* Structure of maize grain (Monocot, endospermic Grain )๐๐ป
* Structure of maize grain (Monocot, endospermic Grain "๐๐ป
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It is one seeded fruit called caryopsis or grain because pericarp (fruit wall) is fused with testa . Each grain is made up of following parts :
1. Seed coat. It is the outer brownish layer of the grain. In this, seed and fruit wall are fused together.
2. Endosperm. It comprises the major part of grain and is filled with reserve food. It is composed of two regions (a) Outer single layered aleurone layer, mainly made up of aleurone proteins (b) Inner starchy endosperm. It is separated from embryo by a layer called epithelium.
3. Embryo. It contains a single lateral cotyledon called scutellum and embryo axis with plumule and radicle are at its two ends. Root cap protects the tip of radicle. Radicle is surrounded by a protective sheath called coleorhiza. Plumule is also protected by a covered sheath known as coleoptile.
Show of image in (Maize Grian):๐๐ป
* Seeds as physiological enigma :๐๐ป
Seeds have been considered as physiological enigma of living world. They contain a miniature plant, a protective seed coat, reserve food for future growth and little long lived RNA to guide future metabolism and growth.
It is interesting to note that living cell dies if water contents fall below 45-75% but seeds continue to live with 10-15% water content. In seeds, metabolism is suspended animation like in hibernating animals. In seed, all of a sudden growing embryo becomes dormant and stops growth. Food becomes immobile and respiration becomes anaerobic in mature seed. Seeds are able to tolerate high and low temperatures. However at the time of germination seeds destroy chemical inhibitors and start secreting growth hormones.
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