Radicle elongation

TABLE III. Effect of Ferullc Acid (FA) on Radicle Elongation of Pre-germinated Grain Sorghum... 

Table VI. Time-course Study of the Effects of Chondrillasterol on Germination and Hypocotyl and Radicle Elongation in Mung Beans...

Radicle elongation was quite linear with time (r = 0.98, minimum). Pretreating the seed with DCM reduced early radicle growth, but by 96 h the sterol/DCM treated seed achieved radicle lengths equal to that of the H2O control and 30% more than those of DCM controls. The experiment was terminated at 96 h when space limitations in the petri dishes and near-anaerobic conditions during incubation began to interfere with seedling development. There were no secondary roots visible after 96 h. 

During seed imbibition, germination and radicle elongation, various... 

Camelina sativa I O-leaf wash stim d. radicle elongation in presence of -fix. bacteria 104... 

Several studies have reported the effects of BOA on plant growth at different concentrations. In this way, Aiupova et al. in 19791 found that concentrations of 1.5 to 8.2 Kg/ha BOA inhibited 50% radicle elongation of cucumber, oat, radish, and cabbage. An abnormal growth was also observed by Wolf et al.42 in velvetleaf seedlings when exposed to 5 mM BOA. 

ATPase activity was also studied by Friebe et al. in 1997.17 They correlated the BOA and DIBOA effects on radicle elongation of Avena sativa seedlings with their effects on the activity of plasma membrane H+-ATPase from roots of Avena sativa cv. Jumbo and from Vida faba cv. Alfred. They hypothesized that an alteration in the plasma membrane ATPase activity could be the reason for an abnormal nutrient absorption in plants exposed to hydroxamic acids, because of the role that this enzyme plays in the ion gradient and, therefore, in the ionic transport through plasma membrane. The results of this experiment showed a strong inhibition in the activity of this enzyme in the plasma membrane of chloroplast and mitochondria when it was exposed to BOA and DIMBOA. This alteration implies early interactions with the assayed hydroxamic acids. 

Phenoxazinone production was as well observed in incubation media of Secale cereale, but not in such of Vida faba and Triticum aestivum [180]. The compounds can be detected is well in incubation media of several dicotyledonous species [187]. Since surface sterilization of oat caryopses with NaOCl did not prevent phenoxazinone production, it is possible that the responsible microorganism(s) are located within the caryopses. Phenoxazinone itself has an inhibitory effect on oat radicle elongation, probably caused by intercalation of the phenoxazinone ring system to DNA, as it is known from the phenoxazinone ring system of the transcription inhibitor actinomycin D, an antibiotic produced by Strepto-myces species. 

Trewiasine (13), from the seeds of Trewia nudiflora (Eu-phorbiaceae), gives greater than 50% inhibition of radicle elongation with velvetleaf Abutilon theophrasti) (Malvaceae) (Powell and Spencer, 1988). 

Rutaceae 1,8-cineole, nonan-2-one, undecan-2-one radicle elongation of radish ... 

Isolated axes of peas are not dependent on the reserve material of the cotyledons during the initial stages of radicle elongation [17]. Reserves of carbohydrate, protein and fat in the radicle itself must be sufficient for these early events, and sucrose, raffmose and stachyose probably serve as sources of respirable substrate. But after these early events have passed, the further development of the root and shoot systems depends upon the contributions from the cotyledons. Their stored carbohydrate (and the other reserves) are hydrolysed and transported into the axis. It is not yet clear if the initiation of mobilization is actually controlled by the embryonic axis this is discussed fully in Chapter 7. We can say, however, that the subcellular changes in the cotyledons that precede and accompany reserve mobilization do need the presence of axis, at least over the first 48 h after the start of imbibition. 

Fig. 6.3. (A) Changes in the levels of starch and dextrin ( ), dextrin (o), free sugars (a) and extracted protein (v) in the cotyledons of the smooth pea (cv. Alaska). Time of radicle elongation was not reported in these studies. (B) Changes in starch phosphorylase (o) and amylase ( ) enzymes in cv. Early Alaska. After Juliano and Varner, 1969 [79]...

Fig. 6.27. Changes in protein (o), lipid (x), total chlorophyll a and b ( ), a-cellulose (hatched bar) and hemicellulose/starch (unhatched bar) content per cotyledon during germination and seedling development in Lupinus albus. R time of radicle elongation H time of hypocotyl expansion L time of expansion of first leaves and plumule. Germination is epigeal. Based on Parker, 1975 [115]...

Radicle elongation was a more sensitive measure than germination. Phytotoxicity decreased as the distance from rye shoot material to assay seeds increased. Generally, cress and lettuce were more sensitive indicators than the grass species tested. Phytotoxic compounds from shoots were water extractable. To evaluate the effect of plant part and quantity of residue, roots, shoots, or both were assayed at 0.0, 0.25, 0.5, 1.0, and 2.0 g/dish and placed 5 mm away from the assay seed. Similar amounts of paper towels were used as controls. Shoot tissue was about twice as toxic as root tissue. The data suggested that under field conditions, a... 

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