Sugar concentration gradients of the sugar beet plant in relation to translocation

1973 ◽  
Vol 51 (10) ◽  
pp. 1733-1739 ◽  
Author(s):  
Michio Suzuki ◽  
D. C. Mortimer

An increasing sugar gradient in the rib, a decreasing gradient in the upper region of the petiole, and a sharp increase in the base of the petiole were found when transverse segments of the rib and petiole of a sugar beet leaf or the isolated vascular bundles as a whole were analyzed. The sugar concentration and the gradient pattern varied considerably with the leaf position in the ontogenic sequence. The proportion of assimilated 14C exported as sucrose was highest for leaves of intermediate age, which were at the nearly mature stage. Mature and old leaves exported less 14C and young leaves, which had a high sugar concentration in the blade and a sharply decreasing gradient in the petiole, exported very little. Analysis of vascular bundles in the petiole which serve the tip and basal regions of the blade after 14CO2 incorporation into the blade indicated that a much larger amount of 14C-sucrose entered into and moved through the basal bundle than into and through the tip bundle.

Author(s):  
K. E. Reay

Abstract A description is provided for Xanthomonas campestris pv. graminis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Lolium italicum, L. multiflorum, L. perenne, Dactylis glomerata, Festuca pratensis, and Trisetum flavescens. Single cases of natural infection of Agropyron repens, Phalaris arundinacea and Phleum pratense are also recorded (62, 241), but their status in the natural host range is unknown. In inoculation tests (Egli et al., 1975; Egli & Schmidt, 1982) the following were highly susceptible: Alopecurus pratensis, Dactylis glomerata, Festuca arundinacea, F. pratensis, F. rubra, Lolium loliaceum, L. multiforum, L. parabolicae, L. perenne, L. remotum, L. temulentum, Phleum arenarium and P. bertolonii. Showing much less susceptibility were Agrostis alba, Arrhenatherum elatius, Phleum alpinum, P. phleoides, P. pratense, Poa annua, P. compressa, P. fertilis, P. memoralis, P. pratensis and P. trivialis. Leyns et al. (61, 6162) found that Agrosas tenuis and Festuca ovina were moderately susceptible when inoculated. Egli et al. (1975) recorded doubtful symptoms on Hordeum vulgare and Triacum aestivam on inoculation, but consider that they are unlikely to be naturally infected. DISEASE: Bacterial wilt of forage grasses. Symptoms usually first noticed at the heading stage, when young leaves curl and wither, and shoots remain stunted or may die. Other plants will continue to make poor growth and produce small, distorted inflorescences. Chlorotic and necrotic zones form on the older leaves along long stretches of vascular bundles, often extending into the sheaths. Bacterial streaming may be seen under the microscope from the cut ends of vascular bundles of infected tissue mounted in water. GEOGRAPHICAL DISTRIBUTION: CMI Map 533, ed. 1, 1979 lists France, Germany, Switzerland and Wales, to which must be added Scotland (63, 2925), Belgium (61, 4199), Netherlands, Norway (62, 241), and New Zealand (62, 241). Possibly in USA (IL; 61, 5045) though this disease is currently attributed to a Rickettsia- like organism. TRANSMISSION: Within the crop transmission is presumed to be by the blades of mowing machines.


2019 ◽  
Vol 99 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Marija Saric-Krsmanovic ◽  
Dragana Bozic ◽  
Ljiljana Radivojevic ◽  
Jelena Gajic Umiljendic ◽  
Sava Vrbnicanin

The physiological and anatomical impact of field dodder (Cuscuta campestris Yunck.) on alfalfa and sugar beet was examined under controlled conditions. The following parameters were checked: physiological — content of pigments (chlorophyll a, chlorophyll b, and carotenoids) and mineral nutrients: nitrogen, phosphorus, potassium, and percent of organic and mineral nutrients; and anatomical — thickness of the epidermis and cortex, diameter of the stem and central cylinder of alfalfa plants, diameter of tracheids and phloem cells, area of xylem and phloem, and hydraulic conductance of petiole bundles in petiole vascular bundles of sugar beet plants. Leaf parameters were also measured on both host plants: thickness of upper and underside leaf epidermis, thickness of palisade, spongy and mesophyll tissue, and diameter of vascular bundle cells. Pigments content and anatomical parameters were measured 7, 14, 21, 28, 35, and 42 d after infestation (DAI), while mineral nutrient contents were determined 20 and 40 DAI. Field dodder caused a significant reduction in pigments content in infested alfalfa (15%–68%) and sugar beet plants (1%–54%). The results obtained in this study confirmed that this parasitic flowering plant has a strong effect on most anatomical parameters of the stem and leaf of alfalfa and leaf and petiole of sugar beet. Also, it was revealed that field dodder increased the contents of N, P2O5, K2O, and organic nutrients in infested alfalfa plants, while infested sugar beet plants had higher contents of N and organic nutrients compared with non-infested plants.


