Persistence and productivity in nondormant alfalfa

Abstract

Mortality is substantial in alfalfa stands and may be due to random and natural selection. The effects of selection for persistence on single-plant yield are not well understood. This study examined relationships between yield, nonstructural carbohydrates (TNC), and other agronomic characteristics, and persistence in nondormant alfalfa. S₁ progenies were produced on 60 plants dug from a five-yr-old field of 'CUF-101' (Persistent population) in central AZ and 60 greenhouse-grown CUF-101 plants (Random population). Progenies were sown in a replicated field trial at Tucson, AZ in Oct. 1989. Spring and fall forage yield was significantly lower in the Persistent population than in the Random population. Rate of stem regrowth following harvest was also lower in the Persistent population. S₁ progenies from the Persistent population contained approximately 7.1% more TNC in roots and crowns than the Random population, suggesting that TNC and persistence may be positively correlated. These data suggest that plants in the Persistent population exhibited more conservative growth patterns and that a negative genetic correlation may exist between single-plant yield and persistence. Simultaneous selection for traits associated with productivity and persistence may be necessary.