INDIAN JOURNAL OF PURE & APPLIED BIOSCIENCES

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Indian Journal of Pure & Applied Biosciences (IJPAB)
Year : 2020, Volume : 8, Issue : 2
First page : (303) Last page : (310)
Article doi: : http://dx.doi.org/10.18782/2582-2845.8061

Heterotic Potential for Green Cob Yield and Related Traits in Sweet Corn (Zea mays L. saccharata)

Ravikesavan, R.1* , Niji, M.S.1, Ganesan, K.N.1 and Chitdeshwari, T.2
1Department of Millets, Centre for Plant Breeding and Genetics
2Department of Soil Science and Agricultural Chemistry
Tamil Nadu Agricultural University, Coimbatore – 641003, India
*Corresponding Author E-mail: chithuragul@gmail.com
Received: 15.03.2020  |  Revised: 23.04.2020   |  Accepted: 27.04.2020 

 ABSTRACT

A study was taken up to understand the heterotic potential of sweet corn hybrids in terms of green cob yield. The crosses were made in line x tester fashion with seven lines and testers each. The resulting 49 hybrids were evaluated against the popular private hybrid Sugar 75.  Highly significant variance due to genotypes was obtained for all the characters, which indicated the presence of sufficient variability for improvement. The lines L5 and L4  and the testers T6 and T5 were identified as desirable parents for developing hybrids with improved yield and quality traits due to high  per se performance.   The hybrids  L4 xT6  , L4 xT5, L5xT6, L1 xT7, and L7 xT3  exhibited higher  mean performance for green cob yield. which The hybrid L4 xT6 showed favourable per se performances for thirteen traits in addition to green cob yield. The best five hybrids identified based on mean performance for green cob yield and its associated traits were L4 xT6 , L4 xT5, L5xT6, L1 xT7, and L7 xT3   and these hybrids possess atleast one of the parents which were found to be having superiority in mean performance. For total sugar content trait, hybrids L6 xT5, L5 xT7, L1 xT3 and L5 xT6 showed significant positive heterosis.These hybrids can be potentially used after testing their performance over locations.

Keywords: Sweet Corn, Hybrids, Heterotic potential, Green cob yield.

Full Text : PDF; Journal doi : http://dx.doi.org/10.18782

Cite this article: Ravikesavan, R., Niji, M.S., Ganesan, K.N., & Chitdeshwari, T. (2020). Heterotic Potential for Green Cob Yield and Related Traits in Sweet Corn   (Zea mays L. saccharata), Ind. J. Pure App. Biosci. 8(2), 303-310. doi: http://dx.doi.org/10.18782/2582-2845.8061

INTRODUCTION

Sweet corn (Zea mays L. saccharata) is also called as pole corn and sugar corn is one of the special types of normal corn (Zea mays L.) with high sugar content. It is a popular fresh vegetable in countries like USA and Canada. This specialty corn is characterized by sweet taste, thin pericarp, delicate textured endosperm and high nutritional value. The matured kernels are having translucent, horny appearance and become wrinkled when it dries (Sutharet al., 2014).
Sweet corn is harvested in the milk stage and is used for human consumption in fresh form or in processed foods. The research reports indicate that in the 19th century, sweet corn has arisen as a result of natural recessive mutation in the genes controlling sugar to starch conversion inside the corn kernels. Total sugar content in sweet corn at milky stage ranges from 20-30% as compared to 2-5% of normal corn. In the sweet corn genome at least one of the eight genes involved in the endosperm carbohydrate biosynthesis is in recessive mutant condition, which inhibits the sugar to starch conversion. Initially the corn lines with only the sugary (su) allele on chromosome 4 used to be referred to as sweet corn. This standard sugary (su) corn is thought to have originated from a Peruvian race Chullpi via natural mutation. Currently,  several endosperm genes affect carbohydrate synthesis are being used either singly or in combination for the development of sweet corn varieties. These genes includes sugary (su), sugary enhancer (se), shrunken-2 (sh2), brittle (bt), brittle-2 (bt2), Amylose Extender (ae), “Dull” (du) and Waxy (wx) (Tracyet al., 2006).
Sweet corn is having high quality phyto-nutrition profile. It is one of the richest sources of dietary fiber, vitamin A, B complex vitamins such as thiamin, niacin, pantothenic acid, folates, riboflavin, pyridoxine and flavonoid antioxidant ferulic acid. It contains healthy amounts of essential minerals like iron (Fe), zinc (Zn), magnesium (Mg), copper (Cu), and manganese (Mn).
Sweet corn breeding programme was started early and several composites like Madhuri (1990), Priya (2002) were developed and released for general cultivation of farmers. Even though the composites are having high quality, their yield potential is low as compared to the hybrids. They produce small sized cobs, which reduces their market value. Among the hybrids, single cross hybrids are more advantageous than double and three way cross hybrids due to the uniformity in different agronomic traits as well as their simpler and faster breeding procedure. Heterosis breeding objectives in sweet corn depends on the market requirements, however the most important objective is to increase green cob yield and quality. Quality of sweet corn is measured in terms of higher sugar content, water soluble polysaccharides, shelf life, texture, cob size, cob length, flavor etc. This study was taken up in order to identify superior hybrids with high sugar content for commercial exploitation

