ES TI MA TION OF GE NETIC VARI ABIL ITY AND HERITABILITY PA RAM E TERS IN EARLY
GEN ER A TION CLONES OF SUG AR CANE (
Saccharum spe cies
Complex.)
Arvind Singh Negi, S.P. Singh, A.S. Jeena1, K.A. Khan
De part ment of Ge net ics and Plant Breed ing, G.B.P. Uni ver sity of Ag ri cul ture and Tech nol ogy, Pantnagar 263145, Uttarakhand 1E-mail : dr.asjeena@gmail.com
ABSTRACT
Early generation clones selected from Fifty-six bi-parental progenies of sugarcane alongwith seven check varieties were evaluated in an augmented block design II. Data were recorded on fourteen different morphological character including juice quality parameter and yield attributes. Statistical analysis revealed that in general, PCV was higher than both GCV and ECV for all the characters studied. CCS yield exhibited highest GCV followed by Single cane weight, Germination percent and Cane yield. CCS yield exhibited highest PCV followed by Cane yield and Germination percent. The highest estimated heritability (broad sense) value was obtained for cane diameter and single cane weight. Moderate heritability estimates were recorded for average inter-nodal length, germination percent, CCS yield, number of millable canes, cane yield and average numbers of internodes, while the heritability estimates were low for remaining characters. Genetic advance estimate is the improvement in the genotypic value in the new population in contrast to base population. The genetic advance as percent of mean for various characters varied from 1.2 % for juice purity per cent to 26.02 % for single cane weight. The genetic advance was high for single cane weight, CCS yield, germination percent, moderate for cane yield, average inter-nodal length, cane diameter, cane height and estimate were low for average numbers of internodes, number of tillers, juice brix percent, juice sucrose percent, CCS percent, number of millable canes and juice purity percent. Characters namely germination percent, number of millable canes, cane diameter, average inter-nodal length, single cane weight, cane yield and CCS yield were under the influence of additive gene effects and selection would be effective for the improvement of these characters.
Key words : Saccharum, sugarcane, vari abil ity, heritability, ge netic ad vance.
Sugarcane (Saccharum spp. Complex) is grown for white sugar and gur production and is an important dependable crop of economic sustenance. Sugar is the major product of sugarcane. The domestic demand of sugar is rotating around 22-23 million tonnes annually, where as the production of sugar in India during last 5 years is rotating around 24.3 to 26.3 Million ton. The total cane acreage for year 2016 was estimated to be 4.95 million hectares and sugar production estimated to be 352.16 million tonnes (1). The first Indian commercial hybrid cane Co 205 was an inter-specific hybrid between S. officinarum (Vellai) and S. spontaneum (Coimbatore) (2). Subsequently S. barberi, S. sinense and the wild species S. spontaneum were utilized, along with S. officinarum for evolving commercial hybrids in India (3). The present day varieties have a narrow genetic base with only eleven S. officinarum and two S. spontaneum clones (4). The knowledge of variability is desirable for a breeder before making any selection program. The two useful parameters: Genetic variability and heritability can help the breeder during different stages of crop improvement. Successful breeding program largely depend on the extent of genetic variability and heritability for important economic traits in early generation populations. Only the estimate of heritability a provides no indication of the amount of progress expected from selection, the heritability estimate along with genetic advance is needed in predicting resultant effect from selecting the best
individuals (5). Keeping the above in view the present investigation was conducted with the objectives of estimating the genetic parameters for different morphological and juice quality characters among early generation sugarcane clones of bi-parental crosses.
