Rice

Introduction | Climatic Requirement | Soil Requirement | Cropping System
Field Preparation and Sowing | Nutrient Management | Water and Irrigation | Weed Management
Disease Management | Harvesting | Post Harvesting | Miscellaneous | Location Specific Variety
 

Field Preparation and Sowing:

In Sikkim, rice is being cultivated by (i) direct sowing method and (ii) transplanting method. The later is very popular or widely practised.

Transplanted Rice:
In this method nursery is prepared before the onset of monsoon (May). The main field is prepared with the onset of monsoon because the rainfall occurs during May-June facilitate ploughing the field. The seedlings raised in the nursery are uprooted between 20-35 days after sowing and transplanted in the puddled field followed by usual intercultural operations.

Time of Nursery sowing:
Timely sowing is the best non-monetary input. If sowing is delayed by one week after July the flowering phase and maturity phase are delayed or extended for one more months. The ideal time for nursery raising are:

High hills : 1st week of May to 1st week of June.
Mid hills : 2nd week of May to 2nd week of June.
Low hills : June to early August.

Seed rate:
Seed rate depends upon method of sowing, test weight i.e. weight of 1000 healthy seeds, germination percentage, spacing, number of seedlings per hill and type of rice variety used as follows:

Seed rate for transplanted rice:

Rice types Seed rate (kg/ha) Seed rate (kg/200m2)
Coarse variety 50-55 0.80
Fine variety 40-50 0.50-0.60
Hybrid variety 15-20 0.30-0.40

The optimum seed rate can also be calculated by the user using following rules:

Thumb Rule:

According to this rule seed rate may be calculated as:

Seed rate of paddy = Test weight of paddy (weight of 1000 healthy seeds) x 1.5 kg/hectare.

Formula:
Test weight x No. of seedling/hill
Seed Rate (kg/ha) = ----------------------------------------------- x  100
Spacing in sq. meter for transplanting
 
= A kg

Seed Rate after correction for germination = A x 100/Germination %

Now add 20% more against risk.

Example:
Rice variety Sugandha-II is to be transplanted at a spacing of 20 x 15 cm, using 3 seedlings per hill. The seed has a germination of 90%. Sugandha-II has a test weight of 20 gm. Find out the seed rate for nursery.

Solution:
Test weight = 20 gm
No. of seedling/hill = 3
Germination = 90%
Add 20% against risk = 1/5 kg

20 x 3 x 100
Seed Rate (kg/ha) = ----------------  Kg
 20 x 15
 
= 20 Kg

Seed rate after correction for germination = (20 x 100)/90
                                                                   = 22.2 kg

Seed rate after allowance for risk = 22.2 x (1/5)
                                                     = 26.6 kg/ha.

Selection of Seeds:
Only well filled, viable and certified seeds should be used for rising of nursery so as to transplant these seedlings in the main field after attaining the optimum stage. Heavier seeds having a specific gravity of 1.13 are selected by discarding floating seeds in 27% solution of common salt. This strength of solution can be achieved by dissolving 1kg common salt in 10 liters of water. In such solution, good quality egg floats. Soak the paddy seed in 1.13% salt solution. Remove the ill filled, shriveled seeds floating on the surface of water. Stir the seeds by hand and wait for 1 minute. Remove the floating seeds again. Repeat the process for once again after ½ an hour. The selected seeds are immediately washed and use for rising seedlings.

Preparation of seeds for Raising Nursery:
1. Soak the seeds in water for overnight.
2. In the next day morning, decant the water as well as floating seeds and transfer the soaked seeds into jute bag (gunny bag).
3. Close the bag and lay down on ground horizontally.
4. Cover the gunny bag containing seeds with empty gunny bags to avoid direct contact with sun light. (Do not stack the seed bag one over another).
5. Sprinkle water on seed bag morning and evening to maintain adequate moisture for germination.
6. Seed start sprouting from 24 hours and continue up to 36 hours (two days and one night). Examine the sprouted seed by opening the bag.
7. If sprouting is satisfactory (i.e. 36 hours after incubation) the seed can be taken to the field and broadcasted in nursery. 8. Do not incubate the seeds beyond 36 hours as it leads to excess growth of radicle/plumule which gets damaged while broadcasting.

Seed treatment:
Seeds and seedlings of paddy can be treated before sowing or at the time of transplanting to enhance the productivity and reduce the disease incidence.

