Unit I
Chapter 1 - Rice
Common Name: Paddy in English
Botanical/Scientific Name: Oryza Sativa L.
Chromosome No.: 24
Family: Poaceae
Wild Species: Oryza Sativa fatua
Origin
Oryza sativa is grown in all rice-growing areas and Oryza globerrima is confined to West Africa only. It indicates that there might be two centres of origin of rice, i.e. south-eastern Asia ( India, Myanmar & Thailand) and West Africa.
Geographical Distribution
ᐧ Rice is grown in more than a hundred countries. The total harvested area is approx. 158 million hectares and production are more than 700 million tons annually ( 470 tons of milled rice).
ᐧ 90% of world rice production is grown in Asia (Nearly 640 million tons). Sub-Saharan Africa produces nearly 19 million tons and Latin America some 25 million tons.
ᐧ China and India (112.9 million tons) are the world's largest rice producers. India has the largest area (43.2 million hectares).
ᐧ The next largest producers are Indonesia Bangladesh Vietnam Myanmar and Thailand. These 7 countries together produce 80% of the world's rice.
ᐧ 90% of world rice production is grown in Asia (Nearly 640 million tons). Sub-Saharan Africa produces nearly 19 million tons and Latin America some 25 million tons.
ᐧ China and India (112.9 million tons) are the world's largest rice producers. India has the largest area (43.2 million hectares).
ᐧ The next largest producers are Indonesia Bangladesh Vietnam Myanmar and Thailand. These 7 countries together produce 80% of the world's rice.
Economic Importance
• Can grow in the wet environment while other crops can not grow
• Most important food crop in the world
• India is the second-largest producer of Rice
• Great source of Energy.
• Most important food crop in the world
• India is the second-largest producer of Rice
• Great source of Energy.
Botany
Root System:
When a rice grain germinates in a well-drained, upland soil the sheath (coleorhizae) emerges. The primary embryonic root (radicle) comes out through the coleorhiza shortly after it appears. This is followed by secondary roots, all of which develop the lateral roots.
If it emerges in submerged low lands, coleoptiles emerge ahead of the coleorhizae.
Shoot System
Collectively applies to all parts of the plant above ground level. It is mainly composed of the following parts:
(1) Culm
• It is made of a series of nodes and internodes
• Culms are usually hollow except at node.
• Buds near ground level grow into tillers.
• The primary tillers give rise to secondary tillers which give tertiary tillers.
(2) Leaves
• Sessible in nature. The Leaf blade is attached to the node by leaf sheath.
• Leaf number is more on primary tillers than secondary tillers.
(3) Panicle
• The rice inflorescence known as panicle is a group of spikelets borne on the uppermost node of the culm.
(4) Spikelet
• The individual spikelet consists of two outer glums
• Parts found on outer glums are collectively called a floret.
• It consists of hard covering the two sections of which are known as lemma or palea (the glums)and the complete flower is between them.
• The lemma and palate together are known as 'hull'.
(5) Grains (Caryopsis)
• The grains are tightly closed by lemma and palea sheath.
• The hulled rice grain is known as brownish pericarp covers it. Pericsrp is the outermost layer removed when rice is milled and polished.
Varieties
Jaya is the 1st high yielding variety of rice.
(1) High yielding varieties:
(I) Rainfed -
a) Rainfed upland - Narendradhan 97,18,118,80, Renu Aswani, Saket 14, Tulasi, Aditya, Pusa 1121, Pantdhan16, Ranu, sudha
b) Shallow lowland- Madhukar, Salivahana, Mahsuri, Savitri, Swarnadhan.
(II) Semi-deep or Deep water - Jal lahri, Jalnidhi, Jalpriya.
(III) Irrigated- Ajaya, Vikas, Manhar, Govind, Saket 4.
(2) Other high yielding varieties: IR-8, 20, 36, 64, MTU-1010, Kranti (R-2012), Purnima, Swarna, Pusa Basmati - 1,6, Pusa Sugandha- 2, 3, 5.
(3) Hybrid rice: DRRH-2, APHR-1, Pusa-RH-10, KRH-2
Ecological Requirement
Season: Kharif, rabi, zaid
Climate: Hot and Humid
Soil:
• Can be grown any type of soil.
• Clay and Clay loams soils are best suited because it is capable of holding water for a long duration.
• Grow in submerged conditions.
PH: 5.5- 6.5
Temperature: Optimum Temp.: 20-27 C
For germination: 21-30 C
For translating : 15 C
For growth: 25 C
For tillering: 32-34 c
For Flower initiation: 25-30 C
For anthesis ( opening of flower) : 30C
For ripening: 23-25C
Cultivation: wetland (lowland) and dryland systems.
Selection of varieties: varieties of 100-195 days should be selected.
(1) Dry cultivation:
Field preparation:
• The field should be ploughed with soil turning plough.
• This is helpful in weed eradication as well as improvement in the water holding capacity of the soil.
• This field should be prepared and bunds should be made around the field just after the first shower of monsoon.
Seeds and Sowing:
a) Seed treatment: treat the seed at the rate of 10kg seed with 5g emisan, 1g streptocycline or 2.5g agromycine 100 or pausamycine in 10 litres of water for 24 hrs.
b) Broadcasting: When the field is in the right conditions, broadcast the seeds, mix the seeds with the help local plough or disc harrow. use 100 kg seeds per hectare.
c) Sowing seed behind the plough or drilling: Drill the seed with seed drill or behind the plough with the help of a funnel in rows after applying fertilizer.
Row to row distance- 20cm and 60 kg seed per hectare
(2) Wet cultivation:
In this system, the field is brought to a soil puddle by repeated ploughing with 5-7 cm standing water.
Methods used:
a) Transplanting in the puddled field.
b) Broadcasting sprouted seeds in puddled fields.
