MIME-Version: 1.0 Content-Location: file:///C:/DE821653/Lead13.htm Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii" Problems and Prospects of System of Rice Intensification (SRI) metho= d

Problems and Prospects of System of Rice Intensification (SRI) method

 

M. Ganesh, N. Manohar Reddy ,L.V.Subba Rao and K= . Radhika

National Seed Project, Acha= rya N.G. Ranga Agricultural University

Rajendranagar= , Hyderabad-500 030, India

 

   &nb= sp;        The System of Rice Intensification (SRI) developed in Madagascar is a new methodolo= gy for rice culture. The main features of this system are transplanting of young seedlings singly in a square with wide spacing using organic fertilizers and keeping the soil moist during the vegetative phase. This system offers opportunities to researchers and farmers to expand their understanding of y= ield potential already existing in the rice genome (Stoop et al., 2002, Uphoff et al., 2002). Significant changes occur in plant structure and functioning in yield and its components under SRI cultivation. Recently, SRI generated a lot of interest and discussion among researchers, farmers and policy makers in Ind= ia resulting in polarised views. Some proponents c= laim that SRI would revolutionize the rice production while others view it as a myth. However, further systematic inter-disciplinary research efforts are required to assess the potential benefits and limitations of SRI adoption in diverse climatic and socio-economic environments.

 

SRI Methodolo= gy

 

Nursery prepa= ration

 

1.       The rice seeds should first be soaked in water for 24 hours. Irregular and float seeds should be discarded.

2.       Then the seeds should be put in a sack and placed in a warm pile or in a hold in= the ground to have the required warmth. Cover the sack completely with paddy st= raw and leave it for 24 hours for warming of the seeds.

3.       The nursery bed should be prepared very near to the main field to reduce the transport time between removal of seedlings from the bed and their transpla= nting in the field.

4.       Well decomposed compost/FYM should be applied to the soil of the nursery bed at a rate of 10 kg/m2. Prior to sowing a thin layer of FYM and black = soil has to be spread on the bed to give the seed good nutrient material for the= ir germination and growth.

5.       Pre-germinated seeds should be broadcasted on the nursery bed at a rate of about 2 kg for = 40 square metres (sufficient to plant in one acre)= and then seed has to be covered with a thin layer of soil and FYM mix.

6.       The nursery bed should be watered regularly to maintain moderate level of moist= ure. The soil should not be saturated or kept continuously wet.

7.       Transplanting should be done at 8-12 days age when the seedlings have just two leaves. Du= ring rabi, when temperatures drop down it t= akes about 18-20 days for the seedlings to attain two leaf stage.

 

Main field preparation

8.       After applying good amount of organic fertilizers the main field has to be plough= ed and puddled thoroughly with rotavator.

9.       The field has to leveled perfectly allowing drainage channels all along the edges of the field to ensure proper water control.

 

Transplanting=

 

The seedlings should be carefully removed from the so= il with a trowel rather than being pulled out to minimize the trauma. It is important that the seed sac remains attached to the infant root. When transplanting the seedling, the root should be horizontal, so that the plant’s shape (including the root) is like the letter ‘L’= and the root tip grows downward easily and quickly. Seedlings should be transplanted very quickly (within half an hour) after removing from the nursery. The roots should not be allowed to dryout. A wet gunny cloth may be placed on the seedlings during transport from nurser= y to main field to avoid drying on exposure to Sun. The nursery has to be removed from the bed and transported as and when required depending on the progress= of transplanting.

 

The seedlings have to be planted singly at a spacing = of 25 cm x 25 cm. To plant in a uniform square pattern, one method is to use r= opes tied between sticks and holding on the edges of the field. The ropes should= be marked or knotted at similar intervals to match the width of the rows to ha= ve uniform spacing and facilitate weeding with a rotary w= eeder. A specifically made rake can be used alternatively which makes impression of lines on the surface of the field for planting seedlings at intersections of the lines.

 

Water managem= ent

The field should be watered about a week after transplanting (depending on the soil moisture) and then first weeding with rotary weeder (both directions) should be done = after the soil is sufficiently moist. The best time to give water to the field is before periodic weedings. During the growth pha= se, water should be applied to the field only for the purpose of weeding. The f= ield may be allowed to dry for soil aeration. Once the crop reaches the flowering stage, a thin film (1-2 cm) of water should be maintained in the field. The field should be dried completely about 15-20 days before harvest.

 

Weeding

Weeding has to be done regularly depending on the need starting from 10 days after transplanting with a rotary weeder in both the directions up and down rows and across them. As a result, the w= eeds are trampled and soil is churned. This should be done until the growth of plant’s canopy makes it difficult to pass the we= eder between them.

 

Pest and disease management

As the field is kept moist in SRI cultivation, the pe= st and disease problems are comparatively less as compared to normal method wh= ere rice is grown under sub-merged conditions. Reports from the experimentation= of SRI method in various countries indicate that there were fewer pest and dis= ease problems with this method.

 

Harvest

SRI rice is harvested just= like normal method with an advantage that there is almost no lodging, due to pro= fuse rooting and ‘U’ type of tillering l= eading to sturdy plant growth.

 

Reports on increased yields with SRI method

Reports on increased yields are available today from = Madagascar where it was practiced initially. There are conforming results from 18 countries including China and Peru with average yields of 7-8 tonnes/ha and from atleast four countries with yields over 15 tonnes/ha (Table = 1). In India, SRI was first introduced in Andhra Pradesh in 2003 by Acharya<= /st1:PlaceName> N.G. = Ranga Agricultural University, Hyderabad. Nearly, 10,000 farmers attempted this method in the kharif, 2003 and reported increased yields ranging from 50-100% over normal method. This system was found effective in almost all the districts = of the state on varying types of soils, except soils having salinity. SRI is starting to spread in Tamil Nadu state where the extension service expects that half of the Cauvery Delta will be under SRI cultivation in the near future.

