SEED PRODUCTION OF RICE

ABSTRACT

Rice is a major cereals crop cultivated in all over the world. Rice contain decent amounts of fibre, protein, Vitamin B, iron and manganese. This means it can play a vital role against malnutrition. Rice is cooked by boiling or it can be ground into flour. It is main dishes in Asian, Middle Eastern and many other cuisines. This short article analyses the previous research and studies about seed production of rice. Long time research work which is conducted in several locations has shown different problems in seed production. So, this article highlights seed production of rice and provides necessary adoption for enhancing productivity of seed of rice.

1.INTRODUCTION

It is most important cereal crop in Nepal. It grows from 60 to 3050 m altitude. Of the total cultivated land, rice covers 46% of the total cereal crop cultivation area. Its contribution in national GDP is 25%. Total 79% area of rice is grown in rainfed condition, of which 70% is in low land and 9% in upland. According to season of cultivation, rice can be grouped in 4 types, eg. Spring season rice, summer season rice (upland rice), main (rainy) season rice and Boro rice (winter season rice). The area, production and productivity of rice was 1491744 ha, 5610011 tons and 3.76 t/ha during 2075/076. It is estimated that 96% area cultivated under rice is occupied by improved varieties. Atotal 75 varieties of rice have been released by variety releasing sub committee in Nepal upto 2020.

2. Field standard

2.1. Isolation requirement

Rice is self-pollinated crop but sometimes cross-pollination is also reported, however the extent of cross-pollination ranges between 0.1-4.0%. The isolation distance for foundation and certified seed should be fixed by minimum distance of 3 mt from plots of other varieties of rice.

2.2. Varietal purity

The maximum permissible limit of off type plants in foundation seed plots is 0.05% and in certified seed plots of 0.2% at final inspection. The objectionable weed plants (wild rice) should not exceed 0.05% in foundation seed plots and 0.1% in certified seed plots at maturity of seed.

2.3. Seed borne disease

The foundation seed plots should not have more than 0.2% plants affected by neck blast and in certified seed plots should not exceed 0.5% at any inspection between ear emergence and harvesting.

2.4. Roguing

Roguing in necessary to maintain varietal purity standards. During pre flowering stage, rouging should be done on the basis of early or late maturing varieties. All off type and objectionable weed plants should be removed before final inspection, which is normally conducted at full maturity and prior to harvesting of seed crop.

3. Cultural Practices

The crop can be grown by direct seeding or by transplanting methods. For seed production, it is desirable to grow puddle and transplanting system as described below.

3.1. Land selection for nursery

The land should not have been used in the previous year as nursery or general crop of the other varieties to avoid varietal admixture due to the growth of volunteer plants.

3.2. Time of sowing

Third week of May to 1st week of June for long duration varieties and 2nd week of June to 4th week of June for short duration varieties. In case of early rice, third week of Feb. to 2nd week of March is the time of nursery raising.

3.3. Preparation of nursery bed

The soil of the bed should be pulverized by repeated ploughings. Raised bed of 6m x 1.5m x 0.15 m and 50 cm gap between plot should be maintained. That gap or channel between plot may helps to drain the excess water. The total of 50-60 such beds are sufficient to transplant one ha of land.

3.4. Manuring of nursery beds

Apply well-decomposed manure or compost plus 450 gm of super phosphate for 9-m 2 area at the time of final bed preparation and mix them thoroughly with the soil. In area where Khaira disease is prevalent, spray ZnSO4 @ 5 kg plus lime 2.5 kg dissolved in 1000 lit of water /ha of nursery areas at 10 days after seeding and second at 20 days after seeding.

3.5. Seed rate and seed treatment

Seed is to be sown 500-600 gm/bed (9m2 ) i.e. 30-35 kg/ha for coarse and 25-30kg/ha (400-500 gm/bed) for fine rice varieties. Seed should be treated with Agrosan G.N. @ 2.5g/kg of seed.

