04056nab a2200289 i 4500003000900000005001700009008004100026040001800067072001400085100003100099100003800130100002600168100003400194100001900228100003600247100002700283245011700310500006400427520134500491520161501836650001303451650001403464650001303478650001303491773018503504856007703689BR-BrBNA20240502164334.0240502b2016    bl.mr|pooa||| 00| 0 eng |  aBR-BrBNAbeng  aF01b1930  aCunha, Ricardo Pereira da   aPedroso, Carlos Eduardo da Silva   aMittelmann, Andréa   aOliveira, Roberto Caetano de   aBohn, Alberto   aSilva, Jéssica Dias Gomes da   aMaia, Manoel de Souza   aRelationship between the morphogenesis of Italian ryegrass cv. ‘BRS Ponteio’ with forage and seed production  aPublicação on-line; 14 ref.; 3 illus; Sumaries (En, Pt)  a
ABSTRACT - 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 egative changes in the morphogenic characteristics and seed yielding.

Key words: Lolium multiflorum Lam., defoliation frequency, leaf expansion rate, leaf senescence rate, phenotypic.

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RESUMO - O presente estudo teve o objetivo de verificar, de forma precisa e detalhada, as respostas da cultivar de azevém anual ‘BRS Ponteio’, às diferentes frequências de desfolha para a produção de forragem e de sementes. Realizou-se, para tanto, um experimento com delineamento de blocos casualizados com quatro repetições. Foram aplicadas quatro frequências de desfolhas (sem, uma, duas e três) baseando-se no acúmulo térmico, onde se avaliou a taxa de aparecimento de folhas (TApF), o filocrono (F), a taxa de expansão de folhas (TEF), taxa de senescência de folhas (TScF), taxa de expansão dos colmos (TEC), taxa de perfilhamento (TP), duração de vida da folha (DVF), produção de forragem, proporção de lâminas foliares, colmos mais bainhas, material senescente e inflorescências em cada tratamento, bem como a produção de sementes. A segunda desfolha alterou marcadamente as respostas morfogênicas da planta, reduziu as taxas de expansão e aparecimento de folhas e aumentou as taxas de perfilhamento e de expansão do colmo. Esta plasticidade fenotípica manteve a alta produção de sementes da planta e propiciou a colheita de massa de forragem 100% superior à massa colhida no primeiro corte. A terceira desfolha ropiciou o aumento de 100% da massa de forragem colhida, todavia, promoveu alterações drásticas e negativas nas características morfogênicas e no rendimento de sementes.

Palavras-chave: Lolium multiflorum Lam., frequência de desfolha, taxa de expansão de folhas, taxa de senescência de folhas, fenotípico.  aAZEVÉM  aVARIEDADE  aDESFOLHA  aFORRAGEM0 02408dSanta Maria-RS Universidade Federal de Santa Maria - Centro de Ciências Rurais 1991o2024-1140tCiência Rural (Brazil)x0103-8478gv. 46(1) p. 53-59; (2016)wBR2024000874  uhttps://www.scielo.br/j/cr/a/FBJdKgQMVJrG8tz3VBhYBNS/?format=pdf&lang=en