GENETIC VARIANCE AND PERFORMANCE OF SESAME MUTANTS FOR YIELD CONTRIBUTING CHARACTERS

In Bangladesh average sesame production is lower than other sesame producing country of the world, Therefore an experiment was conducted using five sesame M5 mutants along with the mother variety to observe their performances regarding seed yield and other yield attributes. Analysis of variance showed highly significant variations among the mutants and check for most of the characters. The mutant SM-07 required the shortest maturity period and produced the tallest plant and highest number of capsules plant-1 in each location and combined over locations, where as SM-01 and the mother variety Binatil-1 required the longest maturity period. Results over different locations also showed that the three mutants SM-06, SM-04 and SM-07 produced significantly higher seed yield (1477, 1449 and 1438 kg ha-1, respectively) which was 7.3, 5.2 and 4.4% higher than the mother variety Binatil-1 with seed yield of 1377 kg ha-1. This suggests that mutation techniques can be fruitfully applied to develop variety with higher seed yield and other improved agronomic traits of sesame.


INTRODUCTION
Sesamu indicum L. (Family Pedaliaceae) commonly known as sesame is an important oilseed crop.It is referred as 'queen of oilseeds' due to its regard by the users and owing to its oil quality [1].It is one of the most ancient crops in the world known to mankind, with archeological evidences dating back to 2250 and 1750 BC at Harappa in the Indus valley [2].Ironically, it is considered as an 'orphan crop' due to meager research efforts attributed to the fact that it is not a mandate crop for any international crop research institute [3].Sesame is mainly a crop of warmer areas including Asia and Africa, In Bangladesh the total production is 2970 metric tons [4,5].Average productivity of sesame has lowered ranging from 144 to 234 kg ha -1 compared to past 20 years which has led to a gap in the demand and the supply [6].It is an excellent rotation crop of cotton, maize, groundnut, wheat, and sorghum.It reduces nematode populations that attack cotton and groundnut [7].Its deep and extensive root system makes it an excellent soil builder.It also improves soil texture, retains moisture and reduces soil erosion.The left over composted sesame leaves also help in moisture retention of the soil making favorable conditions for planting the next crop.Considering the importance of sesame, development of higher yielding sesame variety is persistent demand.
For any plant breeding programme, creation of genetic variation followed by selection plays an important role in developing improved crop varieties.Therefore, genetic variations in useful traits are prerequisites for any crop improvement programme.Like other breeding proramme in sesame creation of variability transpires to be primary step to get desirable types.Mutation breeding has long been known as a potential technique to unlock additional genetic variability for supplementing conventional crop breeding methodology.Mutagenesis offers a unique scope for creating variation, as it may alter even those genes that are common to all the varieties of a species.Induced mutation has been extensively and successfully used for the improvement of many crops including oilseed crop like sesame.Henceforth an attempt was made to select desirable sesame mutant line with high yield potential.

MATERIALS AND METHOD
Seeds of sesame variety Binatil-1 were irradiated with 500, 600, 700 and 800 Gy doses of gamma rays using Co 60 gamma cell to create genetic variations.Irradiated seeds then sown to grow M1 generation at BINA, Mymensingh in 2011 for selecting desirable mutants in subsequent generations.Selection was made in each of M2, M3 and M4 generation based on desired agronomic traits.From M4 populations, five homozygous and true breed mutants namely SM-01, SM-04, SM-05, SM-06 and SM-07 were selected for further evaluation.These five true breeding mutants along with the mother variety Binatil-1 and check variety Binatil-2 were evaluated at three sesame growing areas of Bangladesh during 2017 following randomized complete block design with three replicates.Seeds were sown within first week of March 2017 maintaining unit plot size of 20m2 (5.0m × 4.0m) with a line spacing of 25cm and 6-8cm for plant to plant within rows.Recommended production packages like weeding, thinning and application of fertilizers, irrigation, pesticide etc. were done uniformly to ensure normal growth and development of the plants in each plot as and when necessitated.plant height, number of branches plant -1 , number of capsules plant -1 and number of seedscapsule -1 from 10 randomly selected representative plants from each plot at maturity.List of all the traits under study and their description of measurement have been presented in Table 1.The collected data were analyzed statistically according to the design followed using the analysis of variance (ANOVA) technique following Gomez & Gomez (1984).The mean values were compared by DMRT at 5% level of significance.Standard heterosis for each character was expressed as per cent increase or decrease of mutant over the standard variety (SV).Using formula suggested by a group researchers [8].The t' test was applied to determine significant difference of mutant means from respective standard parent values using formulae as reported in a study by a group researchers [9].The mean square of genotypic and phenotypic variances were estimated according to a study [10].

