loss of rice due blast disease

Blast Disease of Paddy: Symptoms, Causal Organism and Control Measures


blast of rice

Blast Disease of Paddy
(Symptoms, Casual Organism, Etiology and Control Measures)

loss of rice due blast diseasePaddy/rice

Rice is a cereal grain. It is the seeds of Oryza sativa (Asian rice) or Oryza glaberrima (African rice). Rice is the most extensively consumed staple food of human. It is the major staple food in Asia. Rice is the third highest agricultural commodity in worldwide production. The un-milled rice is known as “paddy“.

Blast Disease of Paddy

Ø  Blast disease is one of the most severe diseases affecting paddy.

Ø  It is a fungal disease prevalent all over the world.

Ø  It is a major problem in rice production in countries like Japan, India, Taiwan and the USA.

Ø  Blast disease is more severe in areas with high humidity and rainfall.

Ø  Losses due to the disease may be up to 90% of the total corp.

Ø  In India, the blast disease is more common in Southern parts, particularly coastal areas.

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vein clearing and vein banding

Mosaic Disease of Tapioca: Symptoms and Control Measures


mosaic disease of tapioca

Mosaic Disease of Cassava or Tapioca
(Cassava Mosaic Disease: Symptoms, Causal Organism, Etiology and Control Measures)

Cassava / Tapioca*

viral mosaic in leavesØ  Cassava or Tapioca (Botanical Name: Manihot esculenta; Family: Euphorbiaceae).

Ø  Cassava is a vegetatively propagated tuber crop plant.

Ø  The root tubers of tapioca are rich in starch.

Ø  Cassava is native to South America. Now the cassava is cultivated worldwide.

Ø  Cassava is a staple food in many regions for about 600 million people worldwide.

Ø  Linamarin is a cyanogenic glucoside found in the roots of cassava plants.

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Botany lecture notes

Pteridospermales (Cycadofilicales)- General Characters, Classification and Affinities


Pteridospermales Characteristis

Pteridospermales (Cycadofilicales)
General Characteristics, Classification and Affinities of Cycadofilicales

What are Pteridospermales?

Ø  Pteridospermales are a group of Fossil Gymnosperms.

Ø  They are also called as Cycadofilicales (Chamberlain used the term).

Ø  As the name suggests, they are the ‘Seed Ferns’.

Ø  They are Gymnosperms with ‘Fern-like’ leaves which produce ‘Seeds’.

Cycadofilicales Seed Fern

The Reconstruction of a Pteridospermales Member. Note the Erect Stem, Fern Like Leaves, Circinate Venation and Vein Pattern

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Botany lecture notes

Similarities and Differences between Pteridophytes and Gymnosperms


Gymnosperm vs Pteridophytes

Pteridophytes vs Gymnosperms
(Similarities and Differences between Pteridophytes and Gymnosperms)

Pteridophytes:

Pteridophytes are a group of primitive land plants belongs to Cryptogams. They are the first plant group with vascular tissue for the conduction of water and food materials and hence they are called as Vascular Cryptogams.

Gymnosperms:

Gymnosperms are a group of primitive seed-producing plants of Spermatophytes (Phanerogams). They are ‘Naked-Seed’ Plants characterized by naked ovules (i.e., ovule without the ovary). The ovules of Gymnosperms are borne directly on the surface of the megasporophyl. Since ovary is absent, Gymnosperms do not produce fruits.

Pteridophytes occupy the intermediate position between Bryophytes and Gymnosperms (seed plants). Gymnosperms were believed to be originated from the Pteridophytes in the Devonian period (419 to 359 million years ago) of Paleozoic Era. Pteridophytes and Gymnosperms share many characteristics. In the previous posts, we discussed the General Characters of Bryophytes Pteridophytes and Gymnosperms. In this post, we will discuss the Similarities and Differences between Pteridophytes and Gymnosperms with Comparison Table.

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Botany lecture notes

Classification of Gymnosperms by Chamberlain (1934)


Classification of Gymnosperms

Classification of Gymnosperms
The Chamberlain System – 1934

Brief history of the classification of Gymnosperms:

There are many systems for the classification of Gymnosperms in the literature. Robert Brown (1827) for the first time recognized Gymnosperms as a separate group of plants. Bentham and Hooker (1883) placed Gymnosperms between Dicots and Monocots in their classification (General Plantarum).

Van Tieghman (1898) gave the status of Major Division to the Gymnosperms. Tieghman also divided the whole Spermatophyta (seed plants) into two divisions namely Gymnosperms (Astigmatae) and Angiosperms (Stigmatae).

Coulter and Chamberlain in 1912 divided the division Gymnosperms directly into seven orders namely (1) Cycadofilicales, (2) Bennettitales, (3) Cycadales, (4) Cordaitales, (5) Ginkoales, (6) Coniferales and (7) Gnetales.

Classification of Gymnosperms by Chamberlain (1934)

Ø  Chamberlain (1934) divided the Gymnosperms into TWO classes and each class into orders.

Ø  Gymnosperms were divided into TWO classes:

(1).      Cycadophyta

(2).      Coniferophyta

Chamberlain System of Classification

Class I : Cycadophyta

Ø  Class Cycadophyta includes both fossil and living forms.

Ø  The stem is unbranched and stumpy.

Ø  Leaves are large and pinnately compound.

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