MATERIALS AND METHODS

The experimental material comprised of 14 parents (7 Lines and 7 Testers) and 49 crosses derived from them along with a check (Sugar 75). Genetically pure seed materials of 14 inbred parents obtained from the Department of Millets, CPBG, TNAU, Coimbatore formed the base for the present study. List of parental lines and testers are given in Table1.
The seven inbred lines were crossed with seven testers in Line x Tester (L x T) mating design to generate 49 crosses.  For crossing, hand emasculation and pollination method was followed. The tassels of the female plants (lines) were removed immediately as soon as appeared (detasseling). The ear shoot emerging from the leaf sheath was bagged using butter paper cover to avoid pollen contamination. The tassels of male plants (testers) were also covered with brown paper cover before anthesis and two days prior to the silk emergence in the morning 9.00 – 10.00A.M in order to collect the pollen grains. Hand pollination was done during 9-11 A.M. After carefully removing the butter paper cover, pollens from the tassel bag were dusted over the silk and the cover was replaced immediately after dusting and covered to avoid contamination from other pollen sources.
The newly synthesized forty nine hybrids along with the fourteen parents were evaluated along with standard check, Sugar 75. Each hybrid/ parent was raised in two rows each of 4m length in RBD. The recommended package of practices was followed and biometrical observations were recorded on five randomly selected plants for 17 quantitative traits and three qualitative traits.  In both parents and F1s, five plants from each genotype in every replication were selected and tagged randomly for recording the biometrical observations. Eighteen yield and yield contributing characters, one physiological parameter and five quality traits were recorded. The average values obtained from the five representative plants are considered as the mean value of that genotype in each replication. These mean values were used for statistical analysis.
The overall mean value for each parent and hybrid for each character was taken for estimation of heterosis. The magnitude of heterosis in hybrids was expressed as percentage increase or decrease of a character over mid parent (di), better parent (dii) and standard check (diii) and was estimated using the following formula (Turner, 1953 )

