Response of sourcendash;sink relationship in soybean to temperature

摘要

The need for carefully defined conditions to demonstrate sink-source interaction was investigated using 'Biloxi' soybean grown under defined growth conditions. When the source area was reduced in seedlings by removal of the cotyledons and one primary leaf, the CO2uptake in the remaining leaf was increased at 24 deg;C but not at 27 deg;C. The 17 increase in the rate of CO2uptake at 24 deg;C was accompanied by an increase of assimilate export of about 5 over 24ensp;h. The effects on CO2uptake at 21 and 30 deg;C were smaller than at 24 deg;C but larger than at 27 deg;C. The percentage of assimilated14C that was translocated was also increased at 27 deg;C, but there was no accompanying stimulation of CO2uptake. Fruiting plants at 24 deg;C had close to double the CO2uptake rates of barren plants; whereas at 27 deg;C the rates were the same. Removing the pods reduced the CO2uptake at 24 deg;C to close to that of barren plants. Sink activity appeared to limit CO2uptake over a very narrow temperature range below optimum temperatures for growth, whereas at optimum temperatures CO2uptake appeared to limit growth.