Rice is a cereal grain and one of the most important staple foods in the world. It is the seed of the grass species Oryza sativa (Asian rice) or Oryza glaberrima (African rice). Rice is a primary food source for a significant portion of the world’s population, particularly in Asia.
Rice is the second major cereal crop after wheat in Pakistan and the second largest earner of foreign exchange after cotton. It was grown on 3537 thousand hectares last year with the production of 9323 thousand metric tones. The area used for rice production has been expanding over the last several years.
Global Rice area:
- Asia: Asia is the largest producer and consumer of rice. Major rice-growing countries in Asia include China, India, Indonesia, Bangladesh, Vietnam, Thailand, and Myanmar. Together, these countries account for a significant portion of the global rice area.
- Africa: Rice is also grown extensively in various countries in Africa, including Nigeria, Egypt, Madagascar, and Tanzania.
- Americas: In the Americas, countries like Brazil, the United States, Colombia, and Argentina cultivate rice.
- Europe: Rice cultivation in Europe is concentrated in countries such as Italy, Spain, Greece, and Portugal
Botany of Rice
- Kingdom: Plantae (Plants)
- Division: Magnoliophyta (Flowering plants)
- Class: Liliopsida (Monocotyledons)
- Order: Poales
- Family: Poaceae (Grass family)
- Genus: Oryza
- Species: Oryza sativa (Asian rice) or Oryza glaberrima (African rice)
- Inflorescence of Rice is Panicle
Rice root system
Rice plants have a fibrous root system, also known as adventitious roots. Here are some key characteristics of the fibrous root system in rice:
- Origin: The fibrous roots in rice plants develop from the base of the stem, known as the crown. These roots emerge from the lower nodes of the stem and spread extensively in the soil.
- Structure: The fibrous roots of rice are fine, thread-like structures that branch extensively, forming a dense network in the soil. Unlike taproots found in some plants, rice does not have a single dominant root but rather a cluster of small, similar-sized roots.
- Function: The fibrous root system in rice plays several important functions. It anchors the plant in the soil, providing stability and support. The roots absorb water and nutrients from the soil, facilitating the plant’s growth and development. The extensive branching of fibrous roots enables efficient nutrient and water uptake.
- Adaptation to Waterlogged Conditions: Rice is often cultivated in paddy fields, which are flooded or have saturated soil conditions. The fibrous root system of rice is well-adapted to these waterlogged conditions. It helps in oxygen uptake from the soil and provides stability to the plants in the flooded environment.
- Soil Interaction: The fibrous roots of rice interact with the soil, promoting soil aeration and enhancing soil structure. The roots help in the formation of soil aggregates, which improve soil porosity and water infiltration.
The fibrous root system of rice is an important adaptation that enables the plant to efficiently absorb water and nutrients from the soil, withstand flooding, and maintain stability in paddy fields.
Characteristics of Rice
- Monocot: Rice belongs to the monocot group, which means it is a flowering plant that has a single cotyledon (seed leaf) in its embryo. Other examples of monocots include grasses, lilies, and orchids.
- C3 Pathway: Rice follows the C3 photosynthetic pathway. This pathway is the most common type of photosynthesis in plants, where the initial carbon fixation step produces a three-carbon compound. Rice plants use this pathway to convert carbon dioxide into organic compounds during photosynthesis.
- Short-day Plant: Rice is classified as a short-day plant or a long-night plant. It requires a shorter duration of daylight (usually less than 12 hours) to initiate flowering. This means that rice plants typically flower when exposed to shorter daylight periods during specific seasons.
- Self-pollination: Rice is primarily a self-pollinating plant, where the pollen from the stamen (male reproductive structure) is transferred to the stigma (female reproductive structure) of the same flower or within the same plant. However, cross-pollination can also occur to a certain extent through natural mechanisms like wind or insects.
- Plant Population: The recommended plant population for rice is mentioned as 160,000 plants per acre. This indicates the ideal number of rice plants to be grown in an acre of land for optimal yield and spacing. The specific plant population can vary depending on factors like variety, soil fertility, and cultivation practices.
