Remobilization of pre-anthesis assimilates to the grain for grain only anddual-purpose (Forage and grain) triticale

In Mediterranean environments, translocation of pre-anthesis assimilates to the grain is an important source of photosynthates. In this work, the effe ct of forage removal at the beginning of jointing on the amount of dry matt er (DM) accumulated before anthesis and remobilized during grain filling wa s studied in five spring and five winter triticale genotypes (xTriticosecal e Wittmack). Field experiments were conducted in 1992 and 1993 in northeast ern Spain. Two harvesting treatments were used: (i) grain production only a nd (ii) cutting the crop for forage at the beginning of jointing and harves ting the grain produced after regrowth. Pre-anthesis storage of carbohydrat es mas very important to grain filling in triticale, both for grain and for dual-purpose, Contribution of pre-anthesis assimilates to grain yield in t he uncut plots was 46% in spring triticale genotypes and 65% in winter geno types, as the later-maturity winter triticale genotypes mew more affected b y terminal abiotic stresses, Reductions in DM accumulated at anthesis after forage removal were more pronounced in winter genotypes (39%) than in spri ng genotypes (20%), where an earlier development allowed for a longer recov ery period after cutting; DR I reductions were similar to grain yield decre ases. The effect of forage removal on translocation depended on the growth habit of the genotype and environmental conditions. Most differences were a ssociated with changes in crop phenology, In spring types, with early joint ing, DM translocation and the contribution of pre-anthesis assimilates to g rain were not affected by forage removal, whereas both traits were drastica lly reduced in winter triticale. Most differences in C-13/C-12 carbon isoto pe discrimination (Delta) in grains were also phenology driven.