RICE

Rice

Botanical name	Oryza sativa
Family	Poaceae/ Gramineae
Chromosome no	2n=24
Fruit type	Caryopsis
Inflorescence	Panicle
Stamens	6
Pollination	Self-pollonation
Germination	Hypogeal

Oryza sativa has 3 varietal types:

1.     Indica: Grown in India ( Tropical rice)

2.     Japonica: Grown in Japan ( Sub tropical rice)

3.     Javanica: Grown in Indonesia ( Wild rice)

Ø Lemma and palea together called as Hull.

Ø Lodging doesn’t occur in Japonica spp of rice.

Ø Stem of rice is called Culm.

Ø Rice is a short day plant.

Climate:

Ø Rice crop favours hot and humid climate.

Soil :

Ø Clay or Clay loamy soils with slightly acidic are suitable for rice cultivation.

Ø pH ranges between 4-6.

Temperature:

Minimum	10-12°c
Optimum	30-32°c
Maximum	36-38°c

Seasons of rice cultivation:

Season	Sowing Time	Harvesting
Aus	April-May	Aug-sept
Aman	June-July	Oct-Nov
Boro	January-Feb	April-May

Spacing:

Short duration	20×10 cm
Medium duration	20×15 cm
Long duration	20×20 cm

Rice plant is transplanted at:

Kharif season	21-25 DAS
Rabi season	30-35 DAS
SRI method	10-12 DAS
Depog method	11-14 DAS
Dry land areas	30-35 DAS

Seed rate:

Broadcasting	100 kg/ha
Drilling	60 kg/ha
Hybrid rice	15 kg/ha
Depog method	1.5-3 kg/ha
SRI method	6-8           kg/ha

Test weight of rice -21g

v Rice contains 6-7% protein

ü White rice 7.9%

ü Brown rice 2-2.5%

ü The main protein present in rice is Oryzenin.

Irrigation:

Ø Generally cereal crops required about 400-500 liters of water.

Ø But rice consumed 10 times more water

Ø 5000liters of water to produce 1kg rice grain.

Ø Rice field submergence in 5cm deep water during the reproductive and grain formation stage.

Ø Water use efficiency  (WUE) 3.7 kg/ha mm

Critical irrigation stages:

ü Tillering

ü Flowering

Manures &Fertilizers:

ü NPK ratio 100:60:60 kg/ha

ü FYM 200-300q/ha.

Oil content in rice bran:

Raw rice bran	12-18%
Parboiled bran	20-28%
De-oiled bran	1-3%

v Hulling percent in rice -66% or 2/3 of paddy

Minimum support price for Rice 2014-15 to 2019-20

Rice quality	2014-15	2015-16	2016-17	2017-18	2018-19	2019-20
Common	1360	1410	1470	1550	1750	1815
Grade ‘A’	1400	1450	1510	1590	1770	1835

Processing of rice

v Parboiling

ü It is a pre milling hydrothermal process in which crystalline form of starch is changed into an amorphous form on account of irreversible swelling and fusion of starch.

ü Nearly 60% of the paddy produced in India at present is parboiled

v Milling

ü It is the process wherein the rice grain is transformed into a suitable form for human consumption, therefore, has to be done with utmost care to prevent breakage of the kernel and improve the recovery.

ü There is a loss of Vitamin B , particularly thymine, the deficiency of which causes the disease called ‘beri-beri’ in those persons who continuously eat polished rice.

v Polishing

ü The process of removal of bran layer and smoothening the surface is called Polishing

Grades of Indian rice

·        Common variety: short bold & long bold rice.

·        Fine variety: medium slender rice.

·        Superfine variety: long slender & short slender rice.

Weed management

Two major weeds in rice

1.Echinochola crusgalli                                                    2.Echinochola colonum

     (Barn yard grass)                                                                                             (Wild rice)

                                                    

ü The weed problem is less in low land transplanted rice compared to upland direct seeded.

Isolation distance, SRR,& SMR of paddy

Crop	Isolation distance(m) (self)	SRR	SMR
Rice	3	17	1:80

Yield

Ø A well managed crop variety yields about = 60-70q/ha.

Ø Short duration variety yields about = 45-55q/ha.

Do you know?

Top 10 rice producing states in India

1.     West Bengal

2.     Uttar Pradesh

3.     Andhra Pradesh

4.     Punjab

5.     Tamil Nadu

6.     Bihar

7.     Chhattisgarh

8.     Odisha

9.     Assam

10. Karnataka .

Insect – pests of rice crop

Common name	Scientific name	Family	Symptom
Yellow stem borer	Tryporyza / Scirpophaga incertulus	Pyralidae (Lepidoptera)	Caterpillar alone is destructive. Before flowering it produces ‘Dead heart’ which is known as drying of the central shoot , and plants that is attacked in early stages produce ears devoid of grains and is known as white ear.
Rice hispa	Diclodispa armigera	Chrysomelidae (coleoptera)	Larvae produces transparent blotches on the surface of leaf. The adult also feed on green matter and produces whitish streaks parallel to mid rib on leaves. Severely infected leaves produces white dried up appearance in the field.
Rice gundhi bug	Leptocorisa acuta	Coreidae (Hemiptera)	Incompletely filled panicles or panicles with empty of grains.
Brown plant hopper	Nilaparvata lugens	Delphacidae (Hemiptera)	Due to severe damage plant produces ‘hopper burn’ symptom. Both Nymph&adult damage the leaves by sucking the cell sap which turns the leaves yellow. It is the transmitter of ‘grassy stunt’ virus.
Rice case worm	Nymphula depunctalis	Pyralidae (Lepidoptera)	Larvae feed by scraping the under surface of the leaf blade leaving the upper epidermis intact. Tubular case is constructed by the larvae.
Green leaf hopper	Nephotettex nigropictus/ virescens	Cicadelidae (hemiptera)	Yellowing of leaves from tip to downwards. It is the vector of Tungro virus
White backed plant hopper	Sogatella furcifera	Delphacidae (Hemiptera)	It causes red rust symptoms
Rice gall midge	Orseolia oryzae	Cecidomyiidae (diptera)	It causes ‘silver shoots & onion leaves’ like symptoms
Rice grass hopper	Hieroglyphus banian	Acrididae (orthoptera)	Damage by nibbling of rice ear head.

Diseases of rice

Bacterial leaf blight (Poor man’s disease)	Xanthomonas oryzae	‘Kresek’ symptoms occurs in young seedlings, plant withers and dries up. Yellow color spots on the seedlings
Blast (Rich man’s disease/Air borne)	Pyricularia oryzae	Brown spindle eye or boat shaped lesion on leaf& leaf sheath
Brown leaf spot	Helminthosporim oryzae	This is responsible for The Great Bengal Famine in 1943. Symptoms occurs on the coleoptile of seedlings and cause blighting.
Tungro disease	Vector – green leaf hopper	Stunted growth of plants and yellowing of leaves from tip and margins
False smut	Claviseps oryzae	Few grains are double in size.
Khaira disease		Due to zinc deficiency. Usually occurs in nursery stage. Rust coloured or brownish red coloration on the surface of the outer leaves.