Hayashi et al. (1980) investigated morphological and physiological features of more than 200 strains which were collected by Dr. J. R. Witcombe in 1974 and 1976 from four districts (named A, B, C and D in this paper) of northern Pakistan and India (Figure 1). According to them, 90-100% of the strains in A and B districts and 20-50% of the strains in C and D districts were of spring growth habit (Table 1). A further study was made of the genotype constitutions for spring growth habit using these Witcombe's collections, together with Tibetan strains collected by Dr. H. Smith (1935).

F₂ hybrids from crosses between spring strains of the collections and some certain winter cultivars with known genotypes and their F₃ strains were grown under 24 hr illumination in a greenhouse, and investigated for segregation of spring and winter type plants. In these experiments, two kinds from A and B districts were mainly of Sh₂Sh₃ genotype, while those from C and D districts were mostly Sh₂ genotype. On the other hand, Tibetan spring barleys consisted of Sh₂Sh₃ and Sh₂ genotype strains in almost the same frequency, with one exception of one recessive and one dominant genotype strain, ShSh₂

According to our study hitherto made of spring varieties collected from various regions of the world, the Sh₂Sh₃ genotype occurs most frequently in North Pakistan, North India, Tibet and Ethiopia. Furthermore, according to collectors' records, these genotype strains were collected in rather higher altitude than those of the Sh₂ genotype. This may suggest that the Sh₂Sh₃ genotype strains are more adaptive to higher altitude than the Sh₂ genotype ones.