Abstract:

The objective of this study is to explore the growth pattern and differences of stem and panicle of indica hybrid rice under various planting methods in panicle differentiation stage, and to investigate the effects of planting methods on grain formation. A split plot experiment was carried out in 2014 with two factors, including variety (Yixiangyou 2115 and F you 498) and planting method (mechanized direct-seeding, MD; mechanized transplanting, MT; hand transplanting, HT).The Growth pattern of stem and panicle, the formation characteristics of grain were researched, and the relationship between meteorological factors in panicle differentiation stage and the growth of stem and panicle were analyzed. The results were as follows: 1) Length of first to third elongated internodes from the base stablized 20 d, 16 d and 12 d before heading,respectively, indicating that reducing length and increasing roughness of basal first and second internodes should be done 16 d before heading. Dry panicle weight and ratio of panicle to stem increased rapidly 12 d before heading. 2) Dry weight ratio of panicle to stem was significantly positively correlated with rachis branches and spiketets from 16 d before heading to heading date. The ability that panicle competing assimilates with stem directly affected the formation of grain. 3) MT had higher dry weight ratio of panicle to stem in middle and late differentiation stage of panicle, MT also had higher dry matter accumulation of panicle than MD and HT in heading stage. So MT had an advantage in the number of grains. MT also had higher crop growth rate of population and higher dry matter accumulation per stem and population than MD and HT after jointing. MT also had higher leaf area index in heading, and its grain leaf ratio was higher than MD, so MT contributed to more grains and spikelets, longer panicle length. F you 498 with large panicle had higher dry matter weight of panicle in heading than Yixiangyou 2115 with middle panicle, and it had higher dry matter weight ratio of panicle to stem than Yixiangyou 2115, these were the important reason for that F you 498 had higher number of grains. Denser grain of F you 498 compared to Yixiangyou 2115 resulted from its larger leaf area index and grain to leaf ratio.4) MT had the longest growth duration,while MD had the shortest. MT had a longer panicle differentiation stage, higher accumulated temperature and illumination hours, providing a good temperature and light condition for the formation of grain in MT. Length and dry weight of stem and length of panicle were greatly influenced by meteorological factors. Suitable temperature and a certain amount of accumulated temperature before booting was conducive to the elongation of stem and panicle and filling of stem. Given the differences in growth under different planting methods and of varieties, we should take measures to regulate growth of stem and panicle and the distribution of assimilates in an appropriate time. In order to achieve the goal of increasing grain yield, the dry weight ratio of panicle to stem should be increased on the basis of cultivating strong stalk.

Key words: rice, panicle, stem, formation of grain, mechanized transplanting, mechanized direct-seeding, meteorological factors.

摘要：

为探明不同播栽方式下杂交籼稻幼穗分化期茎秆和幼穗生长的规律及差异以进一步明确不同播栽方式穗粒形成特点,于2014年采用两因素裂区试验设计,研究了机直播、机插和手插3种播栽方式下2个不同穗粒型杂交籼稻组合[宜香优2115(中穗型)和F优498(大穗型)]的穗分化期茎秆和幼穗生长规律和穗粒形成特点,并分析了幼穗分化期气象因素与幼穗和茎秆生长的关系。结果表明:1)基部向上第1至第3伸长节间长度分别在抽穗前20 d、16 d、12 d后趋于稳定,故基部第1、2节间的降长增粗应在抽穗前16 d之前;穗干质量和穗茎比在抽穗前12 d后迅速增加。2)从抽穗前16 d开始至抽穗期,穗茎干重比与多数枝梗和颖花性状呈显著或极显著正相关,穗与茎秆竞争同化物的能力直接影响到穗粒形成。3)机插穗分化中后期穗茎干质量比较高,且抽穗期穗干质量显著高于手插和机直播,有利于提高其每穗粒数,且机插拔节后群体生长率及单茎和群体干物质积累量较高,抽穗期叶面积指数较高,粒叶比高于机直播,较机直播更利于粒重的提高和穗长及着粒数的增加;大穗型品种F优498抽穗期穗干质量显著高于中穗型品种宜香优2115,且穗分化后期穗茎干质量比高于宜香优2115,是其每穗粒数高的重要原因;F优498穗部着粒较密,较大的叶面积指数及粒叶比利于大穗的形成。4)机插全生育期最长,机直播最短,且机插穗分化期历时较长,穗分化期积温和日照时数较高,为穗粒形成提供了较好的温光条件;茎秆长度和干质量及穗长受气象因子影响较大,孕穗前适宜的温度和一定的积温有利于茎秆和幼穗伸长及茎秆的物质充实。生产上应针对不同播栽方式及品种的生育进程差异,适时采取措施调节茎秆和幼穗生长及物质分配,在培育壮秆的基础上提高穗分化期穗茎比以达到增粒增产的目的。

关键词: 水稻, 穗, 茎秆, 穗粒形成, 机插, 机直播, 气象因子