Significance of Photosynthate Produced at Different Stages of Growth as Carbon Source for Fruit Filling and Seed Reserve Accumulation in Lupinus angustifolius L

Abstract

Growth and reproductive phenology of field-grown, non-irrigated L. angustifolius (cv. Unicrop) were studied by periodic sampling of plants. Anthesis occurred when plant carbon content was only 15% of its final maximum. Flowering and the main periods of pod growth and seed filling took place, respectively, 0-6, 5-9 and 8-12 weeks after anthesis. Over 80% of the plant's gain of carbon in dry matter occurred 0-8 weeks after anthesis, after which drought-induced defoliation curtailed dry matter accumulation. 14CO2 was fed to selected plants at weekly intervals over the period 0-12 weeks after anthesis and time courses of transfer of 14C-labelled assimilates to fruits were assayed non-destructively by periodic sampling of phloem sap from fruits. Average specific radioactivity of carbon of phloem sap samples from primary, secondary and tertiary fruits of each feeding treatment were compared with specific 14C activities of the respective fruits harvested at maturity. The agreement between data was very close with times of 14CO2 feeding up to 8 weeks after anthesis. With later times of feeding, average specific radioactivity of phloem sap was higher than that of fruits as labelled sap was collected for only the latter part of the life of the fruit and before the fruit had accumulated unlabelled carbon. Carbon from photosynthate fed before or during flowering contributed mainly to protein of the seed, that from photosynthate formed during fruiting mainly to non-protein seed components. Distribution of 14C between amino and non-amino compounds of fruit phloem sap of plants fed 14CO2 at anthesis or in late fruiting reflected this effect. Estimates of contributions of carbon of photosynthate to fruits suggested that only 2% of the fruit's carbon came from photosynthesis before flowering and only 3 % from photosynthesis 0-3 weeks after anthesis, while 18, 28 and 23% came from photosynthate formed respectively 3-6, 6-9 and 9-12 weeks after anthesis.

Contribution of Remobilized Total Dry Matter to Soybean Yield

“…Based on patterns of label accumulation and loss from these organs (mainly leaf blades), the authors supported the many studies cited above that remobilization occurred between mid seed filling to senescence. Similar results were reported for cowpea (Pate, Atkins, & Perry 1980). Although the Yamagata, Kouchi, and Yoneyama (1987) study determined the percentage of remobilized yield for greenhouse conditions, field studies addressing this issue are not available.…”

Distribution of nitrogen absorbed during different times of growth in the plant parts of wheat and contribution to the grain amino acids

“…The amino acid composition of the phloem sap of wheats has not been reported, but the existence of histidine, lysine, threonine, serine, leucine, and valine in the phloem sap of white lupin (17), and valine, lysine, histidine, and arginine in the phloem exudates of rice plants (3) has been recorded, though the major N forms in these phloem saps were also amides. Arecent report by PATE et al (18) on lupin indicates that high 14C specific activities were observed in valine, lysine, aspartic acid, and isoleucine in the fruit phloem sap 9-10 weeks after 14C0 2 feeding, while HC label was found only in serine and asparagine immediately after 14C0 2 feeding. The wide spread of HC label in the phloem amino acids in the former may suggest that these amino acids are derived from protein breakdown.…”

Quality and Distribution of Assimilates within the Whole Plant of Lupines (L. albus and L. mutabilis) Influenced by Water Stress

“…The plants respond to ws by investing in the first place in the development and maintenance of vital functions and less in the synthesis of new structural carbohydrates. Nevertheless, starch depletion was not accompanied by a sharp increase in glucose or hexose derivatives (Pate et al. 1980, Jenner et al.…”