Inheritance of pinacle exsertion in rice

Abstract

Incomplete panicle exsertion is one of the symptoms of cold injury at the reproductive stage of the rice plant (Oryza sativa L.), which damages grain yield and raises disease incidence. For this reason, panicle exsertion is a better indicator of cold tolerance under field conditions than spikelet sterility, which may also be affected by other climatic factors. This work studies the variability of degree of panicle exsertion in rice, under the Southern Brazilian environmental conditions and determines the inheritance and heritability of this trait. Four rice genotypes of different cool temperature reactions at the reproductive stage were crossed and field evaluated, with the F 2 generation, in relation to the degree of panicle exsertion and spikelet fertility. There was variability among the genotypes for panicle exsertion. The F 2 generation of the crosses presented continuous distribution and transgressive segregation towards incomplete exsertion, indicating that genes controlling this trait may be complementary distributed between the parents. Heritability was moderate, so selection for complete panicle exsertion should be applied in advanced generations. Key words: Oryza sativa L., chilling temperature, cold tolerance, complete panicle exsertion, heritability HERANÇA DA EXERÇÃO DA PANÍCULA EM ARROZ RESUMO: A exerção incompleta da panícula é um dos sintomas de dano por frio no estádio reprodutivo da planta de arroz (Oryza sativa L.), o qual prejudica o rendimento de grãos e aumenta a incidência de doenças. Devido a isso, a exerção da panícula é um bom indicador da tolerância ao frio sob condições de campo ao invés da esterilidade de espiguetas, que também pode ser afetada por outros fatores climáticos. Este trabalho objetivou estudar a variabilidade do grau de exerção da panícula de arroz sob as condições ambientais do sul do Brasil e determinar a herança e herdabilidade desta característica. Quatro genótipos de arroz com diferentes reações à temperatura baixa no período reprodutivo foram cruzados e avaliados a campo, juntamente com a geração F 2 , quanto ao grau de exerção da panícula e fertilidade de espiguetas. Houve variabilidade entre os genótipos para exerção da panícula. A geração F 2 apresentou distribuição contínua e segregação transgressiva na direção da exerção incompleta, indicando que os genes para exerção da panícula devem estar distribuídos complementarmente entre os genitores. A herdabilidade foi moderada, portanto seleção para exerção completa da panícula é recomendada em gerações avançadas. Palavras-chave: Oryza sativa L., temperatura baixa, tolerância ao frio, exerção completa da panícula, herdabilidade

Genetic analysis of mechanisms associated with inheritance of resistance to sheath rot of rice

“…High heritability estimates for PE corroborates with results reported by Sellammal, Robin, and Raveendran () and are, slightly, in contrast to Cruz, Milach, and Federizzi () and Girish et al. (), who reported moderate estimates of heritability.…”

Analysis of QTLs for panicle exsertion and its relationship with yield and yield-related traits in rice (Oryza sativa L.)

“…The diameter of the panicle neck is strongly correlated with the total sink capacity and grain weight, which are affected by the conductive tissue together with the source strength (Sasahara et al, 1999;Liu et al, 2008). Panicle neck length, known as 'panicle exsertion' (PE), is also considered to be essential for enhancing total sink capacity and grain filling by improving the transport efficiency of assimilates (Ma et al, 2002;da Cruz et al, 2008). Incomplete PE (also named sheathed panicle) is an adverse symptom observed in rice plants, which is associated with almost all cytoplasmic male sterile lines during the production of hybrid rice seeds (Shen et al, 1987).…”

“…Incomplete PE (also named sheathed panicle) is an adverse symptom observed in rice plants, which is associated with almost all cytoplasmic male sterile lines during the production of hybrid rice seeds (Shen et al, 1987). Sheathed panicles are usually found in rice germplasm or cultivar and can reduce grain yield and increase the incidence of disease (da Cruz et al, 2008). To improve PE of rice germplasms or varieties, it is necessary to understand its genetic control.…”

Efectos de la disminución de temperatura sobre el desarrollo de la pared de la antera y el grano de polen en Oryza sativa L.

“…Evaluaciones de campo indican que estos cultivares presentan distintos niveles de tolerancia al frío, expresada como porcentaje de granos vanos en la panícula o "vanazón", determinando que 'Zafiro-INIA' presenta menor esterilidad floral que 'Brillante-INIA' y éste menor que 'Diamante-INIA' (Alvarado et al 1997, Ortega 2007. El desarrollo reproductivo es sensible al estrés abiótico, no sólo en arroz, sino también en otras especies de cereales, como trigo y maíz (Saini &Westgate 2000, Cruz et al 2008.…”