 

Results at DA= ATT centres and NSP in Andhra Pradesh

The farmers were apprehensive to adopt SRI in the beginning particularly with regard to planting tiny seedlings and weeding w= ith rotary weeder at regular intervals. But all the farmers in 18 locations adopted the practice without much difficulty. The C= hief Minister and Minister for Agriculture, Andhra Pradesh h= ave observed the trials in farmers’ fields and research centres. The Government of Andhra Pradesh desires the advantages of SRI to be explor= ed, advising extension staff to verify the results and popularize SRI among the farming community as it saves water and reduces cost of cultivation.

 

An observation trial, conducted at National Seed Proj= ect, Rajendranagar, Hyderabad with BPT-5204 durin= g 2003 and 2004 (khar= if season) revealed that SRI method = has an yield advantage of 24% as compared to conventional method. The crop has attained maturity earlier by 6 days.

 

Mean data on important quantitative characters at NSP, Hyderabad

 

Method

No. of ear bearing tillers

No. of grain per panicle

Panicle length (cm)

Maturity (days)

Yield

(t/ha)

SRI

28

166

21.0

139

7.1

Conventional

10

162

21.4

145

5.7

 

Different mechanisms contributing to higher yield with SRI method

 

The System of Rice Intensification (SRI), developed by Fr. Henri de Laulanie, in the 1980s in Madagascar= , offers opportunities for improving rice production around the world in different situations. It is not a methodology limited to certain growing environments, not a “niche” innovation as suggested by Dobermann (2003). Rather, it is being used increasing= ly around the world in a variety of agro-ecosystems, with good results on almo= st all soil types and on larger-scale operations as well as on small farms (Uphoff, 2004). The most important cause for hesitation about SRI is the fact that its results are highly variable, both within and between countries which may be attributable to the methods not being used as recommended as well as due to differences in the skill in using the methods= and diversity of soil microorganisms in a tested environment.=

 

SRI achieves improvement in yield and factor producti= vity by changing some of the plant, soil, water and nutrient management practices (Stoop et al., 2002). The pract= ice of SRI promotes greater root growth, more biological activity which is not vis= ible ultimately leading to increased productivity with low cost (Uphoff et al., 2002).

 

The three basic concepts of SRI are:

-&nb= sp;            =          Transplanting very young seedlings (<15 days) which preserves plant’s potential = for tillering and root growth that is reduced by later transplanting. Careful transplanting promotes rapid resumption of growth.

-&nb= sp;            =          Wider spacing with one plant per hill paves way for profuse root and tiller growth achieving the border effect in the entire field.

-&nb= sp;            =          Keeping the soil moist and aerated during the vegetative growth period makes the ro= ots to have access to both oxygen and water. Under continuous hypoxic condition= s, rice roots degenerate with as many as 75% dysfunctional by panicle initiati= on (Kar et al= ., 1974).

-&nb= sp;            =          The other biological processes that could be increasing rice yields with SRI management of plants, soils, water and nutrients are:

-&nb= sp;            =          Under alternate flooding and drying of soils, aerobic and anaerobic bacteria and = mycorrhizal fungi have an opportunity to contribute to plant growth (Brimecombe et al., 2001). Under these conditions, there is increased N fixation (Magdoff and Boul= din, 1970) and P solubilization (Turner and Haygarth, 2001).

-&nb= sp;            =          The larger root system enables the plants indirectly to produce more N in their root zone by exuding photosynthates made from atmospheric CO2 in the rhizosphere (= Badalucco and Kuikman, 20= 01).

-&nb= sp;            =          Many species of bacteria and fungi produce phytohormones in the rhizosphere – auxins, cytokinins, ethylene, etc., that regulate and p= romote root growth (Arshad and Fr= ankenberger, 2001).

 

Benefits of S= RI cultivation

SRI cultivation results in higher profitability due to lower costs of production accompanying higher yield and increased productiv= ity for land, water and capital. The nutrient availability through organic and green manures and less pests and diseases curtails the environmental pollut= ion and improves the soil health through biological activity. The cost associat= ed with nucleus and breeder seed production can be minimized due to use of sma= ll quantity of seed and genetic purity of the varieties is perfectly maintaine= d as only fewer plants need to be observed. The farmers too have a good opportun= ity to produce their own seed.

 

Problems asso= ciated with SRI

There are certainly some problems on the use and adop= tion of SRI. The foremost constraint is perfect land leveling to plant 2 leaf st= age seedling followed by&n= bsp; good water control and regulation. Many farmers do not have w= ater control as most of the irrigation is from field-to-field distribution. The second constraint is requirement of more labour= for planting and operation of rotary weeders. The o= ther major requirement is motivation and skill. The farmers have to become more knowledgeable with regard to management of SRI. The other apprehensions are that SRI could lead to soil depletion and non-availability of organic manur= es in sufficient quantities.

 

Conclusion

The System of Rice Intensification is still evolving, it is more a set of ideas than a completed technology. It is only since 1999 that institutions outside Madagascar have taken an interest in SRI in evaluating its potentials and understanding the results. The data on SRI have not been collected in standard format because= it is being undertaken by a diverse set of NGOs, government agencies, research= centres, farmers and individuals. Improvement in the methods need to be made to suit the local conditions by the farmers as well as researchers. There are many interesting issues to be tac= kled by researchers in soil microbiology, in plant-soil-water relation, in mechanisms for phenotypic expression of genetic potential, in selection and breeding for best varieties suitable for SRI conditions. Hopefully, with the concerted efforts of all disciplines and passage of time, SRI methodology m= ay improvise further and becomes a boon to the rice growing farmers.