Characteristics Of Yield Components, Plant Type And Canopy Structure Of Super-High-Yielding Wheat Genotypes

To try to find out the characteristic of the yield components, plant type and canopy structure of super - high - yielding wheat genotypes, and to resolve the problems related to them, a systemic research was conducted with the data of yield characters of the super - high - yielding wheat genotypes presented and the data of our experiments in 1998—2000.1. The average of the numberof the spike per hm², number of grains per spike, and the 1000-grain weight for the super-high-yielding genotypes selected last times in Huanghuai winter wheat area were 606.2 (ten thusand),and the big ,middle and snail spike type amoun them were respectively 471.7, 48.3, and 48.1; 616.3,37.9 and 44.9; 715.3, 34.1 and 40.7. The trend of chang curv of the number of spikes per unit area was as single kurtosis as the rising of the yield level for the genotypes , and the maximum valu was at the level of yield, for the transitial super---high---yielding genotypes, and indecresed a littl for the super-high-yielding genotypes ;and it was trend to rise as a straight line for the number of grains per spike and the 1000-grain weight .The effect of the correlation and the contribution strainghtly to the yield were the most for the number of spike per unit, and the main effactor inhibitting to the rising of the yield was the insuficience of the number per unit area. The effects of the compnents on the yield for different types were respectively: the most consignifacant was the number of spike per unit for the big and the middle genotypes , the second was the number of grains per spike , and the smallest was the ; the most signifacant was the number of spike per unit, the smallest but one was the 1000-grain weight for the small spike genotypes.2. The best regression equations of yield components combination for the large, middle and more ear type of super-high-yielding tentypes were established as follow:y_{large ear} =131213.6 + 233.8199x₁-0.1680x₁² - 11599.5x₂ + 174.4179x₂²-202.231x₃-1.03712x₃²y_{middle ear} =-73797.1 + 91.7240x₁-0.0655x₁²-116.2486x₂ + 4.5679x₂² +2143.6020x₃-22.7180x₃² 2-551197x+61266x2y_{more ear}=26170.49-65.5308x₁ + 0.0713x₁²-551.197x₂+6.1266x₂² + 414.2744x₃-4.1139x₃²The model of yield component combition for the three kinds of ear type under the level of 9000¹0500, 10500¹2000, 12000¹3500 and 13500¹5000 were established modeled.3. The characteristic of the stem structure of the super-high-yielding genotypes were: 79.1 ± 6.1cm for stem hight; 1 : 3 : 2 : 1.5 : 0.6 for the length ratio of thespike and 5 nods (starting from top) composed the stem; 0.312, 0.393, 0.417, 0.402 and 0.386 cm for the stem diameter of the 5 nods; 3 .' 1 ' 0.5 : 0.5 for the dry biomass of the spike, stem, sheath and leave the composing index of the plant hight was not tally with the "golden cut value"0.618, and it>0.618 at the base and<0.618 at middl and top; a nearly the same value of 0.53 for the composing index of the all sheathes; the sheath length/nod length of No.l and No.2 of the top were higher than that of high-yielding genotype, and that of the other three nods alike it; this made the plant hight reduce by 5 cm as compared with that of the high-yielding genotypes, but it maintained a good photosynthesis as the decreasing of the plant hight.4. The buffering ability index of the super-high-yielding genotype was greater than that of general high-yield one, and which indicated that it had stronger buffering ability to density, and this was important base of high-yielding for super-high-yielding genotype, and it could be as a important selecting index for plant characters.5. Except having common characteristic of the plant type structure, the super-high-yielding genotype have formed varied plant type structures because of numerous genes controlling of the plant characters and the complicating of their's reaction. Three kinds of typical of plant type structures were put forward by us in this paper, and they are—the loose plant type with small leaves, short stem, and middl-high spike; the drop leaves plant type with middl leaf, middl-high stem, and big spike; and the compact plant type with large leaves, middl-short stem.6. The main characteristics of canopy structure for the super-high-yielding genotype were: 80.3 +8.8cm of the canopy structure hight; 8.6cm of the spike length; higher leaf area index and longer time for maintaining of the green leaves; a moderat for size or proportion, higher content of clorophyll, stronger physiologic activity, and higher photosynthesis rate for the three leaves at the top, grain weight / leaf area, dry biomass for unit area and harvest index.7. In addition to having common high efficiency in photosynthesis, super-high-yieleing genotype's canopy structure of the characters had a significant difference as the varing genotypes, and this showed that the canopy structure of the super-high-yielding genotype were diversity. In view of the above, it was put forward that three typical kinds of idea canopy structures-the loose structure type with small leaves, short straw, middl-big spike and heavy density; the scattered density type with large leaves, middl-short straw, big spike and compact plant type; and the middl density type with middl leaves, middl-high straw, and big spike. At the same time, the three kinds of canopy structure were compared, and the best idea canopy was the first kind.