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Difficulties associated with producing high quality forage on salt affected soils is often associated with the inability of plants to establish and persist at elevated soil salinity levels. The cultivar NewHy RS‐wheatgrass is recommended for use on range sites with moderate salinity problems that receive at least 35 cm of annual precipitation. Objectives of this study were to evaluate (i) the ability to improve plant persistence in NewHy over three cycles of greenhouse selection at increased salinity levels and (ii) corresponding changes in seedling vigor and germination under nonsaline conditions. Greenhouse grown plants were irrigated every 3 d with a complete nutrient solution and salt levels were increased by an electrical conductivity (EC) of 6 dS m−1every 1 to 2 wk until an EC level of 42 dS m−1was reached and maintained until plant mortality occurred in 2002 and 2003. Probit analysis was used to estimate the time and salt concentration required to kill 50% of the plants (LD50) in each cycle. Significant differences for LD50were found among the different cycles of NewHy selected for persistence under saline conditions and the quackgrass [Elytrigia repens(L.) Nevski] parent with a resulting ranking of Cycle‐3 > Cycle‐2 > Cycle‐1 > quackgrass > NewHy (Cycle‐0). The largest single gain was achieved from NewHy Cycle‐0 to Cycle‐1, which required an additional 145 ECdays to reach an LD50level. Smaller increases were observed between Cycles‐1 and ‐2 and between Cycles‐2 and ‐3. Selection for persistence under a saline environment did not reduce seedling germination rate or vigor.

Four B111hybrids (2n= 9x= 63, ABDStStYYWW) were obtained between wheat (Triticum aestivumL., 2n = 6x = 42, AABBDD) and a diplosporic and 2n‐pollen‐producing Elymus rectisetus(2n= 6x42, StStYYWW) accession. We determined whether apomeiosis and 2npollen formation, which occur in the male parent, also occur in the Bill hybrids. Pistils were cleared for UV microscopy of callose and recleared for cytological observations using interference contrast microscopy. Callose fluorescence from most megaspore mother cells (MMCs) was typical of sexual species. These were classified as sexual. Abnormally elongated MMCs with walls devoid of callose were observed in 4.7% of pistils collected at meiotic prophase. These traits are typical of many apomeiotic MMCs in E. rectisetus. Asynapsis followed by mitosis in pollen mother cells (PMCs) consistently preceded unreduced pollen formation in E. rectisetus. This was not observed in the B11lhybrids, though the following meiotic anomalies were observed: (i) asynapsis, aggregation of chromosomes to several poles, and multiple divisions to form four to eight unbalanced microspores, and (ii) incomplete synapsis, formation of anaphase I laggards, and a second division resulting in four unbalanced microspores with micronuclei. The wheat haplome enforced PMC meiotic pairing (albeit abnormal) among homologous E. rectisetuschromosomes and generally inhibited apomeiosis, also by enforcing meiosis. Diplospory may be caused by the expression of embryo sac signals from one genome precociously expressed with megasporogenesis signals from another. If this is correct, the successful induction of apomixis in wheat may require the transfer of alien gene cassettes that confer appropriate degrees of reproductive asynchrony.

Callose, a β‐l,3‐glucan, is synthesized and deposited in the walls of megaspore mother cells (MMCs) of angiosperms that produce either normal monosporic (>90% of all angiosperm species) or bisporic embryo sacs. Such deposits are absent in angiosperms that produce tetrasporic embryo sacs and were recently shown to be absent in diplosporous Elymus rectisetus(Nees in Lehm.) A. Löve & Connor, TripsacumL. spp., and Poa nemoralisL. We determined the extent of callose deposits in MMCs of diplosporous weeping lovegrass (Eragrostis curvulaSchrad.), several additional diplosporous Tripsacumaccessions and aposporous buffelgrass (Pennisetum ciliare(L.) Link), Kentucky bluegrass (Poa pratensisL.), and Pennisetum squamulatumFresen. Callose deposition was studied in pistils cleared in an aqueous aniline blue clearing medium and observed by means of UV microscopy. Pistils cleared with conventional clearing media were studied by means of interference contrast microscopy. Some pistils were cleared and analyzed in one clearing medium and recleared and reanalyzed in the other. A callosic MMC was observed in only one of 376 appropriately staged pistils taken from diplosporous species. This pistil, one of 89 weeping lovegrass pistils studied, was probably facultatively sexual. An absence of callose during megasporogenesis may be characteristic of most types of diplospory. Though present, the distributions and quantities of callose observed in MMC walls of aposporous apomicts were erratically reduced, possibly as a result of early MMC abortion or early activation of nucellar initials. Callose deficiencies and vacuolization patterns support the following hypotheses: (i) apospory is caused by a moderately precocious gametophytization of nucellar cells, and (ii) bispory, tetraspory, and diplospory are caused by a moderately to extremely precocious gametophytization of the MMC that is nearly complete in the latter case and variably incomplete in the former two cases. Understanding how these precocious gametophytizations evolved and are regulated may be crucial to the eventual transfer of apomixis to major crop species and to its successful manipulation by breeders.