Wet bed method: Used where water is abundant. The seedbed is usually prepared 25-30 days before transplanting.
1. Seedbed area is ploughed twice
2. Sow pre-germinated seeds.
3. Keep the bed saturated with water for 1st five days.
4. Appropriate control measures should be taken for pests and diseases in the nursery they occur.
Drybed method: Plough field 3- 4 times till the soil is thoroughly pulverized. Maintain a thin layer of water if possible after 5 days of sowing.
Dabog Method: Introduced from the Philippines. Less area (25-30 sq. meters for one-hectare land) is needed to raise seedlings.
Transplanting
1. The seedlings are uprooted from the nursery at the optimum age (3-4 weeks for short duration & 4-5 weeks for medium and long duration varieties).
2. two-three seedlings per hill at 20 * 10 cm distance.
3. at 2-3 cm depth.
4. 50 hills per sq. meter to assure adequate population in a rice field.
SRI (System of Rice Intensification)
Rice seedlings should be soaked in water. The nursery should be established in organic soil (because C: N ratio is 20:1). One main advantage is that the seeds are attached with seedlings when uprooted for transplanting so there will be a less or low transplanting shock.
- Done in Square Geometry
- 1 seedling per hill
- Area- 97.2 m2 (100 m2) or 1000square foot
- Seed rate = 5-6 kg/ha
- Ideal in the whole world
Nutrient Management in soil
about 10 - 15 tonnes of well rotted FYM or compost per hectare should be applicable at 4-6 weeks before sowing.
The root zone is converted from aerobic to anaerobic environment.
This wet seed treatment gives protection to the seedlings up to 40 days from seedling disease such as blast and this method is better than dry seed treatment.
• For rainfed rice: N= 60-80 kg/ha
P2O5 = 30-40 kg/ha
K2O = 15-20 kg/ha
• For irrigated/transplanted rice-
For HYV:
N= 100-120 kg/ha
P2O5 = 50-60 kg/ha
K2O = 25-30 kg/ha
ZnSO4 = 25 kg/ha
For hybrid:
N= 120-150 kg/ha
P2O5 = 60-75 kg/ha
K2O = 40 kg/ha
ZnSO4 = 25 kg/ha
Time of application: 1/2 N and full dose of P2O5 and K2O at the time of basal application. Remaining 1/2 N into two split doses.
1/4th: at 30 days after transplanting
1/4th: at 55-60 days after transplanting
Method of Application :
1. Hill Placement, 2. Band Placement.
Weed Management
Monocot weeds: Echinochloa colona, Echinocloa crusgalli, Cynodon dactylon, Commelina benghalensis.
Dicot weeds: Eclipta alba, Ageratum conyzoides, Phyllanthus fraternus.
Seddes: Cyperus iria, Cyperus difformis, Fimbristylis miliaceae.
Critical Period:
• For upland rice- 15-45 days.
• For transplanted rice- 30-45 days
Control of Weeds:
- Mechanical weeds- in upland cond., do hand weeding at 20-40 days after sowing.
- Cultural/Agronomical method - Impounding of water in the field for 4-15 days after transplanting up to 5- 7.5 cm depth.
- Chemical method-
- Pre-emergence herbicides :
- Pendimethalin @ 1 kg/ha ( Stomp-30)
- Acetachlor@0.75 kg/ha
- Anilophos @ 0.45 kg/ha (Rice-30)
- Post Emergence herbicides:
- Fenoxaprop=p-ethyl
- Bispyribac-Na @ 20 g/ha ( Nominee gold)
- 2,4 D @ 0.5 kg/ha (Weedone)
- Azimsulfuron @ 25 g/ha (Segment)
- Penoxsulam @ 35 g/ha ( Granite)
Water Management
Nursery- 50-60mm
Main field preparation- 200-250
Planting to panicle initiation (PI)- 400-550mm
PI to flowering- 400-450mm
Flowering to maturity- 100-150
Total- 1200-1460mm
Disease Management
Blast: caused by pyricularia oryzae. Eye shaped spots gray or dark brown margin appear on the leaf and leaf sheath.
Control measures: treat the seeds at the rate of 10 kg /ha with 5g emisan, 1g streptocycline or 2.5g agrimycne 100 in 10 litres of water for 24 hours before sowing.
Brown spot: caused by Cochiobolus miyabeans (Heminthosporium oryzae). Also appear on grains where black spot appear on grains where black spot appear on glums.
Control measure: Add muriate of potash to correct the deficiency in soil, because the severity of disease increase in deficient soils. Apply balanced NPK fertilezers.
Khaira: The disease is caused by zinc deficiency. Usually appear in nursery but may appear , in patches, after 10-15 days of transplanting. Growth of plant is stunted. In severe cases, plant fail to grow further but sometimes there is natural recovery after 6 weeks of age.
Insect Pests
Stem borer: caused by larva of these insects.
Control:
1. Apply 3% carbofuran @ 30-33 kg /ha in 3-4 standing water. Apply at 20-25 days and 50-60 days.
2. Grow resistant varieties
Gall midge: Regular tillers are transformed into tabular galls, resembling the leaf of onion. This is a sucking type of insect.
Control: Same as Stem borer
Rice hispa: Scrap on the upper surface of the leaf blade, leaving only the lower epidermis.
Control: Spray Phosphamidon 85 @ 0.5 mm in 1l of water or Monocrotophos 36 EC @ 1mm in 1 l of water.
Harvesting and yield
1. Average grain yield in rice- 50-60 q/ha
2. Milling in rice- 50-55%
3. Grain: Straw ratio - 1:2
4. Harvesting Index of rice - 40-45% (generally)
5. Oil content in rice bran - 12-18%
6. Oil content in Parboiled Rice contain- 20-28.
