The direct use of mutation is a valuable approach to generate variability in crops. The electron beam, one of the ionizing radiations, has been applied to evaluate its effect on seed germination and early seedling growth of creeping bentgrass (Agrostis palustris Huds., cv Penn-A1). The mature dry seeds were irradiated with various electron beam energies (0.3, 1.0, 1.3, and 2 MeV) and current levels (0.03 and 0.06 mA). Although large variability was existed within each dose, distinct difference of germiability and seedling vigor were not found at 0.3 MeV / 0.03 mA and 0.3 MeV / 0.06 mA beam condition. However, 1.0 MeV / 0.06 mA application most effectively inhibited and retarded seed germination and most severely restricted cotyledon and root growth in early seedling growth. The direct use of electron beam would be a valuable supplementary approach to generate mutants suitable for breeding purposes.

This work aims to propose synchronic head-initial solutions for the two major puzzles of Old English pre-modal constructions, that is, the coexistence of lexical and modal interpretation and complicated ordering patterns. Concerning the dual nature of pre-modal verbs, it is argued that lexical- and modal-type pre-modal verbs have different thematic structures. A lexical-type pre-modal verb constitutes a two-place predicate and selects an external argument controlling the empty pronominal subject of an infinitival clausal complement. A modal-type pre-modal verb, on the other hand, lacks its own external argument and allows the subject of an infinitival clausal complement to undergo movement into a specifier of a higher T. Diverse ordering patterns of pre-modal verb complexes result from leftward operations. An infinitival main verb moves onto a complex of a finite pre-modal verb and a light verb v, as long as the operation is required for a verbal affixation. The complement of an infinitival main verb undergoes raising implemented by the EPP features of a light verb v. The head-initial analysis also provides an appropriate explanation for Old English causative and perception verbs with an infinitival complement.