Foliar sprays against potato common scab: compounds related to 3,5-dichlorophenoxyacetic acid

In glasshouse tests against the soil-borne disease potato common scab (Streptomyces scabies), foliar sprays (0 · 9 mm) of several compounds inhibited symptom development as effectively as 3,5-D (3,5-dichlorophenoxyacetic acid). These compounds were of two main types: (1) compounds very similar in structure to 3,5-D, viz. 3,5-disubstituted phenoxyacetic acids in which the substituents were dibromo-, di(trifluoromethyl)- or any combination of bromo-, chloro- and iodo- except diiodo-; (2) compounds which could be metabolized to 3,5-D within the plant, viz. 4-(3,5-dichlorophenoxy)butanoic acid, 3,5-dichlorophenoxy-acetamide, 3,5-dichlorophenoxy-N,N-diethylacetamide and 2-(3,5-dichlorophenoxy)ethylamine. No compound of either type was significantly more effective than 3,5-D, and those which were as effective shared its effects on tuber yield, number and shape. About 30 other compounds related to 3,5-D were less effective or ineffective.     

Detection of chromosomes carrying genes for seed dormancy of wheat using the backcross reciprocal monosomic method

Preharvest sprouting (PHS) in wheat represents a major constraint to the production of high‐quality grain. Genetic variation for tolerance to PHS is associated with seed dormancy. The present study was initiated to detect homologous chromosome variation associated with seed dormancy genes in a PHS tolerant cultivar ‘Zenkojikomugi’ (Zen) and ‘Chinese Spring’ (CS) using the backcross reciprocal monosomic method. The most striking effect on variation in seed dormancy was associated with chromosome 3A, and followed by group 4 chromosomes. These chromosomes of Zen increased dormancy compared with the respective CS homologues. Chromosomes 2D and 7D of Zen, and 6A of CS seemed to contribute smaller positive effects on dormancy. Chromosomes 2A of CS and Zen, as well as 3B, were equally effective in enhancing dormancy. The chromosome 3 A factors were independent of the grain‐colour gene R‐A1 because Zen was found to carry the white‐grained R‐A1a allele, which was identical to that of CS, and there was no difference in dormancy between the reciprocal F₁ seeds.     

Allelism of two genes for stem rust resistance in triticale

Summary Inheritance studies involving Coorong and Satu triticales showed that each possessed a single dominant gene for resistance. The genes were allelic or closely linked. The relative frequencies of Sr27 (Coorong gene) and Sr _Satuin a sequence of International Triticale Screening Nurseries were similar. However, a significant increase in the frequency of entries with Sr_Satu occurred in the 17 International Triticale Screening Nursery (ITSN).