Screening For Salinity Tolerance In ugarcane, SBI

SCREENING FOR SALINITY TOLERANCE

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Sugarcane Breeding Institute QndianCouncil of Agricultural Reeearch) Coimbatore 641 007

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2010

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Screening for Salinity Tolerance in Sugarcane

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creening methodology for salinity tolerance depends on the relative tolerance of the crop and sensitivity of the crops' pheno phases to salinity.

Sugarcane is grouped as moderately sensitive crop to salinity. Cultivars of the same crop at times show stage sensitivity to salinity. In general, seedling response is inconsistent for the subsequent growth stages. Nevertheless, it has ,.; to be borne in mind that soil salinity doesn't change drastically over seasons. A -. minor reduction in EC (electrical conductivity) and pH of soil occur during rainy periods due to leaching of soluble salts. Considering these facts and response of the crop, suitable screeningmethodology has to be adopted.

General methods of scfeehingfor salt tolerance include

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1. Selection based on germination percent of seeds in saline medium.

2. In uitro selection for salt tolerance.

3. Screening in simulated condition at desired level of stress.

The salts used to induce salinity vary from laboratory to laboratory, crop and method used. A majority of screeningprocedure involve NaCl as single salt. The limitation in using NaCl alone is that the expression of the crop varies from real field situation and hence, mixture of salts has been advocated for representing few major salts contributing for soil salinity.

Scr,e.eningwork at Sugarcane Breeding Institute Micro plots facility was created for the purpose of screening advanced breeder's material and commercial varieties (Fig.1). Individual micro plot measures 3.25 length x 2.65 width x 3.0 depth in metres. In total there are 48 such plots. Equal number of salinity and control plots are maintained for comparison purpose. In the treatment plots, soil is salinised prior to planting and till harvest the EC of the saturated soil extract is maintained at 8 d~m-'.

The ' salinity treatment is effected by irrigating with 1%salt solution of NaCl: CaC1,: NqSO, in the ratio of 2:2:1.The soil EC is monitored at regular intervals and the treatment is effected as and when required. The control plots are irrigated with normal irrigation water.

Rating for tolerance The harvest index proposed by Donald has been one of the criteria to assess the potential yield and stability in different environments. In sugarcane, a similar method was tested for ten commercial cane varieties and found suitable under drought condition. A similar approach was found useful in rating commercial genotypes for salinitytolerance. The relative performance of the genotypes in terms of cane yield and sugar yield is assessed by plotting the cane yield under salinitytreatment againstyield under normal condition.

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Similarly for sugar yield also, relative performance is worked out. Genotypes with better cane and sugar yield in normal as well as salt treatment fall in quadrant- I and are considered as tolerant types.

About 1200genotypes including advanced breeders material, germplasm material, species and somaclones were screened so far. Saccharum species screened for salinity tolerance is presented in table 1. Among the popular varieties tested, Co. 86011, Co 7717, Co 7219, Co 8208, Co 85004, CoC 671, Co 6806, Co 94008, Co 85019, Co 94012, Co 97008 and Co 99004 were found suitable for salt affected soils (Fig. 2 & 3). Several promising genotypes have also been identified as tolerant types

Tablel: Saccbarum species screened for salinity toleraace S.No.

Species

Total number screened

No. of tolerant types

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Saccharurn oflcinarum

346

113

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Saccharurn robusturn

59

15

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Saccharurn barberi IND clones

39

12

155

21

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Fig. 1. Screening fbr W t y toltmuwe ln m i m plom

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Fig. 2. Co 94012 tolerant type

Fig. 3. Co 97010 - sensitive type

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Extension Publication No. 181 (2010) Sdpt by

: Dr. S. Vasantha, Dr. R. Gomathi 8 Dr. P. Rakkiyappan

Edited by

: Dr. T. Rajula Shanthy

Published by

: Dr. N. Wjayan Nair, Director, Sugarcane Breeding Institute, Coirnbatore 641 007 : Tel. 0422 - 2472621,2472723, Fax: 2472923

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Print by

: Abi Print, Coimbatore.