Germination imbibition

Seeds can be placed in water, and as imbibition occurs, the materials lost from seeds can be collected and analyzed qualitatively and quantitatively (10). Once germinated, seeds are commonly placed on some form of grid or support above the nutrient solution and, as the roots grow in the nutrient solution, it can be collected at intervals and the rhizodeposits analyzed. Seeds are often surface-sterilized to prevent utilization or alteration of the materials derived from the seed by contaminating microorganisms (e.g.. Ref. 11). 

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

When a spore prepares itself for germination, it loses its refractility,Which coincides with an imbibition of water. This stage is associated with a loss in heat resistance, stainability, and dry weighit. Later the spore coat breaks, followed by the emergence from the spore case of a new germ cell which eventually matures into a vegetative cell. 

Procedure Germination conditions were 25 1°C under continuous fluorescent light of 25 mE m 2 sec-1. Seed germination was monitored by observing the seeds directly in the Petri dishes with a stereomicroscope. They were considered germinated, when the radicle had protruded through the seed coat. Seeds sampled at different times after the beginning of imbibition were used for microscopy studies. 

Imbibition of the dry seeds is initiated by placing them in the airlift tank filled with water. Later, nutrients and other substances can also be added. For example, KN03 cannot be added any earlier than 6 hours after the start of germination, or it will inhibit sprout growth. 

A developing embryo produces ABA, which incepts and maintains mature seed dormancy. Germination begins with the uptake of water by imbibition of the dry seed and is followed by embryo expansion. Usually, it is considered complete when the radicle is through all the covering layers. There is still controversy whether... 

During imbibition of whole tea seeds (6 days) two purine alkaloids, caffeine and theobromine, did not decrease in the seed coats and there was no increase in the seeds. In parallel with and after the breaking seed coats there was a gradual release of caffeine from coats of germinating seeds. By contrast, when the seed was freed from the outer seed coat and soaked, imbibition of the seed required only two days and simultaneously caffeine was released from the inner seed coat. 

The seed coat of tea regulates imbibition of tea seed (Figure 2) and releases caffeine during germination (Figure 3). These processes may be dependent upon... 

Figure 4. Levels of Caffeine (A,A) and Theobromine (O, ) in Seed Coats (A, ) and Cotyledons (A,0) of Tea during Imbibition and Early Germination.

Pre-germination. Surface-sterilized seeds of the wheat genotypes were each soaked in sterilized water for imbibition of water in light at 25°C for 24 h and then rinsed with fresh sterilised water. The wheat seeds were then incubated in light at 25°C for another 24 h. 

Radish seeds were treated with RO fraction at dilutions 1 8, 1 10 and 1 14 as described above and were processed for electron microscopy 46 h after the start of the treatment. Roots from control seeds, moistened with distilled water, were fixed after 2, 16 and 46 h in order to get several developmental stages as references for treated seeds. The root apex, about 1 mm long, was cut under a dissecting microscope from at least 10 seeds and fixed in the primary fixative for 2 h at room temperature under mild vacuum. Since the control seeds had not yet started germination after 2 h imbibition and nearly 100% of the seeds treated with 1 8-diluted had not germinated after 46 h, in these two cases the seed integument was cut open with a razor blade in order to dissect the root. 

Table 6.4. Effect of Flooding Soybean Seeds After Imbibition and Impact Damage on Mean Germination Percentage After 1 to 4 Days...

After the imbibition, the initial growth (germination process) is followed by substance conversion from the hydrolysed seed substance into biosynthesised substance of the root and shoot, since the young plant is not capable to produce its own substance by photosynthesis (chlorophyll has not been synthesised or it quantity is under a critical... 

The rate of use of lAA by 5-day-old (24 h imbibition, 96 h germination) seedlings is discussed elsewhere in this volume. We estimate the rate of use of lAA as 5 pmol shoof h" and 50 pmol kernel h [9, Nonhebel, this volume]. This estimate is based upon many experiments involving both the rate of lAA production by the tip, the rates of upward transport and hydrolysis of lAA conjugates, and the rate of lAA oxidation. The agreement between these various experiments is better than order of magnitude and we believe are correct to better than fivefold. 

Medium for Plant Growth. Soil anchors the roots of a plant (or shoot) and holds its above-ground parts in place. Pore spaces between soil solids supply oxygen to the roots of established plants or to germinating seeds during respiration. Soil pores also store water, which is supplied to the roots for absorption or to the seeds for imbibition. Moisture in the pores minimizes soil temperature fluctuations in the rhizosphere. As a result, soil serves as an insulator that protects plant roots from extremely hot and cold conditions. 

By 6 days post-imbibition, seeds from 77825-83 sorted into three categories (a) 18% of the seeds germinated and grew into normal seedlings indistinguishable from standard canola, (b) 69% of the seeds germinated but their cotyledons had yellow or brown spots in the center of each cotyledon lobe. Severity of... 

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