RESULTS AND DISCUSSION

Highly significant variance due to genotypes was obtained for all the characters, which indicated the presence of sufficient variability for improvement. Variance due to parents and hybrids were significant for most of the traits except days to silking (parents) and tassel branches (hybrids). The significant difference among the genotypes for all the twenty five characters were tested by analysing the different components of variance. The results revealed that variation due to genotypes were found to be significant for all the characters studied, which indicated the presence sufficient variability among the genotypes for improvement. Similar results were reported by Kumara et al. (2013) for plant height, days to 50% tasseling, days to 50% silking, cob length, cob breadth, number of kernel rows per cob, number of kernels per row, green cob yield, total soluble solids, total sugar, reducing sugar and non-reducing sugar. Other sources of variation viz., parents ,crosses and parent vs crosses showed significance for most of the characters except days to silking (parents), tassel branches (crosses), days to tasseling, days to 50% tasseling and total soluble solids (parent vs crosses).
Information on the magnitude of  heterosis is a pre- requisite in the development of hybrids. A good hybrid should manifest high amount of heterosis for commercial exploitation. Kabdal et al. (2003) reported that more reliable results were produced when best crosses were selected based on heterosis along with per se performance for grain yield and cob length. For flowering traits like days to 50% tasseling and days to 50% silking, heterosis in the negative direction is considered as desirable (Kumaret al., 2014).
The hybrids  L4 xT6  , L4 xT5, L5xT6, L1 xT7, and L7 xT3  exhibited higher  mean performance for green cob yield, in which L4 xT6 hybrid showed favourable per se performances for thirteen traits in addition to green cob yield viz., days to 50% silking, tassel length, cob placement height, green cob weight, cob length, cob breadth, number of kernel rows per cob, number of kernels per row, dry cob weight, seed weight per cob, hundred seed weight, total chlorophyll content and zinc content. This was followed by L5xT6, which exhibited desirable mean performance for ten other characters also. The next best hybrid, L4 xT5 exhibited significant mean performance for eight more characters besides yield which includes, days to 50% silking, green cob weight,  cob length, dry cob weight, seed weight per cob, total chlorophyll content, total sugar and iron content. Following this, L1 xT7 was found to be good with significant per se performance for days to 50% tasseling, days to 50% silking, green cob weight, cob length, number of kernel rows per cob, total sugar and zinc content. The hybrid L7 xT3   exhibited desirable mean performances for a total of six characters under study.           
According to Suhasini et al. (2016), green cob yield has positive and significant correlation with with number of kernel rows per cob, plant height, green cob weight, cob length, cob breadth, 100 seed weight, number of kernels per row indicating that indirect selection for yield through these traits will be effective.
            The best five hybrids identified based on mean performance for green cob yield and yield contributing traits were L4 xT6 , L4 xT5, L5xT6, L1 xT7, and L7 xT3   and these hybrids possess atleast one of the parents which were found to be having superiority in mean performance. Hence, from the present study it was evident that parents with good per se performance can result in good hybrids.
In the present study, three hybrids recorded significant positive standard heterosis over the check Sugar 75 for green cob  yield viz.,L4 xT6 , L5  x T6 and  L4 xT5.  Besides yield, L4 xT6 showed significant heterosis for cob length, green cob weight, cob placement height, tassel length, days to 50%  silking, number of kernel rows per cob, number of kernels per row, dry cob weight, seed weight per cob, 100 seed weight, total chlorophyll content and zinc content.  Green cob weight had positive and significant relationship with cob length  followed by number of kernels per row and  cob breadth  in the studies by Chinthiya et al. (2019), and  in the present study also heterotic hybrids were identified  with  better green cob yield  combined with yield attributing traits.  Hybrids L5xT6  and L4 xT5 recorded significant economic heterosis superiority for a total of seven traits. For total sugar content trait, hybrids L6 xT5, L5 xT7, L1 xT3 and L5 xT6 showed significant positive heterosis.
Hence, the hybrids L4 xT6 , L5xT6and L4 xT5 were identified as superior based on significant standard heterosis over the check Sugar 75 for yield and contributing traits. For total sugar, hybrids L6 xT5, L5 xT7, L1 xT3 and L5 xT6 were found to be superior. Similar results for economic heterosis were reported by Kabdalet al. (2003) for grain yield and cob length,   Kumar et al. (2014) for days to 50% tasseling, cob placement height, cob length, cob breadth, 100 seed weight and grain yield. Sadaiahetal. (2013) reported same findings for total sugar. Similar results for most of the traits such as green cob yield., tassel branches, cob length, cob breadth, number of kernels per row, dry cob yield, seed weight per cob and 100 seed weight were reported by Suhasini (2016).

Table 1: List of lines and testers used

Sl.No

Code No.

Name of the lines/Testers

1

L1

WNC 12069

2

L2

SC1107

3

L3

USC 1-2-3-1

4

L4

SC 11-2

5

L5

12039-1

6

L6

1421-5-2-1

7

L7

12068-2

8

T1

MRCSC 13

9

T2

MRCSC 2

10

T3

WNDMRSCY 19 R 773

11

T4

DMSC 24

12

T5

DMSC 20

13

T6

951-7

14

T7

DMSC 36

Table 2: Mean squares analysis of variances

Characters

Sources of variation

 

Genotypes

Hybrids

Parents

Parents vs
hybrids

Error

 

 

 

Days to tasseling

9.29**

10.23**

6.40**

1.96

1.56

 

Days to silking

4.16**

4.61**

1.66

14.97**

1.74

 

Days to 50% tasseling

15.28**

14.15**

20.04**

7.20

2.14

 