Serial
No. Traits Methods of measurement Days to maturity Plant height (cm) Branches plant -1 (no.) capsule plant -1 (no.)Seeds siliqua -1 (no.)Seed yield (kg/ha) The number of days from sowing to 70% siliquae turned into brownis color The height from the base to the tip of the plant Total number of primary branches plant-1 Total number of capsule with seeds in a plant Total number of seeds in a capsule Weighting the seeds produced in a plot and then converted into kg ha -1

RESULTS AND DISCUSSION
In M5 generation, the analysis of variance for different quantitative characters revealed that mean squares were highly significant for all the traits indicating the existence of high genetic variability among the mutants for yield and yield components (data was not presented here).In other words, mutation induced substantial genetic variability among the lines.Significant variations for different quantitative characters have also been reported in sesame earlier by Begum and Dasgupta 2015 and in other oilseed crops that's findings confirmed the present observation [11][12][13].The component of variant along with coefficient of variability and genetic parameter of some yield component of the studied genotype are present at Table-1.Seed yield showed the higher genotypic and phenotypic variability followed by capsule plant -1 .Capsule length showed minimum difference considering genotypic and phenotypic components of variance followed by branch plant -1 .The narrow differences between genotypic and phenotypic components of variance indicate those major portions of this phenotypic variance are genetic in nature.In this study capsule length showed higher broad sense heritability followed by capsule plant -1 .The lowest broad sense heritability was found in case of branch plant -1 .Higher genetic advanced was found in case of capsule length followed by seed yield.The lowest genetic advance was found in case of branch plant -1 followed by capsule length.Higher broad sense heritability along with high genetic advance is usually more helpful in predicting the resultant effect for selection of the best individual than heritability only.Here higher heritability with higher genetic advance was found for the characters seed capsules -1 , capsule plant -1 plant height and days to maturity.So this type of characters needs to be consider for sesame improvement.
Mean values of three individual locations for understand the performances of the studied genotype have been consider and presented in Table 2. Maturity period is the most important and frequently observed character which can be modified in oilseed using induced mutation.Significant differences were observed for days to maturity in different locations.At Magura, except SM-07 other mutants matured earlier then mother variety Binatil-1.Both Ishurdi and Magura, SM-07 required the shortest period of 85 and 84 days respectively to mature.At Ishurdi mutant SM-01 and check Binatil-2 took the highest maturity period of 89 days.Like other two location at Chapainawabganj, mutant SM-07 also required the shortest maturity period of 83 days having non-significant difference with other mutants while Binatil-1, Binatil-2 and mutant SM-01 required the longest duration 87 days.It is observed that, most of the mutants matured earlier than the mother variety.This result revealed that through induced mutation maturity period can be reduced.Induction of early maturity in the mutants of oilseed has been reported in some study on sesame which confirm the present result [14,15].
Plant height differed significantly when comparing the mean of locations.At Magura, mutant SM-07 produced the highest plant height (136cm) closely followed by SM-06 (134cm) while SM-05 produced the shortest plant of 116cm.At Ishurdi, SM-07 also produced the tallest plant (122cm) which was closely followed by mother variety Binatil-1(119cm) and mutants SM-04 and SM-05.Statistically non-significant plant height was obtained from SM-01 and SM-06 whereas SM-06 produced the shortest plant of 115cm.similar result was also obtained at Chapainawabganj.Sesame demonstrates indeterminate growth habit, which causes nonsynchronous maturity and very high plant height; these prevent mechanized harvesting.Shorter plant height is therefore an essential part of adaptation in modern agricultural systems with combine harvesting.Reducing plant height also improves lodging resistance, which is another problem in sesame cultivation.However, low plant height seems to be a disadvantage with respect to higher seed yield, because plants of greater height tend to bear more capsules and thus yield more seed.Development of shorter mutants in oilseed Brassica has been reported in studies [16,17].These results also conform that using induced mutation plant stature can be altered in oil seed crops.
