The success of barley (Hordeum vulgare L.) cell and tissue culture research depends upon reliable callus culture and plant regeneration procedures. The objective of this study was to identify callus‐inducible genotypes, to evaluate media for effectiveness in promoting callus growth, and to identify genotypes capable of regenerating plants. Ninety‐one barley genotypes were evaluated for initiation and maintenance of callus growth. Forty‐five of the genotypes initiated callus, while 46 did not. Callus cultures were maintained by subculturing onto fresh media at monthly intervals. Genotypic variation was noted for longevity and rate of growth of callus cultures. Calli of several genotypes were maintained for more than 2 years. Murashige and Skoog's (MS) media promoted more callus initiation and provided better callus maintenance than media of Blaydes (B), Gamborg et al. (B5), Norstog (N), and Shenk and Hildebrandt (SH). Frequencies of callus initiation were high when either 0.5, 1.0, or 2.0 mg/L of 2,4‐D (2,4‐dichlorophenoxyacetic acid) were added to the media. There were significant genotype ✕ media interactions for callus initiation. Established calli were transferred to differentiation media to promote plant regeneration. Although there were genotypic differences in regeneration, the overall frequency was low (15%). Seventy percent of the regenerated plants were from calli of the cv. Akka and Wisconsin experimental selection X2387‐3.

Growth analysis of crambe (Crambe abyssinica Hochst. ex R. E. Fries) is important for the use of proper production practices and adequate pest management strategies. This study evaluated the heat unit requirements and quantitative characteristics of crambe growth [leaf area index (LAI), leaf area duration (LAD), yield, and total biomass] and the impact of defoliation on yield using artificial infestation with diamondback moth (Plutella xylostella L.) (DBM) in 1993 and 1994 and manual defoliation in 1995. The heat unit accumulation from planting to physiological maturity was approximately 1350 degree-days (DD) above 2.5 °C. The maximum LAI and generally the maximum daily increase of biomass occurred at the onset of flowering. The yield was proportional to LAD: 238 g m~2 versus 1187 DD in 1993, 190 g m~2 versus 1010 DD in 1994, and 117 g m~2 versus 774 DD in 1995. No reduction in yield or thousand seed weight was observed in any of the infestation or defoliation experiments. The artificial defoliation experiment showed that crambe can withstand substantial injury after the start of anthesis (25-50% of leaf area lost) without a significant yield loss.

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Bird depredation is a major concern of sunflower (Helianthus annuus L.) producers wherever the crop is grown in the world. Development of bird‐resistant varieties would provide an economical, environmentally safe method of contending with the problem. Morphological traits that confer resistance to depredation by birds have been identified. These traits include long involucral bracts, horizontally oriented heads, concave heads, and long head‐to‐stem distances. The objective of this study was to determine the stability of the traits when cultured in different environments. Breeding lines BRS1, ND208, ND492, ND495, ND162, and ND223‐16, which possess resistance traits, and seven susceptible counterparts, ND221, ND224, ND505, HA89, ND581, ND223‐1, and ND223‐3, were grown at three locations in North Dakota in 1988 and 1989. Measurements of the traits were made at the R7 stage of development. Genotype, environment, and genotype ✕ environment effects were all significant (P < 0.05). The genotype ✕ environment interaction effects, however, were not the result of changes in rank between resistant and susceptible genotypes, but represented differences in magnitude of response in the genotypes when grown in diverse environments. Results of this study indicate that performance of hybrids possessing these traits can be expected to be stable across a wide geographical area.

In vitro DNA:DNA hybridizations and hydroxyapatite thermal-elution chromatography were employed to identify the diploid wheat species ancestral to the B genome of Triticum turgidum. 3H-T. turgidum DNA was hybridized to the unlabeled DNAs of T. urartu, T. speltoides, T. sharonensis, T. bicorne, T. longissimum, and T. searsii. 3H-Labeled DNAs of T. monococcum and a synthetic tetraploid AADD were hybridized with unlabeled DNAs of T. urartu and T. searsii to determine the relationship of the A genome of polyploid wheat and T. urartu. The heteroduplex thermal stabilities indicated that T. searsii was most closely related to the B genome of T. turgidum (AB) and that the genome of T. urartu and the A genome have a great deal of base-sequence homology. Thus, it appears that T. searsii is the B-genome donor to polyploid wheat or a major chromosome donor if the B genome is polyphyletic in origin.

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