Analyzes of Echinochloa plant differentiation into lowland and upland weeds, and of their physiological and biochemical adaptation modes.

为明确棘豆属低地杂草和旱地杂草对各自生境的生理生化适应性，以及了解六倍体低地杂草和旱地杂草的起源品种--十字草(E.crus-Galli var.crus-Galli)的形态和生理分化，进行了试验和田间调查。在4ﾟC条件下，将沉睡的低地杂草(E.crus-Galli var.formosensis)和旱地杂草(E.c.var.praticola)的种子埋入土壤中，前者种子很容易在淹水条件下解除休眠，而后者种子在不同的萌发温度下都能很好地萌发，无论埋藏土壤的土壤湿度如何。未休眠的低地杂草种子萌发不需要氧气，ADH和细胞氧化酶的Km值分别低于需要氧气萌发的旱地杂草种子和高于旱地杂草的Km值。因此，它们在种子休眠和萌发过程中适应不同生境的生理生化模式不同。水稻群体的祖先品种E.C.var.crus-Galli在形态上倾向于与水稻相似，在开阔地、堤岸和路边对土壤干旱的耐受性低于其他群体。水稻群体中的许多个体也具有厌氧种子发芽力和较低的休眠程度。种子ADH酶谱对种子厌氧发芽力的影响不明显。

Experiments and field survey were conducted with objectives to clarify physiological and biochemical adaptations of lowland and upland weeds of the genus Echinochloa to their respective habitats, and to know morphological and physiological differentiation within a variety, E.crus-galli var.crus-galli from which the hexaploid lowland and upland weeds originate.When dormant seeds of the lowland (E.crus-galli var.formosensis) and upland (E.c.var.praticola) weeds were buried into soil at 4ﾟC,the former seeds were readily released from dormancy in the soil with flooded conditions while the latter seeds germinated well under alternative germination temperatures regardless the soil moistures of the soil where they had been buried. Non-dormant seeds of the lowland weed did not required oxygen for germination and had lower and higher Km values of ADH and cyt.oxidase, respectively, than the upland weed which required oxygen for germination. Physiological and biochemical modes for adaptation to their respective habitats are thus different between them in seed dormancy and germination.Plants of the ancestry variety, E..c.var.crus-galli from rice paddy populations tended to have morphological mimicry to rice, and they showed lower tolerance to soil drought conditions than those from other populations at openland, levee and roadside. Many individuals of the paddy populations also had anaerobic seed germinability and lower degree of the dormancy. It was not evident that ADH zymogram of a seed affected to anaerobic germinability of the seed.