No abstract

Twelve varieties each of barley and wheat and 10 of soybeans were grown in 2 years at two locations to assess genetic and environmental variation in accumulation of 12 mineral elements. Seedling leaves and seed of barley and wheat and seed of soybeans were assayed. Varietal differences in accumulation of P, K, Mg, Na, Ca, Mn, B, and Sr were significant in most plant materials studied. In contrast, differences in accumulation due to years and locations generally were small and non‐significant.A few of the genotype ✕ environment interactions were statistically significant but the majority of them were nonsignificant, and all the interaction components were smaller than the experimental error. Also, estimates of genetic variane were larger generally than interaction components. The consistency in performance of genotypes across years and locations indicates that a single environment may suffice when screening genotypes for differences in mineral accumulation.Genetic correlations involving accumulation of a particular element in seed and seedling leaves were positive and near 0.4 to 0.5. Ca and Sr accumulation were highly correlated in all plant materials. In soybean seed, P, Ca, Sr, Mg, and Mn accumulations were highly and positively correlated.

Callus from 17 of 23 single crosses and 10 of 17 inbreds of Zea nmys L. was isolated from mature embryos grown on Linsmaier and Skoog RM medium with 15 mg 2,4-dichlorphenoxyacetlc acid (2,4-D) per liter. This callus growth was greatest from the first node of the seedling shoot; occasionally callus growth was observed from the radicle and coleoptile regions. All callus was easily transferred and maintained on media with 2 mg 2,4-D/liter.Genetic variability for callus growth was observed among both single crosses and inbreds. Callus was initiated from 70% of 23 single crosses tested and from only 40% of the 17 inbreds tested. The most rapidly growing cultures were isolated from OhSIA X Os420 which had a 20-to 25-fold fresh-weight increase during a 30-day incubation at 30 C.Cultures maintained on 2,4-D did not require cytokiuins for growth, nor was 2,4-D effectively replaced by idoleacetic acid or ,~-napthaleneacetic acid. Several complex media additives were studied and only 800 mg yeast extract/liter and 200 mg casamino acids/liter individually stimulated significant increases in fresh weight over unsupplemented media. The callus from OhS1A X Os420 has been maintained for 20 months with transfer to fresh media every 30 days (representing 19 subcultures).

No abstract

Five adapted varieties of spring oats, Avena sativa L., were used in a study of intergenotypic competition. All pairwise combinations of the five varieties were grown at two locations at four levels of competition in hills and three levels in rows. Some varieties were enhanced and other varieties suppressed in yield as a result of competition in both hill and row plots at both locations. The maximum effect measured was with the variety ‘Rodney’ which yielded 62% more when surrounded by hills of ‘Goodfield’ than when surrounded by itself. Varieties that were strong competitors yielded more, relative to weak competitors, when grown in single hill plots than in rows or hills bordered by the test genotype (testor). Yield of testors was negatively correlated with differences between testor and competitor height and maturity. However, mature height and date of heading were not significantly influenced by competition. The effects of competition were more pronounced for yield per se than for any of the yield components. Panicle number and number of seeds per panicle were affected more than seed weight.