MATERIALS AND METHODS
The experimental comprised of Fifty six early generation clones of bi-parental crosses of sugarcane alongwith seven check varieties. These clones were planted in four blocks in an augmented block design II fashion at Norman E Borlaug Crop Research Centre, G.B.Pant University of Agriculture and Technology, Pantnagar during autumn 2015-16. Each clone was allotted to a single row plot measuring 3.0 m long with plot to plot spacing of 0.90 m. The data were recorded on germination percent (45 days after planting), numbers of tillers (‘000/ha) at 120 days and numbers of millable canes (‘000/ha) at 300 days on net plot basis and converted to thousand per hectare. For cane characteristics, cane height (cm), cane diameter (cm), single cane weight (kg), average number of internodes and average inter-nodal length (cm) were recorded at time of harvest. For juice characteristics, brix percent, sucrose percent in juice, juice purity percent and commercial cane sugar (CCS) percent were recorded at 12 months. Finally yield characters viz., cane yield (t/ha) and commercial cane sugar (CCS) yield (t/ha) per plot were recorded at time of harvest and calculated on hectare basis. The sucrose percent in juice was noted for
corresponding values of the brix and pol reading using Schmitz table (6)
Juice purity percent was calculated at 12 months using formulae
Purity %=Juice Socrose Juice Brix
Commercial cane sugar (CCS) percent at 12 months and CCS yield (t/ha) at harvest stage was calculated using formulae
CCS %=[S-(B-S)´0 . 40] ´0 . 73
Where,
S = Sucrose percent in juice.
B = Brix percent in juice.
CC yield (t/ha) =
Available sugar (%) in cane Cane Yield (t / ha)
100 ´
The data obtained were subjected to statistical analysis as suggested for augmented design-II (7) and as described by (8). Both genotypic and phenotypic coefficient of variability was computed for each character as per method suggested by (9). Heritability (h2bs) (10) and genetic advance as percent of means were estimated and categorized as low, moderate and high as suggested by (5).
RESULTS AND DISCUSSION
Analysis of variances revealed significant differences among clones for the characters namely germination percentage, cane diameter, single cane weight and
average inter-nodal length (Table 1). There were significant differences for germination percentage, number of tillers, canes height, cane diameter and average inter-nodal length for checks. In general the estimated values of PCV were higher than GCV for all the characters studied indicating role of environment on the performance of genotypes (Table 2). GCV, PCV and ECV values were categorized as low, moderate and high as indicated by (11).
From the analysis it was revealed that the estimate of GCV (15.83%) and PCV (21.99%) were moderate and high, respectively for germination percent. The heritability for the germination percent (51.78%) and the genetic advance as percent of mean (23.46 %) were also moderate. Moderate to high range of variation for germination percentage was observed by (12) while (13) reported high estimates of heritability along with high genetic advance (% of mean) for germination percentage. For the number of tillers the heritability in broad sense and genetic advance as percent of mean were 29.14 % and 9.36 % respectively. The estimates of GCV, heritability and genetic advance were low for number of tillers. However, high estimates of heritability along with high genetic advance (% of mean) have been reported by (13) but lower heritability and genetic advance in this case may probably be larger environmental interplay for this character. The heritability and genetic advance as percent of mean for number of millable canes per hectare were estimated as moderate (40.10 %) and low (1.45 %), respectively. Moderate estimates of heritability for NMC/ha also reported earlier (14). For cane height (cm), the heritability (29.61%) and genetic advance (11.46%) Table-1 : Analysis of variance of augmented block design for various characters in sugarcane.