Organic treatment:
For the control of damping off and fungal diseases, seed can be treated with fungal culture, Trichoderma harzianum, Trichoderma viride and Trichoderma vivens 10 g per kg of seed. Seed can also be treated with Pseudomonas bacterium culture @ 10g per kg of seed to minimize the incidence of blast and bacterial blight.

Bio-fertilizer treatment:
For efficient use of soil nutrients like Phosphorus, seed is to be treated with Phosphorus solublizing bacteria (PSB) and for N, the N-fixing cultures i.e., Azolla, Azospirillum, Azotobacter and Cynobacteria are to be used.

Methods of nursery preparation:
Soon after enough rain, field should be ploughed followed by harrowing and then planking. All the uprooted and the established weeds along with the stubbles of previous crop should be picked up, collected and thrown out of the field. Summer ploughing has proved beneficial in increasing water infiltration rate and reduces weeds. There are three methods of nursery raising viz.

Dry bed method:
Field is prepared in the dry condition by ploughing 3-4 times or till soil becomes well pulverized and leveled. Divide the required area into small beds of 1.25-1.5m width and of convenient length (8.0 x 1.25m=10m2) providing 40 cm channels in between beds. On an average 50-60 such beds are needed to supply seedlings for planting 1 hectare area. Raise the beds 10-15 cm high and give a gentle slope for draining out the excess water. Sow the dry seeds in 10 cm rows at 3-4 cm deep into the soil. Add FYM (10-15 t/ha) before on set of Monsoon. Adjust the fertilizer requirement according to soil test value or organic manure applied into the soil.

Dry bed nursery of rice


Wet bed method:
This method is suitable in humid tropics and sub-tropics and in irrigated rice lands. The area and fertilizers requirements are same as that of dry bed method. After summer ploughing fields are flooded with water before sowing. The flooded fields are than tilled by 3-4 runs with desi plough. Light paddling is desirable for the nursery raising. Divide the field in small strips (beds) of 1.25-1.5m width with convenient length. The total area of nursery should be 800 m2 or 1/10 of a hectare for 1 hectare planting. Raise the beds up to 15 cm and provide the space (channels) of 40-50 cm all around for draining out excess water and irrigation. Level the nursery beds after mixing the fertilizers. Broadcast pre germinated seeds uniformly on to moist field. Keep nursery beds moist initially and than raise the water depth up to 4-5 cm as the seedlings grow. Drained out the water if stagnates during hot summer days. For controlling Zinc-deficiency (Khaira disease), 2 foliar spray of ZnSO4 is to be done @ 0.5 % ZnSO4 + 0.25 % Slaked lime solution. If crop shows nitrogen hunger (yellowing), then add urea @ 2 % instead of slaked lime. First spray is to be done at 12-15 days after sowing and second at 20 days. Apply ZnSO4 @ 25 kg per ha at the time of transplanting in the main field or 2 kg ZnSO4 in the nursery.


Dapog or mat nursery
Dapog or Mat Nursery:

For machine transplanting mat type of paddy nursery is essentially required. This is a quick method and similar to Dapog type. The nursery is raised either on Pakka floor or in the field. It requires very less area of about 60 m2. But Seed requirement is high (60 kg/ha). In this method the nursery area is divided in small strips having 1.0 -1.6 m width giving 40-60 cm space in between for movement. The nursery beds are raised up to 20 cm and spread banana leaves or polythene sheet over it. Put banana briquette or Bricks all around for the support. Spread a thin layer of Soil +FYM (2:1) mixture uniformly. Then, pre-sprouted seeds are to be spread over it @ 1 kg per m2 area or 50 times of test weight per square meter and press lightly. Sprinkle the water gently. Again spreads a thin layer of FYM enriched soil mixture and then give water in the same manner. There is no need of fertilizers to be applied in the nursery. Nursery will be ready within 10 to 15 days. Before transplanting pile the nursery upward. Keep moist. If the seedlings are used in conventional transplanting method then remove it carefully and transplant 3-4 seedlings at one place. If transplanting is done by transplanter then whole mat is to be divided into a number of specified size which can be fixed over the trays of Transplanter.