Types of Rice
A. Asian Rice – Oryza Sativa
Asian rice, scientifically known as Oryza sativa, is one of the most widely cultivated and consumed types of rice in the world. It is native to Asia and has been cultivated for thousands of years. Here are some key features and varieties of Asian rice:
- Indica Rice: Indica rice is a major subgroup of Asian rice. It is characterized by long and slender grains with high amylose content. Indica rice varieties are grown in various countries, including India, Bangladesh, Thailand, and Vietnam. Basmati and Jasmine’s rice are popular examples of Indica rice.
- Japonica Rice: Japonica rice is another subgroup of Asian rice. It has shorter and rounder grains compared to Indica rice. Japonica rice varieties are commonly grown in East Asian countries such as Japan, Korea, and China. Sushi rice and Calrose rice are examples of Japonica rice.
- Sticky Rice: Sticky rice, also known as glutinous rice or sweet rice, is a type of Asian rice that has a high amylopectin content, which gives it a sticky texture when cooked. It is widely used in various Asian cuisines, particularly in dishes such as sticky rice balls, rice cakes, and desserts.
- Fragrant Rice: Fragrant rice varieties are highly aromatic types of Asian rice. They are known for their distinct fragrance and flavour. Basmati rice from the Indian subcontinent and Jasmine rice from Thailand are popular examples of fragrant rice.
- Hybrid Varieties: In addition to traditional varieties, Asian rice also includes hybrid varieties that have been developed through breeding programs. These hybrids often exhibit improved yield potential, disease resistance, and other desirable traits.
Asian rice plays a vital role in the diets and cultures of many Asian countries. It is a staple food for a large portion of the world’s population and is consumed in various forms such as steamed rice, rice noodles, rice porridge, and rice flour-based products.
B. African Rice – Oryza Gglaberrima
African rice (Oryza glaberrima) is a species of rice that is native to West Africa. It is an important staple food in several countries in the region. Here are some key features of African rice:
- Origin: African rice is believed to have originated and been domesticated in the inland delta regions of West Africa, particularly in present-day countries such as Nigeria, Guinea, and Sierra Leone.
- Grain Characteristics: The grains of African rice are generally shorter and rounder compared to Asian rice varieties. They have a reddish or brownish husk and a broader width.
- Adaptation: African rice is well adapted to the hot and humid environments prevalent in West Africa. It has developed tolerance to certain diseases, pests, and challenging growing conditions in the region.
- Cultural Significance: African rice has significant cultural and historical importance in West African traditions and cuisines. It has been cultivated by local communities for generations and is often used in traditional dishes.
- Genetic Diversity: African rice exhibits higher genetic diversity compared to Asian rice. This diversity has allowed for the identification and utilization of unique traits, such as resistance to specific diseases or adaptation to local growing conditions.
Although Asian rice (Oryza sativa) is more widely cultivated and consumed globally, African rice (Oryza glaberrima) remains an important crop for food security and cultural heritage in West Africa. Efforts are being made to improve its productivity, enhance its nutritional qualities, and conserve its genetic diversity for the benefit of local farmers and communities.
Growth Stages of Rice
Germination/Emergence: This stage begins when the seed absorbs water and starts to swell. The seedling emerges from the soil, and the first leaves, known as the coleoptile and first true leaf, appear.
- Tillering: During the tillering stage, multiple shoots, known as tillers, emerge from the base of the main plant. These tillers contribute to the overall plant population and potential yield.
- Stem Elongation: In this stage, the rice plant undergoes rapid stem elongation, and the height of the plant increases. The leaves continue to develop, and the root system expands.
- Panicle Initiation: Panicle initiation marks the transition from vegetative growth to reproductive growth. The panicle, which contains the rice flowers, starts to develop at the tip of the stem.
- Booting Stage: During the booting stage, the panicle continues to grow and elongate within the boot leaf sheath. The boot leaf sheath protects the developing panicle.
