Differentiation Research Of Shoot Apical Meristem Of Puccinellia Chinampoensis On Songnen Plain

Puccinellia chinampoensis,also known as Yang Hudunzi or Lu Getou in china,is a perennial grass of Gramineae in alkaligrass family.It is a vanguard plant that will improve the saline and alkaline land and fine turf grass for developing the agriculture and animal husbandry in Three North regions of China. In the natural state, the absolute advantage asexual reproduction of Puccinellia chinampoensis limited its application by people. This paper researched on Puccinellia chinampoensis in Songnen Grassland through the method of paraffin sections.By dynamic anatomical study on shoot apical meristem (growth cone) we expected to reveal the differentiation regulation of shoot apical meristem(Vegetative tiller) of Korean alkaligrass, to explain its sexual reproduction process and to provide a theoretical basis on improving the seed production.The differentiation of young spikelet of Puccinellia chinampoensis could be divided into six stages:Ⅰp rimary stage(the period of the leaf primordia differentiation),Ⅱelongation stage( differentiation of rachis primordia),Ⅲsingle ridge stage( bract differentiation phase),Ⅳs pikelet differentiation stage,Ⅴpanicle initiation stage,Ⅵheading stage.1,Dynamic anatomise study on Puccinellia chinampoensis found that a certain number of vegetative tillers appeared in elongation stage and single ridge stage before and after the heading stage,and there were the most vegetative tillers in the period of the elongation stage especially in June and in August.2,In spring, the apical cones enter spikelet differentiation stage. The apical cones enter the panicle initiation stage from the end of May or the early of June. The apical cones do not enter panicle initiation stage in the end of June. These results means the tiller whose apical cones enter spikelet differentiation stage can tassel.3,After heading stage, about 99.5% of the monopodium vegetative tiller enter into differentiation stage, 9% to the elongation stage ,90.5% to the single ridge stage, the differentiation of monopodium vegetative tiller ended in the single ridge stage.The reason needed further studying. The apical cone diameter of primary is 92.1±0um the minimum is92.1um and the maximum is 92.1um; the height is 81±0um, the minimum is 81um and the maximum is 81um. The apical cone diameter of elongation stage is 101.59±23.35um, the minimum is 64.9um and mdaximum is 156.8um; the apical cone height is 134.45±32.69um, the minimum is 91um and maximum is 201.2um. The apical cone diameter of single ridge stage is 123.7±32.49um, the minimum is 7.7um and maximum is 71um; the apical cone height is 201.94±64.61um, the minimum is 10.9um and maximum is 255.2um. These results showed the most of apical cones have changed from vegetative growth to reproductive growth, that is to say, 99.5% of the monopodium was under Floral Bud Differentiation.4,In spring , The height of the Puccinellia chinampoensis increased gradually before heading stage,and growed at the fastest speed in the panicle initiation stage and heading stage in the height, with a maximum of about 50cm.After the heading stage,the plants heights underwent two downward stages:one phase was the period that new seedings began to sprout after heading,the other phase was when winter grass began to unearth at the end of the growing season.The height of the plants declined in the two periods because the unearthed heights of the seedings had not yet reached the maximum height.Throughout the growing season, the height and diameter of vegetative tiller of Puccinellia chinampoensis presented of a significant positive correlation.In April 20th, the height of vegetative tiller of Puccinellia chinampoensis showed significantly positive correlations with these three following quantitative characters,the plant height, leaf age and dry weigh. In October 5th the height of vegetative tiller of Puccinellia chinampoensis had significantly positive correlations with leaf age and dry weigh ,but not with plant height, There were no pertinence among the height of vegetative tiller of Puccinellia chinampoensis, plant height leaf age and dry weigh except the two samples above.This paper first reported the differentiation behavior of monopodium vegetative tiller of Puccinellia chinampoensis, showed the differentiation regulation of its young spike and provide a theoretical basis on improving the seed production.