The Redistribution of Stem Sugars in Wheat During Grain Development

Wardlaw, IF; Hk, Porter

doi:10.1071/bi9670309

Cited by 89 publications

(38 citation statements)

References 7 publications

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“…Although the early studies of Archbold (1942) on barley cast some doubt on the importance of stem reserves as a source of grain carbon it now appears that under well watered conditions these reserves, which include sucrose and a range of oligosaccharides, can be expected to account for 10-15 % of the weight of the grain at maturity (Wardlaw & Porter, 1967;Rawson & Evans, 1971;Austin et al, 1977). Blacklow, Darbyshire & Pheloung (1984) found that the maximum level of soluble carbohydrate occurred well into the grain development period (20-24 d after anthesis) and at this stage represented about 42 % of the stem dry weight.…”

Section: The Xylem As An Alternative Transport Systemmentioning

confidence: 99%

Tansley Review No. 27 The control of carbon partitioning in plants

1990

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Summary This review reports on the processes associated with carbon transfer and metabolism in leaves and growing organs and the role of long‐distance transport and vascular links in the regulation of carbon partitioning in plants. Partitioning is clearly influenced by both the supply and demand for photosynthate and is moderated by vascular connections and the storage capacity of the leaves and pathway tissues. However there appears to be little more than circumstantial evidence either that short distance transfer of carbon within either the source or the sink, or that long‐distance transport in the phloem, are limiting photosynthesis or growth directly. Although individual biochemical and physiological processes relating to photosynthesis and growth may be well understood, the factors primarily responsible for the control of carbon partitioning in plants have not been clearly identified. There is a need for a greater understanding of organ initiation and development (source and sink formation and potential size), the clear identification of whether growth is sink or source limited (including possible sink‐controlled photosynthesis) and a detailed assessment of the role of storage in buffering developmental and environmental changes in sink and source activity. Also more information is needed on the role of hormonal and nutritional factors in regulating source and sink activity (organ interactions not directly associated with carbon transfer).

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Section: The Xylem As An Alternative Transport Systemmentioning

confidence: 99%

Tansley Review No. 27 The control of carbon partitioning in plants

1990

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“…Furthermore, some estimates of movement to the grain are high as they do not allow for a proportion of the stem reserves to be transported to alternative sinks such as young developing tillers (Wardlaw & Porter, 1967). If a comparison is made later in kernel development between the rate of kernel filling and the mobilization of stem reserves over the same period, these reserves can account for 50% of the kernel requirements at this stage (Wardlaw & Porter, 1967 ;Apel & Na! tr, 1976 ;Bell & Incoll, 1990 ;Bonnett & Incoll, 1992).…”

Section: mentioning

confidence: 99%

Mobilization of fructan reserves and changes in enzyme activities in wheat stems correlate with water stress during kernel filling

2000

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Triticum aestivum (wheat) plants grown at a day : night temperature of 18 : 13mC from anthesis were held as well watered controls, or subject to either a mild (large pot volume) or a more severe (small pot volume) water stress by withholding water from the time of anthesis. Extracts from the peduncle (enclosed by the flag leaf sheath) and the penultimate internode were prepared to determine the activities of fructan exohydrolase and acid invertase and to assess the level of hexose sugars, sucrose and fructans. Measurements were made of ear and individual grain weights and stem fresh weight and dry weight. Plant water relations at the time of each sampling were determined as the flag leaf water potential and the water content of individual organs. Water stress resulted in a shorter duration of kernel filling, smaller kernels at maturity and an earlier loss of stem weight. There was an increase in stem fructose and a fall in fructan level that preceded the loss of dry matter associated with water stress. Coincident with the early fall in fructan content under water stress there was a rise in both fructan exohydrolase and acid invertase in the internodes of stressed plants. This correlation suggests that the conversion of fructans to fructose might have resulted from enzyme induction associated with water stress, but as this conversion occurs before the major export of reserves from the stem it might be only indirectly related to changes in the demand for reserves.

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“…Carbohydrates stored in the stem prior to anthesis may contribute 5-10% of final grain weight (Wardlaw and Porter 1967), or rather more in plants under stress (Asana and Joseph 1964;Yu et al 1964), but the major source of assimilate is current photosyr.thesis by the flag leaf, stem, and ear. The proportion of grain needs met by ear photosynthesis has been the subject of many investigations, reviewed by Thorne (1966).…”

Section: Introduotionmentioning

confidence: 99%

Photosynthesis and Respiration by the Flag Leaf and Components of the Ear During Grain Development In Wheat

Evans¹,

Rawson²

1970

Aust. Jnl. Of Bio. Sci.

210

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SummaryRates of photosynthesis and dark respiration of the ears and flag leaves of three varieties of wheat grown at 21 DC under a constant light intensity of 3200 f.c. were measured by infrared gas analysis twice weekly throughout the period of grain development. Measurements were made on both the intact ears and the separated grains and ear structures, in air and in a mixture of nitrogen plus 320 p.p.m. C02. Dry weights of the grains, ears, and main stems were also determined.Photosynthesis by the grains was near maximal at the light intensity measured inside the glumes, and nearly balanced the loss of C02 by dark respiration, until the grains ripened. Grain photosynthesis accounted for 33-42% of gross ear photo· synthesis. Ear photosynthesis, which was much higher in awned varieties, contributed up to 76% to total grain requirements during early growth, this proportion falling to a minimum of about 26% in Sonora (awned) and 15% in Gabo (unawned) during the period of most rapid grain growth, before rising again as grain growth slowed. Over the whole period of grain development the contribution to grain requirements by ear photosynthesis was 33% in Sonora and 20% in Gabo. The rate of photosynthesis by the flag leaf blades varied apparently in response to changes in the demand for assimilates. In Sonora, requirements by the ear during the period of most rapid grain growth were equivalent to 131 and 43 mg CO 2 per ear per day for growth and respiration of the grain respectively, while net photosynthesis at that time by the ear, flag leaf blade, and stem plus sheaths was 50, 126, and 42 mg C02 per day respectively. Photosynthesis by the ear and flag leaf blade alone could meet the needs of the ear at all times, and grain growth did not appear to be limited by the supply of assimilate.

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The Redistribution of Stem Sugars in Wheat During Grain Development

Cited by 89 publications

References 7 publications

Tansley Review No. 27 The control of carbon partitioning in plants

Tansley Review No. 27 The control of carbon partitioning in plants

Mobilization of fructan reserves and changes in enzyme activities in wheat stems correlate with water stress during kernel filling

Photosynthesis and Respiration by the Flag Leaf and Components of the Ear During Grain Development In Wheat

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