Days to 50% silking

7.77**

5.38**

10.55**

86.35**

2.05

 

ASI

5.73**

4.31**

10.96**

6.10**

0.21

 

Plant height

458.27**

327.97**

145.97**

10772.43**

37.62

 

Tassel length

27.93**

13.13**

26.98**

750.83**

3.40

 

Tassel branches

5.20**

3.75

9.48**

18.98*

2.85

 

Cob placement height

241.98**

211.22**

191.93**

2369.05**

22.51

 

Green cob yield

14.81**

3.93**

3.65**

681.14**

0.27

 

Green cob weight

1705.41**

810.29**

1151.25**

51875.94**

61.40

 

Cob length

4.35**

2.96**

5.39**

57.48**

0.17

 

Cob breadth

1.25**

0.75**

0.95**

29.02**

0.27

 

Number of kernel rows per cob

4.93**

5.00**

4.47**

7.91**

0.89

 

Number of kernels per row

38.72**

36.88**

46.56**

25.55**

1.42

 

Dry cob weight

186.95**

167.88**

54.99**

2817.29**

7.40

 

Seed weight per cob

150.08**

133.81**

117.77**

1351.00**

9.37

 

100 seed weight

10.35**

9.61**

11.41**

32.09**

0.98

 

Total sugar

31.55**

31.64**

32.48**

14.96**

0.90

 

Reducing sugar

0.48**

0.50**

0.40**

0.89**

0.01

 

Non reducing sugar

37.30**

37.13**

39.02**

23.20**

0.93

 

Total soluble solids

2.73**

2.36**

4.30**

0.01

0.13

 

Total chlorophyll content

28.53**

20.39**

30.39**

395.24**

6.56

 

Fe content

22.27**

12.82**

11.53**

615.84**

0.09

 

Zn content

5.89**

5.43**

2.28**

75.06**

0.03

 

*significant at 5% level                                        **significant at 1% level.

Table  3: Standard  heterosis (diii) exhibited by the sweet corn hybrids for  various traits