- Flowering Stage: Rice plants enter the flowering stage when the florets within the panicle start to open. This is when pollination and fertilization occur, leading to grain formation.
- Milking Stage: The milking stage is characterized by the appearance of milky fluid within the developing grains. The grains are still soft and contain high moisture content.
- Dough Stage: In the dough stage, the grains undergo further development and begin to harden. They change from a milky texture to a doughy consistency. The moisture content starts to decrease.
- Maturity: At the maturity stage, the rice grains reach their full size, and the moisture content decreases to the desired level for harvest. The plant starts to turn yellow, indicating the completion of the growth cycle.
These growth stages can vary slightly depending on the rice variety, environmental conditions, and cultivation practices. Monitoring and managing these stages are crucial for optimizing yield and ensuring successful rice production.
Production Technology of Rice
Sowing Time
Bold Varieties | Basmati Varieties | |
Nursery Sowing | 20th May – 7 June | 7th – 25th June |
Transplantation | 20th June – 7th July | 7th – 25th July |
Sowing Time of Rice Varieties
Varieties | Nursery Sowing | Transplantation |
Shaheen Basmati | 15th – 20 June | 15th – 30th July |
Kissan Basmati | 15th – 30th June | 10th – 25th July |
Non basmati fine – PK 386 | 7th – 25th June | 7th – 25th July |
Basmati Hybrid KS 111 | 7th – 25th June | 7th – 25th July |
Bold hybrid | 20th May – 15th june | 25-30 days nursery |
Cultivars/Varieties of Rice
BOLD Varieties | Basmati Varieties | Basmati Varieties |
IRRI-6 KS- 282, 133 NIAB IRRI-9 NIAB – 2003 KSK 434 NIAB GSR-6 | PK 2021 Aromatic NIBG Basmati 2020 Super gold Super basmati 2019 Basmati – 515 PK 1121 aromatic NIAB basmati 2016, | Noor basmati Chana basmati Punjab basmati Kissan basmati shaheen basmati Fine rice (Non-basmati) PK 386 Basmati Hybrid KSK 111 H |
Latest Varieties | Banned Vrities |
Kisan basmati Niab IRRI-9 KSK-282 KSK-13 PK- 386 NIAB 2013 Shaheen Basmati NARC-2019 | Kasmira Malta Super fine Supra Supri Banned varieties have poor quality and low rate in the market |
Land Preparation
The crop and weed residues should be chopped and mixed with the soil at the time of the first ploughing. Two ploughings with successive plankings must be done before sowing for seedbed preparation.
Laser land levelling is compulsory before rice sowing for water saving and uniform crop stand.
Sowing Method of Rice Crop
The seed should be sowed in water for 24 hours and separated into 15-20kg heaps and covered with a wet bag. After 36-48 hour seed will be sprouted.
1. Wet Method (Kaddo kaa tareqa)
- IRRI rice seed: 1kg/ marla
- Basmati rice: 500-700 grams/marla
- Sprouted seed should be transplanted in the field
- 1-1.5 inches of water should stand in the field at transplanting time.
- Nursery will be prepared in 25-30 days
Note: Basmati Rice Nursery should not be more than 25 days.