Source of Variation
d.f. Germination Percent
No. of Tillers (‘000/ha)
No. of millable canes
(‘000/ha)
Cane height (m)
Cane thickness
(cm)
Cane weight (kg)
No. of internodes
Blocks 3 480.51** 763.39* 30.21 7350.29** 0.03 0.10* 27.81* Entries 62 46.27* 232.71 153.80 1974.07 0.08** 0.07** 8.28 Checks 6 123.96** 377.72* 63.85 3550.44* 0.08* 0.02 11.69 Varieties 55 59.88* 249.76 148.11 2009.82 0.08** 0.08** 9.55 Checks vs Vars 1 -1168.49 -1575.54 1006.84** -9450.42 0.12* -0.21 -82.16
Error 18 23.37 156.28 139.62 1246.79 0.02 0.02 5.53
Source of variation d.f. Inter-nodal length (cm)
Juice Brix %
Juice Sucrose %
Juice Purity %
CCS % Cane Yield (t/ha)
CCS yield (t/ha)
Blocks 3 3.39 5.02 2.77 3.57 1.11 843.42 22.71*
Entries 62 4.33** 4.99 4.46 3.99 2.31 485.88 15.87
Checks 6 7.38** 1.85 1.83 4.38 1.02 183.52 6.06
Varieties 55 3.60** 4.20 3.81 3.92 1.99 540.84 15.12*
Checks vs Vars 1 26.06** 67.43** 56.13** 5.38 27.71** -722.55 116.25
estimates were low to moderate while GCV (10.22%), PCV (18.78%) and ECV (15.76%) estimate were moderate. Low to moderate estimates of GCV and PCV coupled with moderate to high estimates of heritability for cane height had been reported by (14) and (15). High heritability (72.62%) and moderate genetic advance (15.04%) were recorded for cane diameter (cm). (16) also reported high heritability for this character. The estimates of heritability (62.12%) and genetic advance as percent of mean (26.02 %) were high for single cane weight (Kg). Moderate to high coefficient of variation and high heritability and genetic advance as percent of mean for this character had been also reported by(12). Higher expected genetic gains for cane weight were also reported by (17).
The heritability (33.31%) and genetic advance as percent of mean (10.20%) estimates were moderate for average number of inter-nodes, however low heritability and genetic advance as percent of mean had been reported for average number of inter-nodes by (16). For average inter-nodal length, the heritability (55.26%) and genetic advance as percent of mean (16.58%) were moderate. The heritability and genetic advance as percent of mean estimates were moderate in accordance to earlier findings of (16). The estimate of heritability (20.75%) and genetic advance (4.66 %) were low for juice brix percent. Lower estimate of GCV had been reported earlier for juice quality traits by (18) and (19). The estimates of heritability (18.09 %) and genetic advance as percent of mean (4.43%) were low for the juice sucrose percent. Lower GCV for juice sucrose percent had been reported earlier also by (19). For the juice purity percent the heritability (27.49 %) and genetic advance (1.20%) estimate were also found low. Lower estimate of heritability (17.09 %) and genetic advance as percent of mean (4.39 %) were revealed for
CCS percent. (20) have reported lower heritability values for CCS percent. The heritability (36.55%) and genetic advance as percent of mean (19.38 %) were moderate for cane yield. Low to moderate estimates of GCV and PCV coupled with moderate to high estimates of heritability and genetic advance as percent of mean for cane yield had be reported by (14). The estimate of heritability (44.12 %) was moderate for CCS yield, while genetic advance as percent of mean (24.48%) was high. The estimate of GCV was moderate but PCV and ECV were high for CCS yield. Moderate values of GCV coupled with high heritability and high genetic advance as percent of mean for CCS yield had earlier been reported by (14)
A critical perusal of PCV, GCV and ECV further indicated that, in general, both PCV and ECV were higher than GCV for all the characters. CCS yield exhibited highest GCV (17.89%) followed by Single Cane weight (16.03%), Germination percent (15.83%) and Cane yield (15.57%). However, lower values of GCV were exhibited by Juice purity percent (1.12%) and number of millable canes (3.52%). CCS yield (26.93%) exhibited highest PCV followed by Cane yield (25.74%) and Germination percent (21.99%). Lower PCV was exhibited by Juice purity percent (2.13 %) and Cane diameter (10.05 %). It’s explicated from the results that environmental variations contributed most to phenotypic variability. (16) reported high GCV for millable cane, cane yield and sugar yield and low GCV for number of inter-node, cane diameter and sucrose percent They also recorded high phenotypic coefficients of variation for sugar yield, cane yield, millable cane and moderate PCV for cane height. High GCV and PCV offers better scope of selection of these characters as their phenotypic expression would be good indication of the genotypic potential. Genotypic coefficient of Table-2 : Variability and heritability parameters of different characters in sugarcane.