Field Preparation and Sowing:
In the hilly terrain of Sikkim, farmers have built leveled terrace depending upon the slope to ensure prevent soil erosion. Number of ploughing and harrowing are depends upon soil type and implements used. Generally1-2 ploughing are done during summer month (May-June) followed by one ploughing before the field preparation. Heavy soil requires more tillage than light textured soils. One cross harrowing instead of ploughing is more useful to crush the crop residues and weeds. Harrowing destructs the big clods into smaller one and upon flooding it churns the soil and makes soil muddy. Spread the recommended dose of Farm Yard Manure or compost and incorporate well in the top surface of soil.

Leveling:
Proper leveling should be done for the paddy field, so that good water control could be maintained throughout the crop season. Terrace should be leveled with Dandy (Leveling Beam) and then with Phyauri (Wooden Hand Leveler).

Puddling of rice field:
Fresh terrace bund should be made with kudali and old bunds should be repaired by trimming and plastering. If necessary flood the field with 5 to 10 cm water a day before puddling and than plough the field twice or thrice. Puddling is to be done with country plough. Depending upon soil condition and weed growth two to three ploughing is required to make the field ready for transplanting. Clods can be broken manually using spade or using harrow or Burmesetum. Before transplanting level the field using wooden plank.

Puddling is a process in which water is led into field and ploughed under standing water. Weeds and crop residues incorporated into the soil. It provides ease of transplanting as soil becomes muddy. Puddling retains the water for longer time and thus, reduces percolatory losses of water. It destructs the native soil structure by repeated ploughing which is desirable for paddy crop. Puddling also helps in the accumulation of ammonia, P, Si, Fe and Mn.

Lifting of Seedlings:
After attaining the optimum stage of seedlings i.e. 4 leaf stage or about 21 to 25 days after sowing in short duration varieties and 30 to 35 days after sowing incase of long duration varieties they are lifted up carefully to minimize root injury and kept in shade to avoid water losses from the plant. If the soil of nursery bed becomes hard then seedlings should be uprooted in the presence of water as it looses the soil particles.

Time of Transplanting:
The optimum time for transplanting of paddy in Sikkim was found from 1st week of June to 15th July as they get maximum rainfall during this period which facilitates the establishment of seedlings. It has been observed that delay in transplanting by 1 day beyond 30 days of nursery the grain yield is reduced 50 to 100 kg/ha however delayed transplanting can be manipulated by bunch planting means more number of seedlings than the recommended level should be planted in a hill, higher dose of nitrogenous fertilizer, selection of varieties having least variation. Increasing plant population by 33% boosts the crop productivity.

Transplanting distance and number of seedlings/hill: Usually 2 to 3 young healthy seedlings of 21 to 25 days old should be planted in a hill at a distance of 20 x 15 cm, row to row and plant to plant respectively as it facilitates the intercultural operations.

Transplanting Method:

Manual Transplanting:
It is more popular in India including Sikkim, and is becoming increasingly expensive besides required plant population and transplanting distance is not maintained. In this method seedlings are planted manually in well puddle and muddy soil having a thin layer of water. Planting should be done in double rows in sunrise and sunset direction which helps in the better transmission of sunlight and better movement of Carbon di oxide in the field.

Mechanical Transplanting: It is more popular in Japan, Korea, China, Philippines and is being tried in India. By this method required number of seedling and transplanting distance can be maintained effectively which is an essential factor for the plant growth and development and over all productivity.

Method of sowing: Seeds can be sown either by broadcasting or line sowing which are discussed below:

Broadcasting method: In this method seeds are broadcasted by hand over the well ploughed land once in east west and again north south direction to cover the area uniformly. Thereafter seeds are incorporated well in the top surface of soil so that they could be fully covered with a thin layer of soil having sufficient moisture for germination. It is one of the most popular methods of sowing but it has some difficulties in the intercultural operation.

Line Sowing method: This method is far superior to the broadcasting method because line sowing of crop facilititates the cultural operations and also enable to identify the weed seedlings even at early stage. In this method seeds are sown in the rows by keeping a proper distance using specific machine called seed drill. For this purpose various type of seed drill have already developed in our country drawn by machine or animal. 

Depth of Sowing:
The seeds of rice should be sown at 5 cm depth. Depth of sowing also varies with the size of seed. A thumb rule regarding depth of sowing is 4 times of the size of seeds.

Introduction | Climatic Requirement | Soil Requirement | Cropping System
Field Preparation and Sowing | Nutrient Management | Water and Irrigation | Weed Management
Disease Management | Harvesting | Post Harvesting | Miscellaneous | Location Specific Variety