3.6. Method of sowing

Dry or pre sprouted seed can be broadcasted at the time of seeding. For sprouting, the seeds are allowed to sprout by loosely packing in gunny bag and soaking them in water for 16-20 hours and then drying out excess water completely. The seed bags are kept in damp by covering with wet gunnies till sowing to maintain optimum condition for germination.

3.7. After care

Nursery should be protected for 3-4 days from bird’s damage. Bed should be wet and if excess water is accumulated from any source, it should be drained out and should be kept free of weeds also.

3.8. Transplanting

After 3-4 weeks of sowing, the seedlings are ready for transplanting. Seedlings should be uprooted gently. Weak, diseased or variant seedlings should be discarded.

3.9. Land preparation for transplanting

Land is ploughed 3-4 times to obtain fine tilth and a soft soil. It also creates impervious sub soil condition, due to which the seedlings can establish quickly and plant nutrients are not washed down. If possible, the field should be flooded for 7-10 days before transplanting.

3.10. Fertilizer application

Fertilizer should be applied according to soil test result. In general 100-120 kg N, 50-60 kg P2O5 and K2O (each)/ha should be applied just before the final puddling, where N is applied in 3 split doses. Half dose of N as basal, 1/4th at mid tillering and 1/4th at panicle initiation stage. If deficiency of N is observed in the field, 2% urea can be sprayed. In zinc deficient condition apply 15 kg ZnSO4 + 2.5 kg lime in 1000 lit of water/ha.

3.11. Method of transplanting

Transplant 2-3 seedlings per hill in 2-3 cm depth. The seedlings should not be under or over aged. The spacing is followed as under. a) Shy tillering variety – 20cm x 10 cm to 20cm x 15 cm b) More tillering variety- 20 cm x 15 cm to 20 cm x 20 cm.

3.12. Water management

Water at 3-5 cm depth should be maintained throughout the growth phase of the crop. Irrigation should be given whenever necessary.

3.13. Intercultural operation

The plot should be kept free from weeds by weeding 2-3 times before heading. If herbicides are used, following schedule should be followed.

a) Use 2, 4-D or MCPA 1kg a.i. in 150-250 liters of water/ha at 20-25 DAT to kill broadleaved weeds.

b) To control grasses, use butachlor or benthiocarb @ 1.5 kg a.i./ha at 5-7 DAT in 600-700 lits of water/ha.

4. Field inspection

A minimum of 2 inspections should be conducted. The 1st inspection is conducted at flowering to verify source of seed used for seed production and to check isolation requirements. The final inspection is allowed with the request of seed grower, if the number of off types and objectionable weed plants exceed prescribed permissible limit. During final inspection at maturity of seed crop, actual counts are taken from separate places distributed at random in such a way that whole area of the seed plot is covered. Thousand (1000) ear heads should be included in each count and examined carefully for off types and objectionable weed plants. An inspection and a copy of the report should be handed over to the seed grower.

5. Harvesting and threshing

The crop should be harvested just after physiological maturity by hand with sickles. Seeds are threshed, winnowed to remove chaff, dust, and empty husks and light grains. The clean seeds are dried around 11-12% moisture content for storage.

6. Seed yield

The expected seed yield is 5-8 tons/ha.

7. Seed storage

The seed should be store after proper drying at dry places. The rice bags should be stacked on a wooden pallet in a dry and cool place. Mark the bags with the name of cultivar and other information to avoid mechanical mixing. Do not store different varieties in the same room without stack identification.

CONCLUSION

To sum up, this article emphasizes on the seed production of rice and signifance of rice. With increasing population, high seed production can minimize the pressure of food security all over the world. Nepal has great potential for the production of seed of rice because of diverse agro-ecological environments. Hence, there is further scope to increase seed production of rice through development and popularization of suitable varieties and technologies, streamlining community based seed production, addressing climate change issues and policy reforms for promotion of seed production of rice.

Writer: Deepika Manandhar (Student, Institute of Agriculture and Animal Science, Paklihawa, Nepal)