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.

No abstract

The effects of radiation conditions and nitrogen (N) availability on triticale were investigated. The relationship between shading (S) and N supply and their effect on the industrial use of triticale flour were studied. Incident radiation/shade conditions affected all the parameters measured. Nitrogen supply influenced yield, protein content, sodium dodecyl sulphate-sedimentation index (SDS-SI), alkaline water retention capacity (AWRC), cookie factor and diameter of four cookies (D4C). The proportion of proteins of high molecular weight was increased with nitrogen supply and pre-anthesis shade, while post-anthesis shade increased proteins of lower molecular weight. The interaction between variety and N supply was significant for yield, SDS-SI and AWRC. Only yield and specific weight were affected by N × S interaction. Significant effects of the interaction of variety, N supply and shade conditions were observed for specific weight. I N T RO D U C T I O NTriticale (× Triticosecale Wittmack) is a hybrid (wheat × rye) that has proved to be a suitable alternative crop in areas where soil conditions restrict wheat production. Triticale flours have been found to be more suitable for the manufacture of products like cookies, that may be prepared with a gluten of lower tenacity than that needed in bread manufacture (Rubiolo et al., 1998). Dough properties and baking performance of wheat are determined by the structure and quantity of gluten proteins and are strongly dependent on both the genotype and the growing conditions. Different levels of nitrogen (N) fertilization are known to cause changes in flour protein quantities and proportions. Obtaining simultaneous improvement in grain yield and grain protein content from breeding is considered to be difficult because of the negative association usually found between these traits (Slafer, 1994). A successful increase in triticale crop usage will depend on the ability to use marginal regions coupled with good grain quality. Triticale genotype and environmental factors have been found to be important in cookie quality (Aguirre et al., 2002). Falling number depends mainly on the amount of rain during the grain-filling period (Aguirre et al., 1993). These factors affect the †