S.No

Hybrids

Days to 50% tasseling

Days to 50% silking

ASI

Cob placement height

Single Green cob weight

Cob length

Cob Breadth

No.of kernel rows per cob

No.of kernels per row

Green cob yield

Total sugar

1

L1 x T1

8.16 **

3.85 ns

-75.00 **

3.15 ns

-12.33

-11.82**

-2.50 ns

-10.60 *

-8.00 **

-20.81 **

-5.68 ns

2

L1 x T2

4.08 ns

1.92 ns

-50.00 **

6.54 ns

-7.26

5.31 **

1.93 ns

8.06 ns

-3.20 *

-12.52 **

-19.05 **

3

L1 x T3

0.00 ns

0.00 ns

-16.67 ns

3.68 ns

11.54 **

-10.10**

-1.40 ns

-7.83 ns

-9.60 **

-11.30 **

10.62 *

4

L1 x T4

-4.08 ns

-3.85 ns

0.00 ns

8.79 ns

-12.30

0.51 ns

-0.29 ns

5.53 ns

-20.0 **

-4.85 ns

-26.11 **

5

L1 x T5

-2.04 ns

-1.92 ns

-25.00 *

19.82 **

-5.89 ns

5.31 **

2.15 ns

5.76 ns

-13.60 **

-10.37 *

-8.95 ns

6

L1 x T6

-1.36 ns

0.00 ns

-50.00 **

23.01 **

-4.06 ns

-3.60 *

3.92 ns

-7.14 ns

-14.40 **

-17.13 **

-17.13 **

7

L1 x T7

-4.08 ns

-3.85 ns

16.67 ns

12.91 **

17.26 **

5.65 **

4.14 ns

13.36 *

-23.20 **

4.36 ns

5.98 ns

8

L2 x T1

-4.76 ns

-4.49 *

-25.00 *

12.26 *

-10.13

-6.34 **

1.26 ns

-5.53 ns

-14.40 **

-20.20 **

-8.45 ns

9

L2 x T2

2.04 ns

1.92 ns

-75.00 **

-0.37 ns

-5.87 ns

-3.94 *

2.37 ns

-1.15 ns

-16.80 **

-20.20 **

-28.35 **

10

L2 x T3

0.00 ns

-3.85 ns

0.00 ns

14.96 **

-2.77 ns

-1.37 ns

0.16 ns

2.30 ns

-9.60 **

3.13 ns

6.45 ns

11

L2 x T4

-1.36 ns

-2.56 ns

-33.33 **

23.13 **

-2.58 ns

0.68 ns

0.38 ns

-21.89 **

-6.40 **

-18.05 **

2.97 ns

12

L2 x T5

-2.04 ns

-1.92 ns

-16.67 ns

22.72 **

0.07 ns

1.20 ns

1.71 ns

-6.22 ns

-13.60 **

4.97 ns

11.82 **

13

L2 x T6

8.16 **

3.85 ns

-50.00 **

19.08 **

-16.23

-1.71 ns

3.70 ns

4.15 ns

-20.80 **

-18.97 **

-19.64 **

14

L2 x T7

-4.08 ns

0.00 ns

25.00 *

25.05 **

-2.87 ns

3.25 ns

4.14 ns

6.91 ns

-23.20 **

3.44 ns

18.93 **

15

L3 x T1

4.08 ns

-1.92 ns

-25.00 *

32.37 **

9.73 **

-0.68 ns

-6.27 *

-12.21 *

-12.80 **

-9.15 *

-3.91 ns

16

L3 x T2

0.00 ns

-3.85 ns

0.00 ns

32.24 **

8.68 **

-2.40 ns

1.04 ns

5.76 ns

-25.60 **

-8.53 *

-16.38 **

17

L3 x T3

-6.12 *

0.00 ns

25.00 *

26.28 **

3.16 ns

-7.02 **

1.04 ns

0.69 ns

-11.20 **

-35.54 **

1.57 ns

18

L3 x T4

4.08 ns

1.92 ns

-50.00 **

44.83 **

-10.41

-5.99 **

4.37 ns

5.30 ns

-4.80 **

-16.82 **

8.83 ns

19

L3 x T5

-0.68 ns

-0.64 ns

-8.33 ns

30.12 **

8.58 **

5.82 **

5.03 ns

9.68 ns

-16.00 **

-3.62 ns

5.98 ns

20

L3 x T6

0.00 ns

-1.92 ns

-25.00 *

35.55 **

8.36 **

2.74 ns

1.48 ns

15.67 **

-8.80 **

-9.15 *

9.06 *

21

L3 x T7

-2.04 ns

0.00 ns

25.00 *

17.86 **

5.58 ns

-5.82 **

-0.95 ns

-3.00 ns

-25.60 **

-4.24 ns

-55.21 **

22

L4 x T1

-4.08 ns

-1.92 ns

50.00 **

29.71 **

8.79 **

-2.40 ns

3.04 ns

-12.21 *

-11.20 **

-10.07 *

-36.71 **

23

L4 x T2

6.12 *

1.92 ns

-50.00 **

20.31 **

-1.20 ns

1.20 ns

0.60 ns

3.46 ns

-25.60 **

-19.28 **

-16.34 **

24

L4 x T3

10.20 **

1.92 ns

-75.00 **

23.42 **

2.09 ns

4.79 **

3.26 ns

2.07 ns

-14.40 **

