Wild proso millet (Panicum miliaceum L.) biotypes: growth analysis, competitive ability, and genetic variation

Abstract

Greenhouse and laboratory experiments were conducted with three domestic and nine wild proso millet (Pamicum miliaceum L.) biotypes. Growth during 70 days after planting was evaluated using the Richards function, which characterized relative differences in growth. Significant differences in shoot dry weight and leaf area expansion were observed for proso millet biotypes. The average shoot dry weight RGR was 0.095 g g-1 day-1. AGR of shoot dry weight ranged from 0.24 to 0.45 g day-1. Proso millet biotypes significantly differed in leaf area 26 DAP. Shoot dry weight and leaf area RGR did not differ among biotypes while differences were observed for AGR. Proso millet biotypes did not differ for specific leaf area although differences were detected for leaf area ratios. Domestic biotypes were shorter than wild biotypes. Tiller number varied from 2 to 4 per plant. Plant biomass partitioning results indicate different pattern of dry weight accumulation. Reproductive development started between the third and fourth week after planting, depending on biotype. Seed germination ranged from 28 to 100% 14 days after incubation. Seed coat as a percent of total seed biomass varied between 12.2 and 29.8%. Black seeded biotypes had different germination rates that ranged from 17 to 91% but no differences were observed for seed coat percent and seed weight. Shoot dry weight, leaf area, and biomass partitioning early growth differed among biotypes. The competitive ability detected between Canada-Rosemount black seeded and Colorado-Weld County tan seeded biotypes suggests a greater competitive ability for the Canada biotype. The genetic variation based on AFLP technique detected two distinct groups: (i) all domestic biotypes with black and olive seeded wild biotypes and (ii) tan seeded biotypes with a Wyoming brown seeded wild biotype. The genetic diversity observed among biotypes may correlate with differences in growth and competitive ability observed in these experiments. Although the molecular biology DNA research was conducted last in this thesis, future research of this type should begin with DNA assessment to detect the most diverse domestic and wild biotypes. This would allow for more focused research on growth analysis and competition studies.