An extension of the code is planned to cover, in the first instance, maize and sorghum, and, subsequently, forage grasses and dicotyledonous crops, and a full version, with illustrations, will he published elsewhere. It is very much hoped that the final version will not differ significantly from that published here, but any suggestion for minor amendments or for changes in phraseology would he welcomed.

When seedling roots of wheat (Triticum aestivum L. em Thell.) are treated with solutions containing A13+ and then stained in an aqueous solution of hematoxylin, they develop a pattern of staining that correlates remarkably well with their A1 tolerance level as estimated by root elongation methods and field trials. A rapid and simple method for evaluating A1 tolerance hi wheat varieties with hemotoxylin is presented. The method is based on a visual estimation of the stainability of the root tips of young seedlings and is calibrated with wheat varieties of known A1 tolerance. Since seedlings tested by this method are still viable and can be transplanted for growing to maturity, the method can also be adapted for screening segregating populations.

An efficient doubled‐haploid production technology that induces homozygosity can greatly reduce the time and cost of cultivar development. Low efficiency of doubled‐haploid production previously has limited exploitation of this method for crop improvement. This study aimed to develop a more efficient and effective isolated microspore culture system for generating doubled‐haploid wheat (Triticum aestivum L.) plants. We report here the development and testing of a new chemical formulation for its efficiency to induce microspore embryogenesis, and the development of a system for double haploid production, in which the induction of embryogenesis in microspores was followed by isolating embryogenic microspores, and culturing them under optimized growth conditions to produce high embryoid yields. Up to 50% of the total treated microspores in the whole spike were converted from their preprogrammed gametophytic to a sporophytic pathway by a chemical inducer formulation consisting of 0.1 g L−1 of 2‐hydroxynicotinic acid, 10−6 mol L−1 2,4‐dichlorophenoxyacetic acid, and 10−6 mol L−1 6‐benzylaminopurine. The isolated embryogenic microspores were cocultivated with live wheat ovaries in a liquid NPB 99 media with an osmolality of about 300 mOsmol kg−1 H2O, resulting in the regeneration of 50 to 5500 green plants per single spike of eight wheat genotypes. The high efficiency and simplicity make the system practical for biological research and for accelerating cultivar development in wheat breeding programs.

Yield losses occur in cereals as a result of lodging. Ethephon [(2‐chloroethyl)phosphonic acid] has been reported to reduce lodging; however, studies of its effect on grain yield have produced conflicting results. In this study. selected cultivars of semidwarf wheat (Triticum aestivum L.), normal height barley (Hordeum vulgare L.) and triticale (Triticale hexaploid L.) were treated with ethephon to determine (1) if this growth regulator had an effect on yield other than via a reduction in lodging and (2) the optimum growth stage and rate (kg/ha) of application. Foliar‐applications to field grown plants (the soil was a fine‐silty, mixed, mesic Cumulic Haplaxeroll) were made at two plant growth stages, late boot and early heading. Ethephon was applied at 0, 0.28, and 0.55 kg&ha in 1976 and at 0, 0.28, 0.55, and 0.85 kg/ha in 1977. Main plots were fertilized with 45 or 90 kg N/ha in 1976 and 90 or 180 kg N/ha in 1977. Ethephon applications at the late boot stage reduced the elongation of plants more effectively than applications at early heading. Ethephon treatments reduced elongation of tall cereal species, i.e., barley and triticale were significantly shorter following treatment of 0.28 kg/ha in 1977. Ethephon treatments increased harvestable yields when they reduced lodging. For instance, untreated ‘Unitan’ barley lodged heavily, but ethephon treatment of 0.55 kg/ha reduced lodging which resulted in increased harvestable yields. Ethephon treatment of 0.84 kg/ha significantly inhibited stem elongation in semidwarf wheats, but semidwarf wheats did not lodge and treatment did not increase yields. The results of this study indicate that further field testing should be conducted in regard to ethephon's potential to benefit yields of tall, ‘weak‐stemmed’ cereals such as barley, since no benefit was derived from ethephon treatment to semidwarf wheats.