杂交粳稻13.5t hm~(-2)超高产群体动态特征及形成机制的探讨

选用杂交粳稻甬优8号,以国家粮食丰产工程兴化、姜堰实施基地1.0hm2连片与6.67hm2连片超高产攻关方为依托,研究了13.5thm-2超高产群体特征,并探讨了群体形成机制。结果表明,较之12.0thm-2左右群体,13.5thm-2群体的穗型大,群体颖花量多(60000×104hm-2以上),有效穗数、结实率和千粒重与之相当;群体茎蘖于生育前期稳步增长,至有效分蘖临界叶龄期达适宜穗数,高峰苗出现在拔节期,数量少,为预期穗数的1.3倍左右,此后群体平缓下降,至抽穗期达适宜穗数,成穗率高(75%);群体叶面积指数前期增长相对较缓慢,最大值出现在孕穗期,为8.5左右,此后下降缓慢,成熟期仍保持在4.0以上;群体光合势生育前期较小,中、后期较大,总光合势为675×104m2dhm-2以上,抽穗至成熟期的光合势占总光合势的45.0%以上;群体拔节前干物质积累速度相对较缓、积累量略低,拔节后积累速度较快,至抽穗期群体生物量为13.5thm-2以上,抽穗后积累量亦高,一般为9.75thm-2以上,总干物重高达23.25thm-2以上。13.5thm-2超高产群体形成机制为,依靠精苗,发大蘖,及时够苗,提高够苗期群体质量(有效分蘖临界叶龄期),为中期高质量群体结构的培育奠定生物学基础;依靠合理的群体动态及其规模,培育适宜数量的壮秆大穗,于抽穗期形成具有强抗倒力和巨量安全库容的高光效群体;依靠平稳消退的光合系统,提高抽穗后群体光合物质生产力,增大群体库容的总充实量,并维持较大的茎鞘强度,增强群体的安全抗倒力。

Population Characteristics and Formation Mechanism for Super-High-Yielding Hybrid Japonica Rice(13.5tha-1)

Population characteristics of super-high-yielding hybrid japonica rice (13.5 t ha^-1) were studied and its formation mechanism was explored using Yongyou 8 as material in Xinghua and Jiangyan. Results showed that population of 13.5 t ha^-1 had more spikelets per panicle and total spikelets than population of 12.0 t ha^-1. There was no significant difference in panicles, filled-grain percentage and 1000-grain weight between populations of 13.5 t ha^-1 and 12.0 t ha^-1. Population of 13.5 t ha^-1 exhibited fewer tillers at the early growth stage and achieved excepted number of stems and tillers at critical leaf-age for productive tillers, whose max number of stems and tillers was at jointing stage and was about 1.3 times of excepted number. Then, the number of population stems and tillers began to decrease stably, which achieved expected number again. At last, ratio of productive tillers to total tillers of 13.5 t ha^-1 population was more than 75%, which was higher than that of population of 12.0 t ha^-1.The leaf area index of 13.5 t ha^-1 population was lower than that of 12.0 t ha^-1 population at the early growth stage, and the max leaf area index was about 8.5 at booting, which decreased stably and was above 4.0 at maturity. The photosynthetic potential of population with 13.5 t ha^-1 was small at early stage and larger at middle and late stages, as compared with population with 12.0 t ha^-1. The total photosynthetic potential was above 6.75×10⁶ m² d ha^-1, of which most than 45.0% was from heading to maturity. The dry matter accumulation was smaller compared with population with 12.0 t ha^-1 before jointing, and the weight of it was above 60 kg ha^-1 at heading, which was significantly higher than that of population with 12.0 t ha^-1. The total weight of dry matter was above 23.25 t ha^-1, of which above 9.75 t ha^-1 was accumulated from heading to maturity. Formation mechanism of super-high yielding population (13.5 t ha^-1) was that: population quality was enhanced at critical leaf-age for productive tillers through cultivating strong seedlings, germinating low positiontillers and achieved expected number of stems and tillers in time, which formed the biological foundation for high quality population at middle stage; in order to form high photosynthetic efficiency of population structure with strong lodging-resistance and large population spikeletes at heading, suitable number of strong stems and large panicles was cultivated through establishing suitable dynamic and size of population; in order to enlarge sink-filling and keep strength of stems and sheaths, dry matter accumulation was enriched after heading through photosynthetic system smooth and steady fade away.