Genetic analysis of F2, F3, and backcross populations supported the hypothesis that erucic acid content in seed oil of plants of Brassica napus L. is governed by two genes displaying no dominance and acting in an additive manner. Environment appeared to influence erucic acid content, especially in genotypes capable of producing a large amount of this acid. Methods for the breeding of plants of Brassica campestris L. with zero erucic acid are outlined and it is suggested that similar methods could be used to breed for or against other fatty acids.

Reciprocal crosses were made between plants of Brassica napus with seed oil containing 40 and 0 per cent erucic acid. Gas liquid chromatographic analysis snowed an erucic acid content of 22 to 24 per cent in the crossed seeds. These results indicate that dominant gene action is absent and that fatty acid composition of the oil is controlled by the developing embryo. Thus the seed on an F1 plant constitutes an F2 population.Methods were developed to determine the fatty acid composition of oil from single seeds and from one cotyledon of an embryo. The analysis of a single cotyledon allows the genotype to be determined one generation earlier than if bulk samples are used, and the remainder of the seed may be grown into a normal plant. It is suggested that this half-seed technique may be used to determine the inheritance of other fatty acids in Brassica, and may also be applied to breeding other oil crops where the embryo, rather than the maternal sporophyte, controls the synthesis of fatty acids.

Salinity-calcium interactions, which have been shown to be important in plants grown in dryland saline soils of the Canadian prairies, were studied in two species differing in salt tolerance. In solution culture, wheat showed a greater reduction in growth and a higher incidence of foliar Ca deficiency symptoms than barley when grown under M g S O 4 or Na2SO 4 plus M g S O 4 salt stress. Amendment of the saline solution with Ca to increase the Ca/(Na + Mg) ratio ameliorated the effects of salt, but more so in wheat than in barley. At least part of the difference in salt tolerance between the two species must therefore relate to species differences in the interaction of salinity and Ca nutrition. The greater response of wheat to Ca was not due to a lower Ca status in leaf tissue; on the contrary, although Ca amendments improved tissue Ca/(Na + Mg) ratios in both species, salinized wheat had equivalent or higher Ca content, and higher Ca/(Na + Mg) ratios than did barley. The higher Ca requirement of wheat is apparently specific to a saline situation; at low salinity, wheat growth was not reduced as extensively as that of barley as Ca/(Na + Mg) ratio was decreased. High night-time humidity dramatically improved wheat growth under saline conditions, but increasing the Ca concentration of the saline solution had no effect on growth in the high humidity treatment. Membrane leakage from leaf tissue of wheat grown under saline conditions was increased compared to tissue from non-saline plants. Plants grown in Ca-amended saline solutions showed no increase in membrane leakage. These results confirm the importance of Ca interaction with salinity stress, and indicate differences in species response.

No abstract

Foxtail barley (Hordeum jubatum L.), a wild species that can inhabit highly saline environments, may have more potent salt‐tolerance genes than commercial barley (H. vulgare L.). The objective of this study was to compare the growth and ion relations of the commercial cultivar Harrington with foxtail barley under saline conditions, to determine whether a differential response to salinity stress exists between these species. Seedling performance was evaluated as a function of increasing concentrations of Na2SO4, MgSO4, and CaCl2 (within the electrolyte conductivity range of 0.26 to 1.38 S m−1) and the Ca mole fraction (Camf) of salt treatments in solution culture experiments. The Camf of the salt treatments, defined as the molar ratio of Ca/(Ca + Na + Mg), was maintained at 0.02 or 0.09. Salt treatments at a Camfr of 0.02 significantly reduced leaf area, shoot growth, root growth, and the root‐to‐shoot ratio (R/S) of Harrington seedlings relative to foxtail barley. Growth of Harrington seedlings improved substantially when the Camf was increased from 0.02 to 0.09. The two genotypes differed significantly in root weight and R/S under saline conditions; these differences were independent of the Camf. Evaluation of root and shoot tissue ion contents revealed that H. jubatum seedlings accumulated less Na from the medium than Harrington and preferentially compartmentalized Na in root rather than shoot tissue. The wild species maintained higher levels of Ca, had more favorable K/Na ratios, and maintained higher R/S levels of SO4 than Harrington. Differences between H. jubatum and Harrington in root and shoot ion accumulation suggest that membrane permeability and selectivity properties are controlled by both genotype and Ca supply.

Frequently repeated control plots and the moving mean of adjacent plots were compared as methods of controlling error in single‐row plots of barley, Hordeum sativum Jess. (H. vulgare L.) Adjustment by either technique was more effective for grain protein content than for grain yield. Covariance adjustment using either moving mean or control plots prevented overadjustment in several instances and was always more effective than percentage adjustment in reducing experimental error. Repeated control plots and moving means gave similar control of experimental error, but control plots had less practical application than moving means. A partially balanced lattice design accomplished superior control to both methods using percentage adjustment and similar control using covariance adjustment. In cases where the number of entries was too large to accommodate an incomplete block design, covariance adjustment using the moving mean would be advantageous.

No abstract

Cell suspension cultures of Triticum monococcum, Triticiam aestivum, Glycine max, Melilotus alba, and Haplopappus gracilis, were examined to determine whether chromosomal changes had occurred during culture. All cultures except H. gracilis showed change in chromosome number and the two species of Triticum showed abnormal karyotypes.