Genetic and phenotypic characterization of Tinopiro (Thinopyrum intermedium) as a dual-purpose perennial crop in the Southern Cone

Doctoral thesis abstract

Resumo

Agriculture based on annual crops requires intensive input management, which has been associated with significant degradation of natural resources. The development of perennial grain crops such as intermediate wheatgrass - (Thinopyrum intermedium) may greatly contribute to reduce this problem, however, previous research has been carried out in high latitude environments and there is no information on this crop for temperate regions with mild winters. The aims of this thesis were a) to determine the cold requirements of intermediate wheatgrass, b) to evaluate the agronomic performance of intermediate wheatgrass managed as a dual-purpose crop in Uruguay, c) to understand the genetic architecture of grain and forage yield components in intermediate wheatgrass under dual-purpose management. Three experiments were carried out, the first one in growth chambers and the other two in the field during two years in Paysandú, Uruguay. Flowering percentage and most grain yield components increased as the length of the cold incubation period at 5°C and 10 h photoperiod increased from 3 to 7 weeks. High intra-population phenotypic diversity was estimated. The effects of two populations produced under contrasting environments and the effects of three doses of nitrogen on grain and forage yield under dual-purpose management were evaluated in the second experiment. The first year, both populations had similar flowering percentages of about 48%, which resulted in an average grain yield of 316 kg ha -1. The average forage yield for the first year was 14695 kg ha -1 and decreased to 4037 kg ha -1 the second year. Fertilization with 160 kg ha -1 nitrogen increased grain yield by 63% and forage yield by 28%. In the third experiment, grain yield components, forage and phenological traits were evaluated in 30 half-sib families. Most of the traits evaluated showed no genotype x age interaction. Indirect selection for spikes per plant and/or yield per spike could have a greater response to selection than direct selection for yield per plant. No trade-off was detected between grain yield components and aboveground biomass production. These results suggest that expansion of this species as a dual-purpose crop to temperate regions with mild winters is feasible after some cycles of selection.