The production of α‐amylase by the endosperm of barley varieties, both commercial and non‐commercial, in normal germination and after incubation with gibberellic acid, has been measured. The level of activities produced differed considerably between varieties. All varieties tested produced considerably more enzyme when supplied with a source of exogenous gibberellic acid than under normal germination. In general the differences between varieties were less in the de‐embryonated treatment.

SUMMARYThis paper reports the heterotic pod production of three different crosses between a Nigerian local selection (N38) and three Trinidad Introductions (CF47, CF56 and CF207). The hybrids consistently outyielded the inbreds throughout the first 19 years of pod production. N38 × CF56 hybrid produced the highest number of pods per tree, closely followed by N38 × CF47 hybrid; while N38 × CF47 hybrid showed the best heterotic response. Pod production figures of (CD207)2 and (CD302)2, both double inbreds of N38, support the hypothesis that N38 is a Trinitario × local selection hybrid which segregate for pod production.

The amount of activity, the thermal stability and the calcium retaining ability of a-amylases produced by different barley varieties and their reciprocal hybrids have been investigated. a-Amylase was produced by seeds germinated normally and by de-embryonated seeds incubated with gibberellic acid. The activity of the enzyme has been compared between lines on various bases and the validity of these comparisons is discussed. The inactivation constants of the partly purified enzymes dialysed against EDTA in the presence of trypsin have been calculated and compared. Similarly the rate of thermal inactivation of the enzymes has been investigated. In general, little evidence was found to suggest that heterosis existed in terms of any of the characteristics studied.