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  Hybrid Rice

Introduction > Advantages and Dis-advantages > Seed Production > Hybrids Released >


Importance Of Hybrid Rice

Introduction

  • At the current rate of population growth in India, the requirement of rice by the turn of century is estimated to be around 150 million tons.
  • To make the India self sufficient in rice, it is needed to improve the productivity to a greater extent.
  • The task is quite challenging and the options available are very limited.
  • Among the various possible genetic approaches to achieve this target, hybrid rice technology is the most feasible and readily adaptable one.
  • Commercial success of hybrid rice in China has clearly demonstrated the potential of this technology to meet the ever-increasing demands for rice world over.
  • Efforts to develop and use this technology in India, though initiated in 1970s, have been systematized and intensified since December 1989, with launching of a mission oriented project.
  • Within a short span of seven years, half a dozen hybrids each from public and private sectors are made available for commercial cultivation.
  • Some more promising hybrids with better grain quality, resistance to some of the major pests and diseases and higher magnitude of heterosis are in final stages of evaluation.
  • Hybrid seed production technology has been developed and demonstrated on large scale and an average seed yield of 1.0 -1.5 t/ha is being obtained on large scale.
  • During the dry season 1995-96, totally around 1300 tons of F1 seed was produced by private and public sector seed agencies.
  • During the wet season 1996, more than 60,000 hectares were planted to hybrid rice in various parts of India.
Achievements Through Hybrid Rice
  • Hybrid rice has helped china to increase rice production nearly by 200 million tons from 1976-1991.
  • Hybrid rice has yield advantage of more than 30% over conventional varieties.
  • The area under hybrid rice was 17.6 million hectares i.e. 55% of total rice area in china and the production of hybrid rice was 66% of the total rice out put.
  • Although research on the commercial utilization of heterosis in rice has made tremendous gain during the last 20 years, it is from a strategic point of view, that the high yield potential of hybrid rice has not been fully tapped yet.

 
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Ikisan - Advantages And Disavantages Of Hybrid Rice

Advantages AND Dis-advantages

Advantages
  • Average yields of hybrid are more when compared to high yielding varieties.
  • Quantity of seed used in hybrid rice was significantly less than the seed used in conventional high yielding varieties.
  • Average productivity and total return to total input cost was relatively higher for hybrid rice than for conventional high yielding varieties.
  • Hybrid rice cultivation is economically viable if management level is above 60 per cent.
  • The nursery area required for transplanting unit area is less when compared to conventional high yielding varieties.
  • Hybrids are short duration with resistance to major pests and diseases.
  • Hybrids are non-lodging varieties.
Disadvantages
  • Management responsiveness was nearly 30 35 % more for hybrid rice than for conventional high yielding varieties.
  • At an average management level, the grain yield of hybrid (0.8 t/ha) was lower than the minimum required (1.4 t/ha).
  • Seed cost was almost 2.5 times more for hybrids than for conventional high yielding varieties.
  • The expected output price was lower for hybrid rice grain than actual price for conventional high yielding varieties.
  • The hybrid rice seed production usually requires more labour specially to accomplish certain critical farm operations like row planting, supplementary pollination, leaf clipping, gap filling, rouging and GA3 application etc. Hence the cost incurred on seed production was found to be high.
  • Hybrids require more dose of fertilizers.
  • Hybrid seed is not suitable for second crop.

 
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Ikisan-Seed Production In Hybrid Rice
Seed Production
  • For economic feasibility and commercial viability of rice hybrid technology, development of an efficient and economic seed production package is a pre-requisite.
  • Hybrid rice seed production involves several technical skills, which have to be managed successfully to obtain an acceptable yield level of 1.0 to 1.5 tons/ha.
Some of the aspects, which need to be standardized in hybrid rice seed production, are as follows
  • Obtaining proper synchronization of flowering between two parental lines,
  • Determining optimum row ratio,
  • Factors promoting out-pollination rate,
  • Appropriate dose and stage of GA3 application,
  • Precise timing and frequency of supplementary pollination.
  • Effective rouging at right stage to maintain high purity.
  • Careful and meticulous handling during harvesting, processing and packing.
  • At present two approaches, viz.,Three line system and Two line system are being followed in India for heterosis breeding in rice.
Three line system there would be need to produce three lines namely,
  1. Cytoplasmic male sterile line,
  2. Maintainer line (or) B-line, and
  3. Restorer line (or) R-line.

