A SYSTEMS APPROACH TO THE PHYSIOLOGICAL BASIS FOR HYBRID VIGOR

THE PHYSIOLOGICAL-THERMODYNAMIC BASIS FOR HYBRID VIGOR (YIELD HETEROSIS) IN CORN AND OTHER CROPS IS NOT PRESENTLY KNOWN. THUS, DEVELOPMENT AND SELECTION OF INBRED LINES FOR HYBRID VIGOR RELIES ON GENERAL KNOWLEDGE ABOUT HETEROTIC GROUPS, NUMEROUS CROSSES, AND EXTENSIVE FIELD TESTS TO ACHIEVE THE INDUSTRY AVERAGE OF 1 TO 2 BU/ACRE/YR INCREASE IN YIELD. EACH COMMERCIAL HYBRID MAY COST FROM $1.2 TO $2.5 MILLION OVER AN 8 TO 10 YEAR PERIOD. WE PROPOSE TO ADDRESS THIS PROBLEM WITH A SYSTEMS APPROACH BASED ON A COMBINATION OF NON-DESTRUCTIVE, IN-VIVO METHODS UTILIZING THE SHORT-LIVED ISOTOPE TRACER (11)CO2 TO MEASURE A THERMODYNAMICALLY COMPLETE SET OF PHYSIOLOGICAL CHARACTERISTICS CONTROLLING CARBON ASSIMILATION AND ALLOCATION IN INBRED LINES OF CORN FROM SELECTED HETEROTIC GROUPS WHOSE HYBRIDS EXPRESS DIFFERENT LEVELS OF VIGOR. THERESULTING PROFILES OF POTENTIALLY COMPLEMENTARY PHYSIOLOGICAL CHARACTERISTICS FOR EACH INBRED LINE WOULD AID IN DEVELOPING OR SELECTING FOR DESIRED TYPES OF COMBINING ABILITY. ALSO, BY TESTING EACH PLANT UNDER DIFFERENT ENVIRONMENTAL CONDITIONS, ONE CAN SELECT FOR IMPROVED RESPONSES TO DROUGHT, ELEVATED CO2, POLLUTANTS, ANDOTHER STRESSES. SIGNIFICANT CORRELATIONS BETWEEN THESE PHYSIOLOGICAL CHARACTERISTICS AND YIELD WOULD ENABLE BREEDERS TO INCREASE NUMBER AND PERFORMANCE OF SUPERIOR HYBRIDS FOR A GIVEN AMOUNT OF BREEDING AND TESTING EFFORT, AND THUS GAIN COMPETITIVE ADVANTAGES IN THE MARKET.