A comparison of the rate of maintenance respiration in some crop legumes and tobacco determined by three methods

Irving, D.E.; Silsbury, J.H.

A comparison of the rate of maintenance respiration in some crop legumes and tobacco determined by three methods

1987

Irving, D.E. | Silsbury, J.H.

Carbon exchange was measured on whole plants of field bean, lucerne, chick pea, kidney bean, pea and tobacco. The maintenance respiration rate was measured in three ways: (i) by allowing the CO2 efflux to decay in prolonged darkness to an asymptotic value which was then taken to be the maintenance value (the dark decay method); (ii) by plotting the dark CO2 efflux as a function of the net CO2 uptake over a range of irradiances and taking maintenance as the dark CO2 efflux when the net CO2 uptake was zero (the dynamic method); and (iii) by plotting the total CO2 uptake as a function of the growth rate and taking maintenance respiration as the CO2 efflux when the growth rate was zero (the zero growth rate method). The range of values for the maintenance coefficient over all species was from 1.6 to 2.1 per cent of the dry weight per day, 1.8 to 2.1 per cent and 2.7 to 2.9 per cent as determined by these three methods respectively. There was a linear relationship, common to all species, between the maintenance respiration rate (dark decay method) and dry weight, total nitrogen and the organic nitrogen content. The growth coefficient (0.69±0.01) was the same for field bean, chick pea and lucerne and was unaffected by the method of estimation. It was concluded that the dark decay method provided the best estimate of the minimal maintenance requirements in the plants studied.

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