The Measurement and Prediction of Organ Growth in a Uniculm Barley

Ryle, Gilbert; Brockington, N.R.; Powell, C. E.; Cross, Beryl

doi:10.1093/oxfordjournals.aob.a084687

Cited by 16 publications

(4 citation statements)

References 6 publications

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“…However, not only the rate of maintenance respiration was underestimated in this model, but probably also the crop assimilation rate. Ryle, Brockington, Powell, and Cross (1973) used a value of 30 mg glucose per g dry matter per day to simulate growth of uniculm barley and obtained an encouraging agreement between experimental and simulated results.…”

Section: Table3 Maintenance Respiration Rates Obtained With Various mentioning

confidence: 80%

The Cost of Maintenance Processes in Plant Cells

1975

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The most important maintenance processes in plants are protein turnover and active transport processes to maintain certain ion concentrations in the cells. In this paper an attempt is made to calculate the total energy cost of these processes from what is known about their specific costs and what has been observed about their rates. Because of insufficient reliable data about rates of individual maintenance processes, only approximate values can be obtained.The average turnover rate of leaf proteins may be about 100 mg protein per g proteins per day at normal temperature in leaves assimilating at moderate light intensities. This process consumes 28-53 mg glucose per g protein per day, which equals 7-13 mg glucose per g dry weight per day in leaves. It is likely that the rates of protein turnover and of C0 2 -assimilation are related. The cost of maintaining ion concentrations is estimated to be about 6-10 mg glucose per g dry weight per day in leaves. The sum of these figures is lower than is indicated by measurements of maintenance respiration. One reason for the underestimation may be that the protein turnover rates used in the calculations apply to plants with lower photosynthetic rates than the plants in which the maintenance respiration was measured. Effects of water stress and salinity, temperature and other environmental factors on the rate of maintenance processes are discussed.The consumption of assimilates for maintenance of plant cells is a significant, negative factor in plant productivity. A better understanding of the maintenance processes may give a clue how to manipulate plant characteristics or the environment to reduce the amount of assimilates consumed in these processes. It is suggested that reduction in protein turnover rates may be one such manipulation.

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Section: Table3 Maintenance Respiration Rates Obtained With Various mentioning

confidence: 80%

The Cost of Maintenance Processes in Plant Cells

1975

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“…Although the magnitude of the respiratory losses varied between species, no clear and consistent distinctions could be drawn between them. In particular, maize and sorghum appeared to sustain very similar losses of carbon to those of the temperate species, which here also includes for comparison a uniculm barley and Lolium temulentum grown in the same conditions at an earlier date (Ryle et al 1973; G. J. A.…”

Section: I4c Lost In 24 H: Measurements Of That Which Entered Each Inmentioning

confidence: 76%

“…It is inevitable that losses are underestimated because the initial determina-' 5 5 tion of radioactivity is taken 25 min after leaves are first exposed to 14C0, and some respiratory loss presumably occurs in this period. In addition, measurements after 24 h only take account of respiratory losses arising from assimilate generated in the same diurnal period, although there will still be residual respiration from assimilate formed earlier (Ryle et al 1973). Furthermore, some refixation of respired 14C02 must occur both in temperate and tropical species although the present results provide no indication of the size of this component.…”

Section: ' 43mentioning

confidence: 99%

The utilization of recently assimilated carbon in graminaceous plants

Ryle

Powell

1974

Annals of Applied Biology

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S U M M A R YIsotopic carbon and infra-red gas analysis techniques were used to measure the following growth attributes in maize, sorghum, winter wheat and perennial ryegrass: the rate of entry of carbon into each main shoot leaf; the rate of translocation of leaf assimilate to meristems; the fraction of leaf and total shoot assimilate respired in one diurnal period; and the distribution of residual assimilate to new leaf, stem, axillary shoots and root.The two tropical plants possessed higher leaf assimilation rates and larger leaves than the temperate species, but their efficiency of translocation was only marginally superior in the experimental conditions. In all species, c. 25 yo of the assimilate generated in the 8-4 h photoperiod was respired in in the same diurnal period. Maize and sorghum partitioned a greater proportion of their total shoot assimilate to new leaf tissue at the main shoot apex and to root than wheat and ryegrass. On the other hand, wheat and ryegrass exported up to 30 yo of their assimilate to axillary shoots; in sorghum, little assimilate was translocated to axillary shoots, while in maize this activity was completely absent.Plant habit, as exemplified by the contrast between the annual, single-axis maize plant and the perennial, multi-tillering ryegrass plant, appears to be a reflexion of the pattern of assimilate distribution to areas of potential growth. With the exception of superior leaf assimilation rates in maize and sorghum, the four species showed no marked differences in respect of the production, transport and respiratory utilization of assimilates. 6 A P B 77 6-2

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“…A. Ryle (Ryle et al, 1973). The diagram represents the fate of carbon conipounds assimilated by a single leaf and the total model is built up of a number of such units, in parallel and interconnected, to imitate the carbon metabolism for the whole plant.…”

Section: Ivitliiti Systeitismentioning

confidence: 99%