Growth Properties and Biomass Production in the Hybrid C4 Crop Sorghum bicolor.
Hybrid vigor (heterosis) has been used as a breeding technique for crop improvement to achieve enhanced biomass production, but the physiological mechanisms underlying heterosis remain poorly understood. In this study, to find a clue to the enhancement of biomass production by heterosis, we systemically evaluated the effect of heterosis on the growth rate and photosynthetic efficiency in sorghum hybrid [Sorghum bicolor (L.) Moench cv. Tentaka] and its parental lines (restorer line and maintainer line). The final biomass of Tentaka was 10-14 times greater than that of the parental lines grown in an experimental field, but the relative growth rate during the vegetative growth stage did not differ. Tentaka exhibited a relatively enlarged leaf area with lower leaf nitrogen content per leaf area (Narea). When the plants were grown hydroponically at different N levels, daily CO2 assimilation per leaf area (A) increased with Narea, and the ratio of A to Narea (N-use efficiency) was higher in the plants grown at low N levels but not different between Tentaka and the parental lines. The relationships between the CO2 assimilation rate, the amounts of photosynthetic enzymes, including ribulose-1,5-bisphosphate carboxylase/oxygenase, phosphoenolpyruvate carboxylase and pyruvate phosphate dikinase, Chl and Narea did not differ between Tentaka and the parental lines. Thus, Tentaka tended to exhibit enlargement of leaf area with lower N content, leading to a higher N-use efficiency for CO2 assimilation, but the photosynthetic properties did not differ. The greater biomass in Tentaka was mainly due to the prolonged vegetative growth period.
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555 Japan CREST, JST, Gobancho, Chiyoda-ku, Tokyo, 102-0076 Japan.
Youshi
Y
Tazoe
Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan.
Takashi
T
Sazuka
Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan.
Miki
M
Yamaguchi
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033 Japan.
Chieko
C
Saito
Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501 Japan.
Masahiro
M
Ikeuchi
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555 Japan.
Keiichi
K
Kanno
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555 Japan.
Soichi
S
Kojima
Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan.
Ko
K
Hirano
Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan.
Hideki
H
Kitano
Faculty of Agriculture, Education and Research Center of Alpine Field Science, Shinshu University, Nagano, 396-0111 Japan.
Shigemitsu
S
Kasuga
Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501 Japan.
Tsuyoshi
T
Endo
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033 Japan.
Hiroo
H
Fukuda
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555 Japan CREST, JST, Gobancho, Chiyoda-ku, Tokyo, 102-0076 Japan makino@biochem.tohoku.ac.jp.
Amane
A
Makino
D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D006823:Hybrid Vigor; D009584:Nitrogen / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D012274:Ribulosephosphates / Q000378:metabolism; D045868:Sorghum / Q000235:genetics / Q000254:growth & development* / Q000502:physiology
D010940:Plant Proteins; D012274:Ribulosephosphates; D002734:Chlorophyll; D002245:Carbon Dioxide; C001933:ribulose-1,5 diphosphate; D010730:Phosphoenolpyruvate Carboxylase; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
Biomass; C4 plant; Carbon isotope discrimination; Heterosis; Hybrid; Sorghum