长雄野生稻及其后代抑草效果与化感潜力和农艺性状的关系

明确化感潜力和农艺性状对长雄野生稻(Oryza longistaminata)及其后代抑草效果的影响及相互关系,对发掘与利用野生种质资源的化感基因培育水稻化感新品种具有重要意义。本研究以化感抗稗草长雄野生稻、亚洲栽培稻‘RD23’及其杂交F1代(RD23×O.longistaminata)和F2代单株分离群体为材料,采用室内生物测定和温室盆栽试验相结合方法,研究化感潜力和农艺性状对长雄野生稻及其后代抑制稗草的影响,并探讨三者的相互关系。结果表明,室内生物测定为强化感潜力的水稻材料在盆栽条件下对稗草的密度防效、生物量防效和株高抑制作用并非总强于弱化感和无化感作用的水稻材料,但在根际距离0~3 cm时,强化感潜力水稻材料对伴生稗草的抑制效应显著强于弱化感潜力和无化感作用的水稻材料。不论供试材料化感潜力强弱,当根际距离大于3 cm时,株型高大、分蘖强的供试水稻材料在盆栽条件下对稗草的密度防效、生物量防效和株高抑制作用均显著强于株型矮小、分蘖少的材料。供试水稻材料在不同苗龄对稗草的抑制作用也存在显著差异,苗龄60 d的供试材料在根际距离0~3 cm范围内对伴生稗草的密度防效均小于苗龄30 d的对应处理组,但对伴生稗草的生物量防效和株高抑制作用则大于苗龄30 d对应处理组;之后随着距离的增加,除根际距离在3~6 cm的密度防效外,其他均无显著差异。在根际距离0~3 cm时,供试材料的化感综合效应指数(SE)与对伴生稗草的密度防效、生物量防效和株高抑制作用显著相关,但随根际距离的增加相关性逐渐减小;株高和分蘖数与稗草的密度防效不相关,与生物量防效和株高抑制作用存在一定的相关性。研究结果显示,长雄野生稻及其后代田间抑草效果与化感潜力、苗龄、株高和分蘖数等因素相关,在根际距离0~3 cm时,化感作用在苗龄30 d的强化感潜力水稻材料的抑草效应中起主要作用。

Relationships among weed suppression effect, allelopathy and agronomic characteristics of Oryza longistaminata and related descendants

Rice allelopathy has been a new environmentally-safe way in paddy weed management that has met the needs of sustainable agriculture. This study explored the linkages among field weed suppression effects, allelopathy and agronomic characteristics of Oryza longistaminata and its related descendants. It critically exploited and utilized the important aspect of allelopathic genes of wild resources of rice germplasm. In the paper, wild rice (O. longistaminata) with allelopathic potential and 'RD23' (O. sativa cultivar) without allelopathic potential and their F1 (RD23 × O. longistaminata) and F2 descendants were used in indoor assay and pot cultivation experiment in greenhouse to determine the effect of allelopathy and agronomic characters on weed suppression effects to barnyard grass. The results showed that weed suppression effects of strong allelopathic potential rice were significantly higher than those of rice with weak allelopathic and non-allelopathic potential at a rhizosphere distance of 0?3 cm under pot culture conditions. However, strong allelopathic potential rice not always had higher weed inhibition effects with increasing rhizosphere distance. When rhizosphere distance was greater than 3 cm, rice with strong tillering ability, fast growth and long upright stems had stronger weed inhibition effects under pot culture conditions irrespective of the allelopathic potential of the tested rice materials. Density control effect of rice seedlings aged 60 days was lower than those aged 30 days at rhizosphere distance of 0?3 cm. However, biomass control effect and plant height inhibition rate were greater for seedlings aged 60 days. With increase of rhizosphere distance, not significant difference was noted between seedling with two ages, except density control effect at rhizoshpere distance of 3?6 cm. Correlation analysis of allelopathy synthesis effects with density control effect, biomass control effect and plant height inhibition rate depicted weakening correlation with increasing rhizosphere distance of the tested rice materials, but with significant correlation at 0?3 cm rhizosphere distance. Although no correlation was noted between plant height, tiller number and density control effect, but biomass control effect and plant height inhibition rate was positively correlated with plant height and tiller number of the tested rice materials. The study suggested that field weed suppression effect of O. longistaminata and its F1 (RD23 × O. longistaminata) and F2 accessions depended on allelopathy, seedling age, plant height, tiller number and other factors of the rice field. Allelopathy was an important factor at 0-3 cm rhizosphere distance and 30 days of rice seeding age.