CHARACTERS GCV% PCV% ECV% H2(b) in % GA as % of
mean
Germination per cent 15.83 21.99 15.27 51.78 23.46
No. of tillers (‘000/ha) 8.42 15.59 13.13 29.14 9.36
NMC (‘000/ha) 3.52 17.55 17.20 40.10 1.45
Cane height (cm) 10.22 18.78 15.76 29.61 11.46
Cane diameter (cm) 8.57 10.05 5.26 72.62 15.04
Single Cane weight (Kg) 16.03 20.33 12.51 62.12 26.02
Avg. No. of internodes 8.58 14.86 12.13 33.31 10.20
Avg. Inter-nodal length (cm) 10.89 14.57 9.74 55.26 16.58
Juice brix Percent 4.97 10.90 9.71 20.75 4.66
Juice sucrose per cent 5.06 11.89 10.76 18.09 4.43
Juice purity per cent 1.12 2.13 1.81 27.49 1.20
CCS per cent 5.16 12.48 11.36 17.09 4.39
variation alone is not a correct measure to know the heritable variation present and should be considered together with heritability estimates. (14) reported low estimates of GCV and PCV for cane length, cane diameter and HR brix, moderate values of GCV and PCV for cane volume, number of millable canes per plot and CCS yield in clonal stages and low to moderate estimates of GCV and PCV for sucrose, purity per cent and cane diameter, single cane weight, cane length and cane yield.
The concept of heritability (broad sense) plays a vital role in formulating breeding plans for crop improvement. The fraction of total variation which is heritable has been termed as coefficient of heritability in broad sense (10) or degree of genetic determination (21). It gives an indication of repeatability of performance if selection is practiced for the particular character. The concept of heritability (broad sense) is useful in determining the relative influence of genotype and environment to the total phenotypic variations. The highest estimated heritability (broad sense) value was obtained for cane diameter (72.62%) and single cane weight (62.12%). Heritability estimates in broad sense was moderate for the characters namely average inter-nodal length (55.26%), germination percent (51.78%), CCS yield (44.12%), number of millable canes (40.1%), cane yield (36.55%) and for average numbers of internodes (33.31%), while the estimates were low for cane height (29.61%), number of tillers (29.14 %), juice purity per cent(27.49 %), juice brix percent (20.75 %), juice sucrose percent(18.09 %) and CCS percent (17.09 %). (16) reported high heritability for stalk diameter and moderate for cane yield and number of millable canes. High broad-sense heritability also reported by (17) for number of millable canes, single stalk weight, stalk diameter and stalk height which supports the present findings.
The dynamic question of effective population size for improvement in character(s) for which selection is practiced have always been a matter of concern for plant breeders. For meeting such questions, the heritability is considered like a measuring rule when expressed in terms of genetic advance. Genetic advance is the most useful estimate as it is the improvement in the genotypic value in the new population in contrast to base population.
The genetic advance as percent of mean for various characters varied from 1.2 % for juice purity per cent to 26.02 % for single cane weight. The genetic advance was high for single cane weight, CCS yield, germination percent, moderate for cane yield, average inter-nodal length, cane diameter, cane height and estimate were low for average number of internodes, number of tillers, juice brix percent, juice sucrose percent, CCS percent, number of millable canes and juice purity percent. High expected genetic gains recorded for stalk weight and number of millable canes had earlier been reported by (17). High
genetic advance as percent of mean for tillers followed by germination percent, inter-nodes per stalk, shoots and stalk height was reported by (13). (22) and (20) also reported high expected genetic gain for stalk weight. (23) and (24) also reported high genetic advance for CCS yield. These earlier finding supports the present finding indicating characters namely germination percent, number of millable canes, cane diameter, average inter-nodal length, single cane weight, cane yield and CCS yield were under the influence of additive gene effects and selection would be effective for the improvement of these characters.
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