2. Dry Method (Khush Tareeqa)
- IRRI rice seed: 1.5 kg/ marla
- Basmati rice: 750 grams to 1kg/marla
- Nursery will be prepared in 35-40 days
3. Raab Method
This method is used in Dera ghazi khan and Muzaffargarh where the soil is hard
- IRRI rice seed: 2 kg/ marla
- Basmati rice: 1kg/marla
- Nursery will be prepared in 35-40 days
Major seed distributor
- Punjab and Sindh Seed Corporation
- Rice Research Institute (PRI), Kala shah Kaku and PRI, Dokri, Larkana
- Private seed companies
- Farmer can produce their own good-quality seed
Rice Crop Seed Rate
Method | Basmati Varieties (kg/acre) | Basmati Varities (kg/acre) |
Kaddo (Wet Method) | 6-7 | 4.5-5 |
Khushk (Dry Method) | 8-10 | 6-7 |
Raab Method | 12-15 | Basmati Varieties (kg/acre) |
According to Rice Varieties’ seed rate
Varieties | Wet Method | Dry Method | Raab Method |
Shaheen Basmati, Kissan Basmati, Non basmati fine – PK 386, Basmati Hybrid KS 111 | 4.5-5 | 6-7 | 10-12 |
Bold hybrid | 6 | 6-7 | 10-12 |
Soil condition requirements for Rice
- Heavy Clay or clay loam soil is suitable
- pH tolerant crop: 4.5 to 8.5
- It performs well in acidic soil
Irrigations Requirements of Rice Crop
1. Wet Method
- During nursery sowing time standing water, the depth should be 1- 1.5 inches
- After transplanting water should be standing in a field for 20-25 days
- After this field should be in wet condition (Apply water accordingly)
2. Dry Method
- First water should be applied after 5-7 days of sowing
- After germination apply water to wet the field
- Stop applying water 15-18 days before harvesting
Rice Fertilizer Requirements
1. Wet Sowing
- Basmati Type: 69:41:32 NPK
- IRRI Type 55-36-25 NPK
All Phosphorus (P) and potash (K) & 1/3 nitrogen (N) should be applied at the time of land preparation.
The remaining Nitrogen should be applied in two splits:
- After 30 days of transplanting
- Before flowering
2. Dry Sowing
- A full dose of P & K (1-1.5 bags Dap and 1 Bag SOP per acre) may apply at sowing
- While 80% of the recommended dose of nitrogen (2-2.5 Bags Urea for Basmati and 2.5-3 Bags for non-basmati) should be applied between 30-70 days after sowing
- The remaining 205 nitrogen may be applied before flowering
Apply Zinc Sulphate (33%) @ 6 kg/acre after two weeks of transplanting
Note: The fertilizer doses can be adjusted according to the level of soil fertility
Major Weeds in Rice Crop
- Swanki (Echinochloa colona): Swanki, also known as jungle rice or barnyard grass, is one of the most problematic weeds in rice fields. It competes with rice plants for nutrients, light, and space, leading to reduced crop yields.
- Dhidden (Echinochloa crus-galli): Dhidden, also known as cockspur or barnyard grass, is another aggressive weed that competes with rice plants for resources. It has long, sharp spiky seed heads and can quickly multiply in rice fields.
- Narru (Paspalum distichum): Narru is a grassy weed that commonly infests rice fields. It forms dense patches and competes with rice plants for resources. Its aggressive growth can significantly impact rice yield.
- Madhana (Dactyloctenium Egyptian): Madhana, also known as crowfoot grass, is a perennial weed that can become a problem in rice fields. It spreads through underground rhizomes and can be challenging to control.
- Khabal (Cynodon dactylon): Khabal, also known as Bermuda grass or doob grass, is a creeping perennial weed that can invade rice fields. It forms dense mats and competes with rice plants for nutrients and water.
- Ghora grass (Leptochloa chinensis): Ghora grass is an annual weed that commonly infests rice fields, especially in lowland areas. It has thin, wiry stems and can reduce rice yield if not managed effectively.
Control
- Weeds are a major concern for high productivity in this new rice cultivation system
- The Pre sowing herbicide like “Pendimethalin” & “Stamp” can be applied immediately after seeding
- Then, 30-35 days after sowing, when maximum weeds appear, post-emergence herbicides “Clover” (Bispyrbac Sodium) and “Pyranex Gold 30% WDG can be used for effective control of weeds.
Major Insects of Rice
- Stem Borers: Stem borers, including the Yellow Stem Borer (Scirpophaga incertulas) and the Rice Stem Borer (Chilo suppressalis), are one of the most destructive pests of rice. The larvae bore into the rice stems, causing damage and weakening the plants. Severe infestations can lead to plant lodging and reduced yields.
