes. Foram aplicadas quatro frequencias de desfolhas (sem, uma, duas e tres) baseando-se no acumulo termico, onde se avaliou a taxa de aparecimento de folhas (TApF), o filocrono (F), a taxa de expansao de folhas (TEF), taxa de senescencia de folhas (TScF), taxa de expansao dos colmos (TEC), taxa de perfilhamento (TP), duracao de vida da folha (DVF), producao de forragem, proporcao de laminas foliares, colmos mais bainhas, material senescente e inflorescencias em cada tratamento, bem como a producao de sementes. A segunda desfolha alterou marcadamente as respostas morfogenicas da planta, reduziu as taxas de expansao e aparecimento de folhas e aumentou as taxas de perfilhamento e de expansao do colmo. Esta plasticidade fenotipica manteve a alta producao de sementes da planta e propiciou a colheita de massa de forragem 100% superior a massa colhida no primeiro corte. A terceira desfolha propiciou o aumento de 100% da massa de forragem colhida, todavia, promoveu alteracoes drasticas e negativas nas caracteristicas morfogenicas e no rendimento de sementes. Palavras-chave: Lolium multiflorum Lam., frequencia de desfolha, taxa de expansao de folhas, taxa de senescencia de folhas, fenotipico.