Cultivation of many crops required for food production, depends on the germination of seeds, although there are exceptions where vegetative propagation is carried out. The seeds of legumes and cereals are themselves some of our most important food sources, but their importance lies within the protein, starch and oil storage reserves which are laid down throughout the development and maturation of the plant. Germination begins with the uptake of water by a seed in a process known as imbibition and usually ends, with the beginning of elongation of the radicle (Bewley & Black, 1994).
Seeds do not germinate until they have absorbed water. Embryos in mature seeds are dehydrated and so for active metabolism a watery environment is required.
When a seed is germinating numerous materials are produced and others degraded as the metabolic machinery has been turned on. So water is an absolute requirement for these metabolic processes. Absorption of water into a dry seed is called imbibition and as a seed absorbs water it swells to many times its original size. Imbibition in cells occurs by adhesion of water into and onto materials in the seed like cellulose, starch and pectin. So water molecules are attracted to these materials by attraction between unlike materials, called adhesion. Moreover, germination and growth needs energy which is obtained by conversion of food molecules present in the endosperm or cotyledon of the seeds to ATP by aerobic respiration and usually therefore, oxygen is also needed for germination (Solomon, Berg & Martin, 2005).
[...] So water molecules are attracted to these materials by attraction between unlike materials, called adhesion. Moreover, germination and growth needs energy which is obtained by conversion of food molecules present in the endosperm or cotyledon of the seeds to ATP by aerobic respiration and usually therefore, oxygen is also needed for germination (Solomon, Berg & Martin, 2005). When a seed is said to express dormancy, it means that even when conditions for germination are favourable, such that imbibition, respiration nucleic acid and protein synthesis and many other metabolic events take place, cell elongation for the appearance of the radicle does not take place for reasons that are still vaguely understood. [...]
[...] Each protein is coded for by a different gene. The main function of phytochrome is to detect day length (Solomon, Berg & Martin, 2005). Seeds are normally known to germinate when they are released from the fruit but some seeds undergo precocious germination which takes place inside the fruit. (483 words) OBJECTIVES This experiment aimed at assessing the possible factors that may affect seed germination. Section A of this experiment examined how light affects seed germination while section B studied the effect of planting depth on seed germination. [...]
[...] But for deep planting there is germination for lettuce seeds and green bean seeds from the 3rd day onwards. Light is able to breach the soil and cause germination of light-sensitive seeds below 2 mm from the surface of the soil, but not much deeper, according to studies by Woolley & Stolle But the results of this experiment show that deep potted seeds germinated while the seeds close to the surface did not germinate. This means that green bean seeds were not light-sensitive but rather required shade from light during growth and hence, required a deeper planting depth. [...]
[...] Then the number of germinated seeds was counted on the 3rd and 8th day. Section Effect of fruits 3 Petri dishes were labelled as ‘Water+Light', ‘Tomato juice+Light' & ‘Abscisic acid+Light'. A filter paper was then placed in each dish and then 5 mL of distilled water, tomato juice and abscisic acid was poured in into the dishes labelled ‘Water+Light', ‘Tomato juice+Light' & ‘Abscisic acid+Light', correspondingly. Then 50 lettuce seeds were placed promptly onto each Petri dish. The dishes were closed with lids and kept under lighted conditions to germinate. [...]
[...] Solomon, E.P., Berg, L.R. & Martin, D.W. (2005), Biology, Thomson- Brooks/Cole Learning, Belmont, USA, pp. 688-691. Woolley, J.T. & Stolle, E.W. (1978), Light Penetration and Light-induced Seed Germination in Soil. Plant Physiology, 597-600. [...]
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