2012 ◽  
Vol 26 (2) ◽  
pp. 177-182 ◽  
Author(s):  
Darren E. Robinson ◽  
Kristen E. McNaughton

Trials were established in 2007, 2008, and 2009 in Ontario, Canada, to determine the effect of soil residues of saflufenacil on growth, yield, and quality of eight rotational crops planted 1 yr after application. In the year of establishment, saflufenacil was applied PRE to field corn at rates of 75, 100, and 200 g ai ha−1. Cabbage, carrot, cucumber, onion, pea, pepper, potato, and sugar beet were planted 1 yr later, maintained weed-free, and plant dry weight, yield, and quality measures of interest to processors for each crop were determined. Reductions in dry weight and yield of all grades of cucumber were determined at both the 100 and 200 g ha−1rates of saflufenacil. Plant dry weight, bulb number, and size and yield of onion were also reduced by saflufenacil at 100 and 200 g ha−1. Sugar beet plant dry weight and yield, but not sucrose content, were decreased by saflufenacil at 100 and 200 g ha−1. Cabbage plant dry weight, head size, and yield; carrot root weight and yield; and pepper dry weight, fruit number and size, and yield were only reduced in those treatments in which twice the field corn rate had been applied to simulate the effect of spray overlap in the previous year. Pea and potato were not negatively impacted by applications of saflufenacil in the year prior to planting. It is recommended that cabbage, carrot, cucumber, onion, pepper, and sugar beet not be planted the year after saflufenacil application at rates up to 200 g ha−1. Pea and potato can be safely planted the year following application of saflufenacil up to rates of 200 g ha−1.


2020 ◽  
Vol 71 (12) ◽  
pp. 3463-3474
Author(s):  
Dario Constantinescu ◽  
Gilles Vercambre ◽  
Michel Génard

Abstract We develop a model based on the biophysical representation of water and sugar flows between the pedicel, fruit xylem and phloem, and the fruit apoplast and symplast in order to identify diurnal patterns of transport in the pedicel–fruit system of peach. The model predicts that during the night water is mainly imported to the fruit through the xylem, and that fruit phloem–xylem transfer of water allows sugar concentrations in the phloem to be higher in the fruit than in the pedicel. This results in relatively high sugar transport to the fruit apoplast, leading to relatively high sugar uptake by the fruit symplast despite low sugar concentrations in the pedicel. At midday, the model predicts a xylem backflow of water driven by a lower pressure potential in the xylem than in the fruit apoplast. In addition, fruit xylem-to-phloem transfer of water decreases the fruit phloem sugar concentration, resulting in moderate sugar uptake by the fruit symplast, despite the high sugar concentration in the pedicel. Globally, the predicted fruit xylem–phloem water transfers buffer the sugar concentrations in the fruit phloem and apoplast, leading to a diurnally regulated uptake of sugar. A possible fruit xylem-to-apoplast recirculation of water through the fruit phloem reduces water lost by xylem backflow at midday.


1982 ◽  
Vol 9 (4) ◽  
pp. 449 ◽  
Author(s):  
HM Rawson ◽  
NC Turner

Five cultivars of sunflower with different durations to anthesis were grown in the field either entirely on stored soil moisture (DRY), irrigated frequently throughout growth (WET), or transferred from the DRY to the WET regime at 44 days (REC 1) or at 54 days from sowing (REC 2). The expansion patterns of all leaves were followed with a view to determining which leaves responded when stress was relieved. Cultivars differed in their ability to recommence leaf expansion after water was applied to DRY crops, but any differences were related to the stage of plant development reached when water was applied. Thus in the REC 1 treatment, no leaves of early cultivars equalled the areas achieved in equivalent leaves in the WET regime, whereas the latest cultivar generated individual leaves which were 60% larger than equivalent leaves in the WET treatment. In the REC 2 treatment, few leaves of the early cultivars reached significantly larger areas than equivalent leaves in the DRY while all leaves above node 12 in the latest cultivar exceeded those in the DRY regime. Examining the data in terms of the age of leaves in the profile when the REC 1 and REC 2 treatments were applied showed that, regardless of cultivar, all leaves which were less than 15 days old (age 0 = leaf emergence) had some capacity for renewed expansion when water was applied. However, primordia which still had 15 days to go before they emerged as leaves had the greatest capacity for expansion to a potential size, and this capacity decreased progressively over their next 30 days of aging. Leaf age profiles did not explain all the difference in renewed expansion potential among cultivars: a leaf position factor at the time of water application was almost as important. Thus, the closer that leaves were to the head, the less was their capacity for renewed expansion regardless of their age. In order to achieve larger areas when water was applied, old leaves increased their duration of expansion while young leaves increased their rate of expansion. It is concluded that cultivars do not differ in their ability to 'recover' leaf area upon application of water except by virtue of their different durations to anthesis.


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