| A split plot field experiment was conducted using Fyou 498 as material during year 2012-2013 in Huapai village, Pixian, Sichuan province. The tillering and panicle formation pattern, plant-type characteristics and lodging resistance of mechanized direct-seeding, mechanized transplanting and artificial transplanting under different seedling number and sowing date treatments were studied. Effects of mechanized planting methods on tillering characteristics, population structure and panicles traits were illustrated. Then it could provide theoretical and practical basis for designing high-yield planting techniques of indie a hybrid rice of mechanized planting. The main results were as follows:(1) The sources of panicles were different significantly among different planting methods. The major and stable contribution to yield was from primary tillers group and the proportion of primary tillers group yield, ranging from 58.67% to 63.82% among different planting methods. The contribution to yield from main stem was significantly different with the highest in mechanized direct-seeding and the lowest in artificial transplanting. Yield of secondary tillers group was much lower in mechanized direct-seeding than in mechanized and artificial transplanting. Leaf 1 to leaf 4 in mechanized direct-seeding, leaf 3 to leaf 6 in mechanized transplanting and leaf positions of 1,2,4,5 and 6 in artificial transplanting were the superior leaf positions. Their contributions to yield were 70.51%, 73.83% and 76.81%, respectively. The main stem and primary tillers in low and middle earbearing leaf positions had larger branches, spikelets per panicle, grain weight and grain weight per panicle among three planting methods. The number of earbearing tiller branches and spikelets per panicle of secondary tillers and primary tillers in high earbearing leaf positions were fewer, so their panicles were small.(2) The tillering and panicle formation pattern was different for different planting methods which had a changing trend with a single peak for mechanized direct-seeding and transplanting and with two peaks for artificial transplanting. Tillers of mechanized direct-seeding had early and fast emergence and the primary tillers group emerged from leaf 1 to leaf 8, among which tillers from leaf 1 to leaf 4 had higher emerging rate and more panicles, secondary tillers group earbeared mainly in 1/1 and 1/2. Tillers of mechanized transplanting had relatively later, small and concentrated emergence, the primary tillers group mainly emerged from 3/0 to 8/0, among which leaf position of 3/0 to 6/0 had higher rates of panicle formation, secondary tillers group emerged mainly in 1/3, 1/4,2/4,1/5, but earbeared mainly in 1/3 and 1/4. The number of tillering leaf positions of artificial transplanting was more and tillering time was longer in seeding bed and field. The primary tillers group mainly emerged from leaf 1 to leaf 8 besides leaf 3, among which the tillers of leaf 1, leaf 2, leaf 4, leaf 5 and leaf 6 had higher earbearing percentage, secondary tillers group emerged mainly in 1/1,2/1,3/1,1/2,2/2, but earbeared mainly in 1/1,2/1 and 1/2. The number of tillering and earbearing leaf position decreased with delaying sowing date.(3) The traits of plant-type differed markedly among three planting methods. The length, width and leaf distance of top three leaves as well as blade tangent and drooping angle were larger under mechanized direct-seeding and transplanting. The top three leaves were erect with proper leaf area in the treatment of artificial transplanting. Plant height and leaf size of top three leaves were significantly larger in the treatments of mechanized direct-seeding and transplanting than in that of artificial transplanting. However, specific leaf weight, panicles per plant and total leaves were greater under artificial transplanting than under mechanized planting. For culm angle, spikelets and grain weight per panicle, the ranking orders of treatments were mechanized transplanting> artificial transplanting> mechanized direct-seeding. Leaf area increased with delaying sowing date or decreasing seedling number per hill and late sowing reduced the ratio of grain number to leaf area, panicles per plant, spikelets per panicle and seed-setting rate markedly. A significantly positive correlation was observed between grain weight per panicle and length, width, inserted height of leaf and plant height. There were significant correlations between some traits of plant type and yield as well as its components. The notable characteristics of high-yield plant type in mechanized planting were proper plant height, length of top three leaves, LAI and culm angle. Meanwhile, the larger leaf width, specific leaf weight, leaf distance of top three leaves, erect leaves, adequate panicle number and large panicles were critical to high yield.(4) The lodging index of rice plants was different significantly among three planting methods and lodging resistance was significantly higher in the treatment of artificial transplanting than that of mechanized planting. In the treatment of artificial transplanting, plant height and gravity center height were lower, and basal internodes was short, thick and sturdy, culm type index and dry weight per unit length of internode were larger, the contents of cellulose, lignin, soluble sugars and K were larger, and the bending moment was lower, so lodging resistance was high. Plant height, basal internodes length and contents of N and P in mechanized direct-seeding and transplanting were larger. Plumpness status and contents of cellulose, lignin, soluble sugars and K were reduced. The lodging indexes were larger as its larger bending moment. Plant height and internonde length increased and the internode diameter and thickness, plumpness status, contents of cellulose, lignin, soluble sugars and K and breaking moment lowered, lodging indexes were increased significantly with delaying sowing date. Lodging index positively correlated to plant height, gravity center height, internode length, bending moment and contents of N and P, and negatively correlated to internode diameter and thickness, culm type index, dry weight per unit length of culm, and contents of cellulose, lignin, soluble sugars and K. The breaking moment was negatively correlated with panicles, and positively and significantly with spikelets per panicle, grain weight per plant and grain yield. Lodging index was negatively with spikelets per panicle and grain yield. The bending moment was larger in lower internodes than in higher internodes, with relatively small changes in basal internodes. That’s why the lower internodes were lodging-susceptible.In conclusion, tillers emergence in the treatment of mechanized direct-seeding was early and fast and its tillers from main stem and leaf 1 to leaf 4 which had higher percentage of earbearing. The total leaves, percentage of emerging and earbearing of secondary tillers and panicles per plant were low. The secondary branches and its No. of spikelets and grain weight per panicle were low as well. The number of effective panicles should be increased for increasing yield. The length and width of top three leaves were large in low seedlings treatment as well as drooping angle which were not favor for accepting sunshine for lower leaves. The top three leaves were erect with proper leaf area in high seedlings treatment and its internode length and diameter were better. Its yield was higher relatively with lodging resistance not reduced significantly. Panicles per plant and lodging resistance were decreased notably with delaying sowing date as the basal internodes became longer, thinner and individuals got worse. Thus, indica hybrid rice should be sowed early as the time allows with 3-4 seedlings per hill approximately in mechanized direct-seeding and seedlings per hill should be increased properly with delaying sowing date. We should improve earbearing tiller percentage and individuals quality for mechanized direct-seeding by developing the quality of cultivation and seeding, drying field in time and optimizing fertilizer management.Leaf 3 to leaf 6 of mechanized transplanting were the superior leaf positions as leaf 1 and leaf 2 were missed easily. Panicle length, primary and secondary branches and its spikelets per panicle of lower leaf positions were larger in mechanized transplanting. The culm became thinner and its lodging resistance lowered significantly when population was excessive. Panicles and spikelets were larger while seedlings per hill and effective panicles were appropriate. The leaf area and drooping angle of top three leaves were large and its yield was low because effective panicles were not enough in low seedlings treatment. Spikelets per panicle, seed-setting rate, panicles per plant, grain weight per panicle and lodging resistance were reduced significantly in late sowing date treatment. Panicles and spikelets were combined with 2-3 seedlings per hill in mechanized transplanting and we should transplant early after harvesting wheat or rapeseed. In order to improving yield potential and form large panicles, we should make use of the superior leaf position tillers for mechanized transplanting by developing the quality of seedlings and transplanting. |
