Progress of Rice Improvement program in Sri Lanka

Introduction

At the turn of the 20th century, rice yields less than 1 t/ha (Elliot,1913)

Total annual rough rice production in the country less than 0.25 million Mt

A ten-fold increase in national annual rough rice production (0.25 million Mt to 2.5 million Mt) from 1940’s to 1980’s due to varietals improvement

At present day average yield 4.2 Mt/ha

Previous to 1930’s

Little rice research & varietals improvement program

Large number of varieties(300 varieties) available

This indicates the low level of improvement

The average yields around 0.72-0.92 t/ha (14-18 bushels/ac ) (E. Elliott in 1913)

cont… The cultivars grown by farmers traditional types

These traditional varieties not pure varieties but a mixture of several varieties

In 1922 Department of Agriculture tried to improve the quality of seed paddy by purifying the land races

As first step, popular land races purified and a set of pure-line varieties selected

Commonly cultivated varieties in 1930’s & earlierAge class (month) Name of Variety

5-6 Podiwee,Muthusamba, Panduruwee4-4 ½ Murungakayan,

Vellai Illankalayan3 ½ Heenati,Vellai Perunel3 Pachchaperumal

Pure line selection After 1930 recognize the need of varietal

improvement program In 1940’s pure line selection used to improve

varieties Number of selections narrowed down to few best

lines from the previous selections Those are – Podiwee A-8(5-6 m) Murungakayan 302 (4-4 ½ m) Vellaiperunel 28724 (3 ½ m) Pachchaperumal 2464/11 (3 m) Susceptible to leaf blast with the added fertilizer

Introduction

In 1950’s several varieties introduced from other countries

E.g.: Ptb 16 (5-6 m) –from India ‘Mas’,‘Remadja’ and ‘Sigadis’(4-4 ½ m) –

from Indonesia

Moderately respond to added fertilizer But susceptible to leaf blast disease (except ‘Sigadis’) This introduction not successful

Hybridization

This national rice breeding program initiated at the Agricultural Research Station at MahaIlluppalama

In 1952 shifted to Batalagoda

(Central Rice Breeding Station of DOA) Hybridization program-by making crosses

between introduced &local varieties

Cont…

Referred as Old Improved Varieties (OIV) H series (Early 1957)

H-4 (4-4 ½ m),H-7 (3-3 ½ m), H-9 (5-6 m),H-10(3 m) H varieties gained popularity in the 1950s and

1960s.

Through H varieties the national average yield increased up to 2.0 t/ha (40 bushels/ac)

Production increased 1.08 million Mt/year (52 million bushels/year )

Characteristics of OIV

Resistant to leaf blast disease Moderately respond to added

fertilizer Tall weak stems Long and drooping leaves Lodging severely with heavy

use of fertilizer

Highest recorded experimental yields of pure lines and new hybrid varieties

Age class (m) Variety yield (bu/ac)5-6 pbt 16 80

H-9 1214-4 ½ M-302 80

H-4 1423 ½ VP 28724 71 H-7 863 H-10 95

Breeding for lodging resistance Major problem with OIV s - lodging Plant type changed from tall type to dwarf and

intermediate height with ability to tiller moderately. In 1960 Thaiwan create new plant type called

Taichung Native 1

(Short sturdy stems, short, narrow, dark & green leaves)

In 1967 International Rice Research Institute(IRRI) develop first new dwarf variety -IR 8

Introduction of IR 8 & Taichung Native 1 failed

Cont… Incorporate gradually lodging resistance to local

types

Under this program in 1960 rice breeders developed New Improved Varieties (NIV).

They were the 'Bg' varieties from Batalagoda, 'Bw' varieties from Bombuwela, 'At' varieties from Ambalatota, 'Ld' varieties from Labuduva

E.g.: BG 11-11 & LD 66 -yield potential -7.2Mt/ha(140 bu/ac)

Breeding for Pest resistance Problem of NIV low level of

resistance In 1975 release BPH

resistance variety-BG379-2 (4-4 ½ m)

In 1978 release gall midge resistance varieties

BG 400-1(4-4 ½ m)

BG 276 (3 m)

New Improved varieties In 1980s NIV gained popularity and cultivated in

more than 95% of the paddy extent in the country

Production increased up to 2.4 million Mt/year (115.75 million bushels/year) with an average yield of 3.3Mt/ha (64 bushels/ac)

However, attempts made to further increase the productivity level achieved in the 1980s not successful and yield levels stagnated for at least a decade

Average Yield of Paddy (Kg/ha)

New Improved VarietiesYear variety Yield (t/ha)

1979 Bw 100 (4-4 ½ m) 6.01980 Bg 400-1 (4-4 ½ m) 8.51981 Bg38 (6 m) 6.01982 Bg 380 (4-4 ½ m) 10.01985 Bg 450 (4-4 ½ m) 6.01986 Bg 350 (3 ½ m) 8.51987 Bw 451 (4-4 ½ m) 6.01992 Bw 452 (4-4 ½ m) 5.01994 Ld 355 (3 ½ m) 4.51997 Bg 357 (3 ½ m) 9.51998 Bg 359 (3 ½ m) 9.51999 Bg 305 (3 m) 8.0

New Plant Type

The International Rice Research Institute (IRRI) began developing the new plant type (NPT) rice through ideotype breeding approachesin 1989 (Khush 1995)

Develop an NPT with a yield potential 20–25%

higher than that of existing semi dwarf rice varieties

The NPT designed based on the new morphological traits Which easier to select than physiological traits in breeding programs.

The New Plant Type Low tillering capacity (3 to 4 tillers when direct-

seeded) Few unproductive tillers 200 to 250 grains per panicle A plant height of 90 to 100 cm Thick and sturdy stems, Thick leaves Dark green and erect leaves A vigorous root system 100 to 130 days growth duration Increased harvest index (Peng et al 1994).

Future Challengers in Rice improvement Present Sri Lanka faced on several

problems

Salinity

Flooding

Climate change Have to improve varieties which can

tolerant for those problems

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