Yield Components, Morphology, and Forage Quality of Multifoliolate Alfalfa Phenotypes
Forage quality of alfalfa (Medicago sativa L.) maybe improved by increasing the proportion of leaves to stems. Our objective was to examine the influence of the moltifoliolate leaf trait on morphology, yield components, and forage quality of alfalfa. Multifoliolate plants selected for production of five, seven, or nine leaflets per leaf were compared to trifoliolate plants selected for rapid (RSER) and slow (SSER)shoot elongation rate that also exhibited low and high leaf/stem ratios, respectively. Herbage from field-grown plants was sampled twice in each of two years. Leaves of multifoliolate plants averaged. 4.4, 6.2, and 6.8 leaflets per leaf for phenotypes FIVE, SEVEN, and NINE, respectively. In 1987 multifoliolate plants produced fewer shoots per plant (x̄ = 26) but phenotypes FIVE and SEVEN consistently produced larger shoots (x̄ = 2.0 g shoot−1) than the RSER phenotype(x̄ = 59 shoots plant−1, 1.3 g shoot−1. Leaf/stem ratio was lowest for phenotype RSER (0.63), while leaf/stem ratio of SSER (1.27) equalled that of phenotypes SEVEN (1.20) NINE (1.30). In vitro dry matter disappearance (IVDMD) of herbage of multifoliolate phenotypes and SSER was greater(P < 0.10) than that of phenotype RSER in 1986, while in 1987 IVDMD of herbage of phenotypes NINE and SSER exceeded that of RSER. Herbage N concentrations of multifoliolate plants were not consistently greater than that of phenotype RSER, and were associated with lower leaf N concentrations in multifoliolate plants. The multifoliolate plants used in this study had high leaf/stem ratios, but this trait was not consistently associated with improved forage quality. Environment,along with other plant characters, also influenced IVDMD and N concentrations of herbage of these plants.
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