Organic amendments

The endosperm or endosperm is the tissue nutritional formed in the embryo sac of seed plants , is triploid (three sets of chromosomes ) and can be used as a source of nutrients for the embryo during germination. It is composed of cells tightly packed and starch granules embedded in a matrix, much of it is protein .
The endosperm is a storehouse of food for the embryo of the seeds of various plants angiosperms .

Depending on how cell division occurs after the formation of endospermogen?tica cell (the cell produced by the fusion of two polar nuclei of the embryo sac with one of the generative nuclei of pollen grain ), one can distinguish three types of development endosperm:
Cellular endosperm is the type of endosperm development in the nuclear divisions are accompanied by the development of cell walls isolated uninucleate or multinucleated cells.

In other words, in this kind of development divisions of the cell nucleus are accompanied by the formation of a cell wall that divides the two resulting nuclei.
Nuclear endosperm : in this type of endosperm development of the first divisions of the cell nucleus endospermogen?tica are not accompanied by the dvisi?n the cytoplasm via cell walls, so forming cells with many nuclei. These multinucleated cells, or cenocitos , may later form cell walls.
Endosperm helobial : This type of endosperm development is intermediate between the above two types. After the first division of the cell nucleus endospermogen?tica, forming a cell wall that separates the daughter nuclei. However, subsequent nuclear divisions in these two cells are not accompanied by cytokinesis, so that both are developed cenocitos. Generally, cenocito formation occurs only in the cell nearest the micropyle .

For over a century, two hypotheses have competed to explain the origin of the endosperm of angiosperms. One holds that it is homologous to a supernumerary embryo whose normal place was modified to "selflessly" to a nutritional tissue. January 81: 1468-1486. The other argues that the fusion of male and female nuclei associated with the initiation of endosperm in angiosperms is not sexual but represents a kind of vegetative stage in the development of female gametophyte. 2 In this sense, the endosperm of angiosperms would homologue of the female gametophyte of gymnosperms. The first hypothesis is supported arguments on the fact that double fertilization in gymnosperms produce embryos and in some models on the effectiveness of the strategy adaptive altruistic. 3 But the second hypothesis, that the endosperm can be homologous female gametophyte gymnosperms, is also consistent from the perspective of genetics of embryonic development of both groups. 4 5 Some recent findings continue to support either theory. The ontogeny of the endosperm in Zea save big similarities in its early stages of an embryo. 6 In contrast, the fact that some mutants in Arabidopsis endosperm without fertilization occur, of maternal origin supports the hypothesis of homology between the endosperm and an ancestral gametophyte.

The amendment is the contribution of a product fertilizer or materials to improve the quality of the soils (in terms of structure and composition , adjusting its nutrients, its pH

Those that are made ??with organic materials such as mulch, soil or brown heather, manure, etc.. Often made ??to improve the physical characteristics of providing soil organic matter .
Improve soil compaction and also provide nutrients .

Amendments may be basic, which affect the physical and chemical properties of the soil (eg, about pH ) establishing a more suitable for the development of a culture or may be organic amendments, which also act on the soil microbial life . Amendments also often contain significant quantities of nutrients and are sometimes synonymous with fertilizers .
Acid soils are neutralized with treatments alkaline . You can use multiple products. The lime is one of the most effective materials.
In alkaline soils, can be used acidifying fertilizers such as ammonium sulfate , the ammonium nitrate or urea . Among the amendments: gypsum is useful for saline and sodic soils and can also provide sulfur .
These elements can be fertilizers , but this is not the main purpose of its use.

In Botany the internode is the portion of stem between two nodes .
The first internode of the plant is the hypocotyl , located between the neck of the plant and the cotyledons . Over cotyledons, is the second internode, called epicotyl . In the epicotyl born the first true leaves of the plant which are in the second internode and all others have an axillary bud. The organization of the cauline system of angiosperms is modular, ie, is an aggregation of repeated structural units or modules. The structural unit normal, typical module consists of an internode, the leaf and bud axillary.
Progressive lengthening of the stem are responsible meristems intercalated pimarios, located precisely in the internodes. When none exist, the stem can not progress and then presents an arrangement of leaves in basal rosette.

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