Weight per Grain, Oil Concentration, and Solar Radiation Intercepted during Grain Filling in Black Hull and Striped Hull Sunflower Hybrids

Abstract

The effect of intercepted photosynthetically active radiation (PAR) on weight per grain and oil concentration and their dynamics was investigated in several sunflower (Helianthus annuus L.) striped and black hull hybrids grown in contrasting environments. The study included the previously investigated hybrids Dekalb G‐100 and NKT, and two near isohybrids, which differed in the character of the type of hull. The effect of intercepted PAR lower than those studied in previous works was also investigated. Oil concentration was affected by intercepted radiation but striped hull hybrids reached the maximum oil concentration at lower levels of intercepted PAR than black hull hybrids. A decrease in intercepted radiation decreased final oil concentration mainly due to a lower duration of the phase during which oil concentration linearly increases. Despite the hull type, changes in grain oil concentration that were originated by changes in intercepted radiation largely depended on kernel oil concentration. No differences were observed in the response of weight per grain to changes in intercepted radiation among black hull and striped hull hybrids. Low sensitivity of oil concentration to changes in intercepted PAR must be considered for modeling grain quality. Striped hull hybrids could perform as black hull hybrids in environments with low intercepted radiation during grain filling.

Variabilidad genotípica y ambiental del peso, tamaño y aceite del grano de girasol (Helianthus annuus L.) en el Noreste argentino.

“…Además, si ésta disminución ocurriera en la etapa inicial de llenado de grano afectaría el peso individual de los granos en los diferentes sectores del capítulo (Andrade y Ferreiro, 1997) decreciendo desde la periferia hacia el centro debido a una mayor oferta de nutrientes (Santalla et al, 2002). Por otro lado, a pesar que los híbridos estriados contienen menor proporción de embrión, el peso por grano de estos es mayor que los híbridos de tegumento negra (Izquierdo et al, 2008). El peso del embrión estuvo relacionado con la temperatura máxima en R1 a R5, el peso del grano y el porcentaje de aceite.…”

“…Línea punteada representa la relación 1:1. en grano (43 y 55 %) como en embrión (entre 53 y 66%) fueron similares a los valores anteriormente mencionados. De la Vega y Hall (2002) encontraron menores rendimientos de aceite en fechas tardías en comparaciones con siembras tempranas por menor radiación solar interceptada (Izquierdo et al, 2008) y menor duración del llenado de granos (Rondanini et al, 2006). Además, Izquierdo et al, (2008) afirmaron que una reducción de la radiación interceptada provoca disminución en el porcentaje de aceite tanto en híbridos de tegumento estriadas como negra, pero estos últimos son más sensibles a variaciones en la radiación.…”

“…La relación tegumento/embrión se estimó a partir de la proporción del embrión respecto al pericarpio. La proporción del embrión en el grano se calculó como PE/(PT + PE), donde PE y PT representan el peso del embrión y tegumento, respectivamente (Izquierdo et al, 2008).…”

Analysis and modelling of the factors controlling seed oil concentration in sunflower: a review

“…a decrease of the hull fraction) and for 1/3 to an increase of OC kernel (Connor and Hall, 1997;Lopez Pereira et al, 2000;Tang et al, 2006). OC increase would be related to the longer duration of active leaf area after flowering in more recent cultivars ("stay-green" character, De la Vega et al, 2011) rather than to a higher rate of oil accumulation (Izquierdo et al, 2008;Mantese et al, 2006). However, Vear et al (2003) who analyzed 30 years of breeding in the sunflower cultivars most grown in France did not conclude to a clear increase in OC contrastingly to grain yield improvement.…”

“…The black hull is mainly composed of lignin and cellulose with low protein (4%) and lipid (5%) content (Cancalon, 1971;Knowles, 1978). The kernel is composed of a coat, an endosperm, and the embryo where 95-97% of the achene oil is found with storage proteins (Izquierdo et al, 2008). Oil is extracted from the achene through crushing process after no or partial dehulling.…”