Large portions of the world's arable acreage experience water stress on a regular basis. Improving crop productivity in such drought‐prone environments is a critical breeding objective. The goal of this study was to detect quantitative trait loci (QTL) associated with alfalfa (Medicago sativa L.) forage productivity during drought stress. Two first‐generation backcross (BC1) mapping populations (n = 253) derived from a cross between M. sativa subsp. sativa and M. sativa subsp. falcata were used to develop an updated tetraploid (2n = 4x = 32) genetic linkage map constructed from 600 single‐dose allele molecular markers. Map lengths associated with the two populations were 1293 and 1049 cM, with an average marker density of 3.8 and 3.9 cM, respectively. Half‐sib families derived from 206 BC1 individuals were evaluated for forage yield in seeded plots in seven water‐stressed environments in New Mexico and Oklahoma, USA. Significant genotype effects were detected within each population and environment. Interval mapping analysis identified 10 and 15 QTL that, respectively, improved or reduced forage yield during drought. Average phenotypic effects of each QTL on biomass yield ranged from 3 to 6% and the direction of these effects were generally consistent over environments. Desirable alleles identified in these parents may be suitable for marker‐aided introgression into elite populations to incrementally improve their forage productivity in water‐limited environments.

Characterization of genetic parameters in plant germplasm repository populations can facilitate their utilization in commercial breeding programs. This study investigated genetic combining abilities and heterosis for forage yield among diallel hybrids derived from nine previously selected high‐yielding accessions of the USDA‐ARS National Plant Germplasm System core collection of alfalfa (Medicago sativa subsp. sativa L.). These accessions originated from Turkey, South Africa, Greece, Afghanistan, Israel, Uzbekistan, Mexico, Morocco, and the USA. Forage yield response of the parents and their hybrids was determined near Las Cruces, New Mexico. General combining ability (GCA) and specific combining ability (SCA) effects were significant. The magnitudes of the GCA effects were about 5% (<0.71 Mg ha−1) relative to the mean yield of the parents (15.4 Mg ha−1). The Turkey, Afghanistan, and Uzbekistan accessions demonstrated significant positive GCA effects. Accessions from Greece and Morocco demonstrated negative GCA effects. Six hybrids outperformed the average of six commercial cultivars. Five of these six hybrids demonstrated positive SCA effects. Midparent heterosis ranged from –17 to 17%. The results indicate that crossing between alfalfa populations possessing high per se performance and different fall regrowth responses is likely to produce a higher proportion of high‐yielding hybrids in environments experiencing intermittent subfreezing winter conditions.

When considering the effects of various aspects of disabling conditions on the life satisfaction of individuals who have suffered a TBI, restriction of participation in life activities was found to have the greatest impact. Although the model accounted for a significant percentage in the variation of life satisfaction, a large proportion of the predictive picture (>82%) remains unclear. Doubtless, other variables impinge on life satisfaction that would further clarify the complex relationship between disabling conditions and life satisfaction in TBI.