Two line system

  • B-line production is not needed.
  • The optimum package for hybrid seed production and CMS multiplication is given below,
Activity Particulars
Seed rate Seed parent 15 kg/ha,
Pollen parent 5 kg/ha
Nursery Sparse seeding to ensure multi-tillered (M-5) seedlings in 25 days.
Row ratio 2B : 6A, for CMS multiplication, 2R : 8A, for hybrid seed production.
Number of seedlings/hill Two seedlings/hill for seed parent,
Three seedlings/hill for pollen parent.
Spacing B/R to B/R 30 cm
B/R to A 30 cm
A to A 15 cm
GA3 application 45 g/ha at 5.0 % heading in two split doses on consecutive days
Supplementary pollination Twice a day at peak anthesis during flowering phase.
Rouging During vegetative phase based on morphological characters and twice during and after flowering based on floral characters etc.
Seed yield 1.5 2.0 tons per ha

Two line method or PGMS and TGMS System
  • Chinese rice scientists have been explored new technological approach to replace the CMS System and raise the yield ceiling claims in hybrid rice. So far the most successful is the development of 2-line method hybrid rice. The method is based on the 2 new kinds of rice genetic tools viz., Photosensitive (PGMS) and Thermo-sensetive (TGMS) genetic male sterile lines which have been developed successfully in China. Male sterility is mainly controlled by 1 or 2 pairs of recessive nuclear genes and has no relation to cytoplasm.
The advantage of the system over the above(CMS)
  1. Maintainer lines are not needed. The PGMS lines( under long day length) and TGMS lines( under high temperatures) show complete pollen sterility and can thus be used for hybrid seed production. Under shorter day length or temperate conditions, they show almost ,normal fertility and can be multiplied by selfing.
  2. Choice of parents for development of heterotic hybrids is greatly broadened. Studied showed that more than 98% of varieties tested can restore such male sterile lines.
  3. In addition, thePGMS and TGMS genes can be transferred easily to almost any rice lines with desirable characteristics.
  4. Therefore no negative effects due to sterile cytoplasm and the unitary cytoplasm situation of WA will be avoided.

 
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Ikisan - Released Rice Hybrids

Hybrids Released

Hybrid Parentage Duration (Days) Yield Of Hybrid (Tons/ha) Yield Of Check (Tons/ha) % Increase Over Check
APHR-1 IR 58025 A/ VAJRAM 130 - 135 7.14 5.27 (Chaitanya) 35.4*
APHR-2 IR 62829 A/ MTU-9992 120 - 125 7.52 5.21 (Chaitanya) 44.2*
MGR-1 IR 62829 A/ IR 10198 110 - 115 6.08 5.23 (IR-50) 16.2**
KRH-1 IR 58025 A/ IR 9761 120 - 125 6.02 4.58 (Mangala) 31.4*
CNRH-3 IR 62829 A/ AJAYA 125 - 130 7.49 5.45 (Khitish) 37.4 @
DRRH-1 IR 58025 A/ IR 40750 125 130 7.30 5.50 (Tellahamsa) 32.72 *
KRH 2 - 130-135 7.4 6.10(Jaya) Karnataka (U.P)
ADTRH I - 115-120 6.4 4.90(ASD18) Tamilnadu
CORH 2 - 120-125 6.25 5.20(ADT39) Tamilnadu
Narendra - 125-130 6.15 4.94(sarjoo 52) U.P
Telangana, Rayalaseema and uplands of coastal Andhra.
* =
Tamilnadu for May/June and September/October planting.
** . =
Irrigated areas of Karnataka.
*** =
For Boro season in West Bengal.
@ =

 
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