The number of branches is one of the important selection criteria in sesame improvement programs because a higher number of branches enable bearing more capsules per plant and result in higher seed yield [18].In this study, all the mutant except SM-07 are uniculam type.At Magura, SM-07 produced the highest number of capsules plant -1 (87) closely followed by mutants SM-06 and SM-04 (74) and mother variety produced the lowest number (63) which was statistically similar with mutant SM-05 (61).Like Magura, both of Ishurdi and Chapainawabganj, SM-07 produced the highest number capsules plant -1 (75 and 85 respectively).In oilseed Brassica, as a consequence of mutagenesis reported higher siliqua number in developed mutants over their mothers [19][20][21].Significant differences were also observed for capsule length in different locations.On an average, mother variety Binatil-1 produced the highest capsule length which was significantly different with all other mutants but at Ishurdi, mutant SM-06 produced statistically similar capsule length that was 3.45cm whereas in Binatil-1 it was 3.93cm.A group researchers also find this type of result in his research work on sesame [22].
Like other character number of seeds capsule -1 differ significantly both in individual locations and combined over locations.At Magur, maximum number of seeds capsule -1 was obtained from mother variety Binatil-1(99) followed by mutant SM-05 (78) while mutant SM-04 produce minimum seeds capsules -1 .At Ishurdi, maximum number of seeds capsules -1 was obtained from mother variety Binatil-1(75) followed by check variety Binatil-2 (71) while mutant SM-01 produce minimum seeds capsules -1 (54) number.Similarly, at Chapainawabganj, Binatil-1 produced maximum seeds capsule -1 (96) followed by SM-06 (82) and mutant SM-01 produced lowest seeds capsules -1 that was 72 number.Baydar stated that capsule production is one of most important traits defining the ideal type of sesame plant; it has also been identified [18,23].Although produced the highest number of capsules, the seed yield of this genotypes was lower than the others or control because sesame's indeterminate character can cause non-mature capsule production at harvest time.
The mutants SM-07 produced the highest seed yield of 1456 kg ha -1 followed by SM-04 (1433 kg ha -1 ) and SM-06 (1431 kg ha -1 ) which was statistically similar to each other.Mother variety Binatil-1 produced the lowest yield of 1366kg ha -1 which was statistically identical with two other mutants SM-01 and SM-04, on the other hand check variety Binatil-2 produced seed yield of 1400 kg ha -1 having statistically significant different from all other mutants and mother check variety at Magtura.At Ishurdi mutants were also performed higher seed yields, the mutant SM-07 produced the higher seed yield of 1500kg ha -1 closely followed by the mutant SM-04 which produced 1492kg ha -1 of seed yield, like this at Chapainawabganj mutant SM-07 produced the higher seed yield of 1500kg ha -1 closely followed by mother variety Binatil-1 which produced 1458kg ha -1 of seed yield.Positive shift in mean values due to the enhancing effect of gamma-rays was also reported earlier by many research workers likes in sesame and rapeseed [21,24].In plant breeding, generation of genotypes having improved yield contributing characters is the main objective for achieving higher yield [25].In oilseed, the most important yield attributes responsible for the increased seed yield are the capsule number and seed number in capsule.Seed yield is a Data were taken on different morphological traits and yield attributes like Malaysian Journal of Sustainable Agriculture (MJSA) DOI : http://doi.org/10.26480/mjsa.02.2019.27.30RESEARCH ARTICLE GENETIC VARIANCE AND PERFORMANCE OF SESAME MUTANTS FOR YIELD CONTRIBUTING CHARACTERS Md.Saikat Hossain Bhuiyan 1* , Dr. M. A. Malek 2 , Md.Mohsin Ali Sarkar 3 Majharul Islam 4 , Md.Wasim Akram 5 = Genotypic component of variance, GCV = Genotypic coefficient of variance, VP = Phenotypic component of variance, PCV = Phenotypic coefficient of variance, h 2 b = Broad sense heritability and GA = Genetic advance

Table 2 :
Estimation of genetic component of variation for yield and yield contributing

Table 3 :
Mean performance of sesame mutant lines along with check varieties for different quantitative characters Note: Same letter(s) in a column for individual location/combined means/location means do not differ significantly at 5% level of significance.

Table 4 :
Standard heterosis for different yield contributing component of sesame mutant ** indicates significant at 1% level Compared with Check variety Binatil-2 at seed yield was decreased 1.12% in SM-01, 3.80% in SM-06 and 1.18% in SM-05.At the mutant SM-07 it increased 1.8% and 1.14% in SM-04 over check variety Binatil-2.