| Conducted an experiment at Chengjiachuan Village (30°52’N,103°56’E), Sandaoyan, Pixian, Chengdu in 2014, taking Indica Hybrid Rice variety Yixiangyou 2115 and Fyou 498 as materials, with artificial transplanting (AT) as the control to study the effects of direct seeding (DS) and mechanized transplanting (MT) on root trait of indica hybrid rice, and a split plot field experiment was conducted, planting method was the main area factor, varity was deputy area factor. The main results were as follows:(1) The author combines the design of undisturbed soil column method to process a set of rice root sampling device (patent numberZL20142010 7619.8), taking the whole excavation by 18cm bore cylinder subjected to root. Can also use the cylinder bit combined with different diameters to achieve different diameter stratified sampling, and can be performed in a longitudinal segmentation after taking out according to testrequirements, the whole device has the advantages of operation simply, can obtain the rice root system completely,it was a new attempt to solve the rice root sampling difficult.(2) Planting method has a significant effect on yield, yield was the verall MT> AT> DS, compared with AT, the average yield of MT increased by 6.67%,the average yield of DS decreased 4.98%. DS was significantly higher than MT and AT in panicle number; DS was significantly lower than MT and AT in grain number per spike, Fyou 498 significantly greater thanYixiangyou 2115 between varieties; 1000-grain weight had significant difference only in varieties.variety has the greatest effect on yield and it’s constitute, planting method has effect on spike number and grain number per spike mainly, interaction between varieties and planting method only had significant effect on the panicle number,DS has fewer spikelets per panicle, yield is low, MT has many and big spikes.(3) Root growth have significant differences in planting method before transplant, DS>AT>MT in total root length, diameter of root, root volume, root tips, and the difference was significant, the root-shoot ratio of DS was significantly higher than MT and DS, there was no significant difference between MT and AT. During Green period, MT and AT is given priority to with the growth of root, and root-shoot ratio increased, at the same time, the shoot of DS growth faster than root, root-shoot ratio decreased, the root morphological indexes was DS>AT>MT after green up. During green up period, the growth of root system included increasing the vertical extension, horizontal diameter and new root growth.(4) The root system of DS growth rapidly in the early, and growth a lot of thin roots after jointing stage, root tips number was significantly more than MT andAT in heading stage, diameter of root was significantly lower than MT and AT, the root-shoot ratio was large; the root ofMT growth amount is small in the early, root growth rapidly after the jointing stage, has the advantage of backwardness, single stem and total root length, root volume, root dry weight was maximum in the heading stage; the root of AT was little and coarse, root-shoot ratio was small.Mechanized planting is conducive to the growth of rice root system, both DS and MT are have certain advantages in the root growth than AT.(5) Compared with the AT, DS and MT has a shallow root distribution, DS, MT and AT root dry weight accounted for 76.9%,76.5%and 76.5% respectively to total root dry weight in 0-10cm soil layer, ratio of dry root weight in 10-20cmand>20cm soil layer DS and MT were lower than AT; in the horizontal direction, ratio of dry root weight to total root dry weight DS is higher 3.5% and 3.3% respectively than MT and AT in 0-12cm diameter range of under the shoot, it means the root of MT and AT is more concentrated under the shoot.(6) The root activity before transplanting was DS>MT> AT, the difference of each planting method was significantly; After MT and AT transplanted to the field,the root activity were increased by 108.9% and 308%, The root activity of DS that without a transplant in this period increased only 45.7%. Indica hybrid rice root activity showed a tendency to increase in the early, fertilizer and water environment change in the process of transplanting has a tremendous impact on the activity of roots. Root activity had no significant difference between each planting methods and varieties after green up.(7) The biggest Bleeding intensity after heading early was DS, but weaker than MT and AT in the later; MT> AT in Yixiangyou 2115, AT>MT in Fyou 498.To35d after heading, the root bleeding intensity of DS, MT and AT decreased 84.7%,75.4% and 74.3% respectively than Od after heading in Yixiangyou 2115, F you 498 decreased 79.3%,75.9% and 74.3% respectively, the roots of DS aging faster than MT and AT.(8) The root traits and yield shows no significant correlation,at tillering stage and jointing stage, the total population root length, total population root volume, population root tips, population root dry weight, root-shoot ratio were significant or extremely significant negative correlation to the yield at heading stage, the population root dry weight and root-shoot ratio were significant negative correlation to the yield at maturity stage. Redundant root growth forms secondary database, and it’s not conducive to high yield,so reduce the redundant root growth has a positive effect on improving the yield of rice. The bleeding intensity decay rate showed significant negative correlation to yield after heading, therefore, take measures to slow pumping then agronomic root senescence has positive significance to improve yield.(9) The root trait of MT was most reasonable in these three planting methods. The average diameter of DS root was small, growth a lot of redundant roots after jointing stage, and aging fast after heading, it’s not conducive to high yield.The root of AThas a deep root distribution, but failed to obtain high yield because the root growth quantity was not enough,. This can be drawn, multiple and high activity root system is an effective guarantee for high yield. The rice root system of mechanized planting especially MT with high yield potential, can be adopted to further improve the population quality of mechanization sowing and transplanting to increase yield. |
