Vegetative and reproductive development of Costa Rican weedy rice compared with commercial rice (Oryza sativa)

Abstract

-The variability in the chronology of the vegetative and reproductive development of weedy rice complex has been little studied. However, a field trial was established to study the timing of growth stages of sixteen weedy rice morphotypes and five rice varieties of Costa Rica. Weedy rice presented a wide range of variation for all descriptors among and within morphotypes. Weedy rice was taller than the rice varieties during vegetative phase and showed a growth increase of 14-23 cm every two weeks. Six morphotypes emerged earlier than commercial rice varieties, but no differences where found between samples for the time required for starting tillering. Early emergence of weedy rice morphotypes was not associated with early flowering, thus no correlation was detected between the vegetative and reproductive phases. All weedy rice morphotypes reached anthesis and maturity earlier than the rice varieties. Nevertheless, varieties Setesa-9 and CR-5272 overlapped anthesis with eleven morphotypes and variety CR-4338 overlapped flowering with eight weedy rice morphotypes. In contrast, none of the morphotypes overlapped anthesis with varieties CR-1821 and CR-1113. The results obtained showed the competitive capacity of weedy rice and provided valuable information about flowering overlap between weedy rice morphotypes and rice varieties which will be useful in the design of gene flow studies among them.Keywords: anthesis overlapping; growth stages; red rice; rice varieties. RESUMO -O desenvolvimento vegetativo e reprodutivo das diferentes variantes morfológicas do arroz-vermelho tem sido pouco estudado. Um ensaio de campo com dezesseis morfotipos de arroz-vermelho e cinco variedades comerciais de arroz da Costa Rica foi estabelecido com o fim de estudar o crescimento dessa planta daninha. Nos resultados, observou-se que o arroz-vermelho

Assessment of gene flow from a herbicide-resistant indica rice (Oryza sativa L.) to the Costa Rican weedy rice (Oryza sativa) in Tropical America: factors affecting hybridization rates and characterization of F1 hybrids

“…Nevertheless, the accessions that did not hybridize under field conditions are not genetically incompatible with PPT-R, as it was possible to obtain hybrids between them by manual crossing (Sanchez-Olguin 2005). The lack of outcrossing under the experimental conditions reflects the complexity of the hybridization process and the variability of Costa Rican weedy rice populations.…”

“…A comprehensive characterization of the Costa Rican weedy rice complex, including morphology (Arrieta-Espinoza et al 2005) and lifecycle (Sanchez-Olguin et al 2007), was carried out prior to this study. About 21 distinct morphotypes were identified; the majority of them grouped with cultivated rice varieties (sativalike) and others were more closely related to the wild species O. rufipogon Griffith (rufipogon-like).…”

Agronomic performance of F1, F2 and F3 hybrids between weedy rice and transgenic glufosinate‐resistant rice

“…Weedy rice tends to have vigorous vegetative growth, matures comparatively early, is easily shattered and has variable seed dormancy. All of these characteristics make the control of weedy rice very difficult in comparison with other weeds 9, 11, 15…”

Períodos de interferência de plantas daninhas na cultura do sorgo forrageiro em terras baixas

“…A opção pela rotação do arroz irrigado com as espécies ditas "de sequeiro" (milho, soja e sorgo), além de diversificar a produção de grãos nessas áreas, proporciona a possibilidade de rotação de princípios ativos e a redução da pressão de seleção de biótipos de plantas daninhas resistentes na cultura do arroz irrigado (Andres et al, 2007), contribuindo ainda para redução da presença de arroz-vermelho e capim-arroz no banco de sementes do solo pela adoção de métodos de controle eficientes, modificações das condições de solo e utilização de herbicidas seletivos para a cultura (Erasmo et al, 2004;SOSBAI, 2005;Sánchez-Olquín et al, 2007). Além disso, o sorgo apresenta maior tolerância ao encharcamento que o milho e a soja e se adapta com certa facilidade às condições de várzeas, com menores prejuízos, por suportar o encharcamento do solo por períodos maiores que o milho e a soja (Raupp, 2000;Chielle et al, 2000).…”