小麦种子黑胚病发病规律研究

链格孢Alternaria alternata(Fr.)Kiessler是小麦种子黑胚病的主要致病菌。1987～1988年在鲁麦8号小麦抽穗、开花及籽粒发育各阶段自穗部进行分离,结果表明:小麦籽粒乳熟后期(花后20天)病菌开始侵染胚部,引起黑胚,随着籽粒成熟黑胚率相应增加。在此期间遇雨或田间相对湿度高(90%以上),易结露,则黑胚病加重。室温26～27℃下接种,病害潜育期为3～4天。大气中的链格孢菌是小麦种子黑胚病的侵染源。小花上残留的花药是病菌进入花内的途径之一。小麦黑胚病普遍发生,不同品种(品系)有差异。高肥水地种子黑胚率高于旱地,雨后收获的种子黑胚病亦较雨前收获的重。黑胚粒的粒重大于非黑胚粒。

STUDIES ON THE REGULARITY OF THE DEVELOPMENT OF BLACK POINT ON WHEATSEED

The black point of wheat seed was induced mainly by Alternaria alternata(Fr.) Kiessler. The resuhs of isolation at heading, anthesis and kernel development stages in 1987 and 1988 showed that Alternaria alternata (Fr.) Kiessler infected the embryo to cause black point during late filling period (20 days after anthesis). and black point rate increased with kernel ripening. The black point was obviously serious as relative humidity of atmosphere in the fields increased (above 90%) or it was raining during those periods. The incubative stage was 3-4 days when the heads were inoculated at room temperature 26-27C. The infeeting sourse of black point of wheat seed was Alternaria alternata (Fr.) Kiessler in atmosphere. One of the approaches through which the fungus infected the floret was the remaining anthers. Black point of wheat existed widely, but different varieties (strains) varied in its incidence. Black point rate of seed grown in high N-water conditions was higher than that of seed grown in dryland. Black point of seed harvested after raining was more serious than that of seed harvested before raining. The hundred (or thousand) seed weight with black point was obviously higher than that of the normal seeds of the same variety.