Crossing Contamination along Contiguous Borders of Certified Alfalfa Seed Fields¹

Abstract

Multiple pest resistant alfalfa (Medicago sativa L.) cultivars in commercial production were used to study cross‐pollination along contiguous borders using contrasting levels of disease and insect resistance. Twenty‐eight seed samples were obtained from each of 3 cultivars and 26 from the fourth cultivar. In 110 sample comparisons with foundation and certified lots, only five departures from expected levels of resistance were found. Departures appeared to be random in relation to distance from foreign pollen source and leafcutter bee, Megachile rotundata (F.), locations and were interpreted as sampling variations. Thus the data indicated that isolation requirements for production of certified seed in fields larger than 2 ha using M. rotundata (F.) as pollinators could be less stringent than current standards without sacrificing the integrity of the cultivar.

Genetic Markers and Plant Genetic Resource Management

“…But a dominant allele, conferring scab resistance, served to measure pollen flow in a monoecious, inbred line of Cucumis sativus L. (Wehner and Jenkins 1985); and resistance to spotted alfalfa aphid [(Therioaphis maculata (Buckton)] documented minimum isolation distances and border effects in two commercial cultivars of Medicago sativa L. (Brown et al 1980(Brown et al , 1981.…”

Genetic Markers and Plant Genetic Resource Management

“…Monitoring germplasm's trueness-to-type with markers affecting insect and disease resistance (and with some morphological traits) may be limited by difficulties in accurately and reproducibly measuring gene expression. But a dominant allele, conferring scab resistance, served to measure pollen flow in a monoecious, inbred line of Cucumis sativus L. (Wehner and Jenkins 1985); and resistance to spotted alfalfa aphid [(Therioaphis maculata (Buckton)] documented minimum isolation distances and border effects in two commercial cultivars of Medicago sativa L. (Brown et al 1980(Brown et al , 1981. c. Isozymes, Seed Proteins, and DNA Markers.…”