- Leaf Folder: The Rice Leaf Folder (Cnaphalocrocis medinalis) is a common insect pest in rice fields. The larvae fold and feed on rice leaves, leading to characteristic “V”-shaped leaf folding. Heavy infestations can cause significant defoliation and affect the photosynthetic capacity of the plants.
- White-backed Planthopper: The White-backed Planthopper (Sogatella furcifera) is a sap-sucking insect that feeds on rice plants. It can transmit viruses and cause hopper burn, a condition characterized by yellowing and drying of rice leaves. Severe infestations can result in yield losses.
- Grasshopper: Grasshoppers, including the Rice Grasshopper (Hieroglyphus banian) and the Migratory Locust (Locusta migratoria), can feed on rice plants, particularly during the early stages of growth. They consume leaves and stems, leading to reduced plant vigour and yield.
- Armyworms: Armyworms, such as the Rice Armyworm (Mythimna separate) and the Whorl Maggot (Hydrellia philippina), can cause damage to rice crops. The larvae feed on leaves and can result in defoliation and reduced yield if not controlled.
Insect/Pest Control:
Pest can be managed by local integration of various tactics like
- Use of Resistant varieties
- Modification of pest environment (Removal of alternate food sources, timely sowing, water management (AWD)& manipulation of biodiversity in agri- matrix)
- Conservation and utilization of biocontrol agents (Parasitoids, Predators etc)
- Balanced use of fertilizers and when necessary, an appropriate and timely use of insecticide
Disease of Rice & Control
- Bacterial Leaf Blight
Bacterial leaf blight (BLB), is a major bacterial disease of rice caused by the bacteria Xanthomonas oryzae (Xoo). Infected leaves turn greyish-green and roll up. As the disease progresses, the leaves turn yellow to straw-coloured and wilt, leading whole seedlings to dry up and die
- Blast and Brown leaf spot
Rice blast caused by the fungus Magnaporthe oryzae, is generally considered the most important disease of rice worldwide. Blast symptoms appear on leaves as elliptical spots with light-coloured centres and reddish edges. The most serious damage from a rice blast occurs when the disease attacks the nodes just below the head, often causing the stem to break.
- Stem rot
It is caused by the fungus Magnaporthe salvinii. Stem rot indication would be blackish, dark, irregular lesions visible on the outer leaf sheath. The lesion later expands and affects the inner culm.
- Kernel smut
Kernel smut of rice is caused by the fungus Tilletia horrida synonym Neovossia horrida. Kernel smut of rice reduces grain quality by producing black, sooty masses of powdery spores which replace all or part of the grain.
- False smut
Villosiclava virens (Vv) is an ascomycete fungal pathogen that causes false smut disease in rice. False smut causes chalkiness of grains which leads to a reduction in grain weight. It also reduces seed germination.
Control:
- Seed treatment with available seed dresser like “Topsin M” (70%) WP
- Planting of resistant varieties
- Using fungicide/ bactericides
Copper oxychloride, Cobox etc for BLB
Difenoconazole for Blast
- Balanced fertilizer application & Crop rotation
- Field sanitation and proper water management.
Harvesting
- Appropriate harvesting time ranges from 30-35 Days after flowering. This is the stage when 85-95% of the upper portion of the panicle is straw-coloured
- The harvested crop is left for 2-3 days in the field for drying
- Nowadays, most paddy will harvest with combines in Punjab, which causes a lot of damage to grains and reduces milling recovery
- Grain must be containing 20-22% moisture at the time of paddy crop harvesting
Major recommendation
- Rice straw must be destroyed by 28 Feb
- Rice nurseries do not sow before 20 May
- Maintain 160000 plants per acre :
- P-P& R-R distance is 9 inches and 2 plants per hole.
- In zinc deficiency condition: use zinc sulphate after 10 days of nursery sowing
- In boron deficiency: use 3kg boric acid/4.5 kg (10.5%) Borex per acre at soil preparation.
- Storage moisture should not be more than 12-13%