-22.65 **

-1.85 ns

25

L4 x T4

-6.12 *

-3.85 ns

25.00 *

14.75 **

-1.63 ns

-0.17 ns

-2.28 ns

-12.44 *

-36.80 **

1.29 ns

-2.97 ns

26

L4 x T5

-3.40 ns

-4.49 *

0.00 ns

29.26 **

10.23 **

5.82 **

5.92 *

0.92 ns

-10.40 **

8.35 *

13.08 **

27

L4 x T6

-3.40 ns

-4.49 *

-25.00 *

38.17 **

15.01 **

7.88 **

7.25 *

10.60 *

3.20 *

19.09 **

-16.38 **

28

L4 x T7

2.04 ns

0.00 ns

-25.00 *

25.01 **

0.82 ns

-5.14 **

4.14 ns

13.82 **

-3.20 *

-11.60 **

5.43 ns

29

L5 x T1

-4.08 ns

-3.85 ns

-16.67 ns

18.51 **

-2.04 ns

-0.34 ns

5.25 ns

7.14 ns

-14.40 **

-3.93 ns

-26.52 **

30

L5 x T2

-0.68 ns

-1.92 ns

8.33 ns

2.00 ns

9.63 **

-10.10 **

-5.61 *

-13.59 *

1.60 ns

-16.82 **

-19.66 **

31

L5 x T3

0.00 ns

0.00 ns

-25.00 *

25.30 **

-1.29 ns

-1.37 ns

-0.73 ns

2.76 ns

-7.20 **

-11.60 **

-34.94 **

32

L5 x T4

4.08 ns

-1.92 ns

-25.00 *

20.15 **

2.09 ns

4.11 *

-0.95 ns

1.61 ns

-10.40 **

-7.92 ns

-11.88 **

33

L5 x T5

-4.08 ns

-3.85 ns

-25.00 *

15.53 **

-0.91 ns

-4.45 *

8.35 **

-1.38 ns

-20.80 **

-7.31 ns

-5.27 ns

34

L5 x T6

-6.12 *

-3.85 ns

-50.00 **

34.70 **

-2.87 ns

8.90 **

11.01 **

2.07 ns

-2.40 ns

9.27 *

10.15 *

35

L5 x T7

2.04 ns

0.00 ns

-50.00 **

22.68 **

-2.81 ns

-0.86 ns

3.70 ns

-12.44 *

-8.80 **

-13.44 **

25.32**

36

L6 x T1

2.04 ns

-1.92 ns

-25.00 *

24.93 **

-11.81**

-1.88 ns

7.02 *

-5.99 ns

-16.00 **

-10.99 **

6.17 ns

37

L6 x T2

-4.08 ns

-1.92 ns

0.00 ns

12.67 **

-7.86 **

-5.65 **

4.59 ns

8.99 ns

-4.00 *

-8.23 *

-39.26 **

38

L6 x T3

-2.04 ns

-3.85 ns

0.00 ns

30.20 **

-6.83*

8.90 **

1.93 ns

4.84 ns

-6.40 **

-5.46 ns

-12.82 **

39

L6 x T4

10.20 **

3.85 ns

-75.00 **

31.71 **

-1.15 ns

-4.62 **

-1.62 ns

9.91 ns

-31.20 **

-34.32 **

-30.06 **

40

L6 x T5

2.04 ns

0.00 ns

-25.00 *

31.47 **

-10.20**

-0.86 ns

2.37 ns

9.22 ns

-16.00 **

-10.68 **

27.29 **

41

L6 x T6

0.00 ns

-3.85 ns

0.00 ns

31.02 **

-6.40*

-3.42 *

1.71 ns

-9.22 ns

-20.00 **

-3.93 ns

24.93 **

42

L6 x T7

4.08 ns

-1.92 ns

-25.00 *

32.57 **

-5.11 ns

-0.17 ns

0.16 ns

6.68 ns

-5.60 **

-9.15 *

-12.90 **

43

L7 x T1

-3.40 ns

-2.56 ns

-25.00 *

24.07 **

13.03 **

1.20 ns

-0.51 ns

8.53 ns

-24.80 **

-8.84 *

-43.41 **

44

L7 x T2

4.08 ns

1.92 ns

-25.00 *

17.57 **

5.72 ns

-7.19 **

-0.73 ns

5.99 ns

-7.20 **

-9.45 *

-7.18 ns

45

L7 x T3

10.20 **

3.85 ns

-75.00 **

5.44 ns

-3.55 ns

-4.45 *

1.71 ns

11.52 *

-16.00 **

4.36 ns

-16.71 **

46

L7 x T4

-0.68 ns

-1.28 ns

-33.33 **

16.76 **

-6.59*

-5.99 **

4.81 ns

-0.23 ns

-8.80 **

-12.83 **

12.86 **

47

L7 x T5

0.00 ns

0.00 ns

-33.33 **

10.22 *

-5.11 ns

-2.23 ns

3.70 ns

-11.75 *

-22.40 **

-19.89 **

-3.79 ns

48

L7 x T6

-0.68 ns

3.85 ns

-8.33 ns

15.41 **

-2.60 ns

-8.05 **

-0.29 ns

-14.52 **

-20.80 **

-1.47 ns

-13.76 **

49

L7 x T7

6.12 *

1.92 ns

-75.00 **

10.30 *

-1.29 ns

4.79 **

6.14 *

-6.45 ns

-18.40 **

-22.34 **

-42.37 **

Range

-6.12 to10.20

-4.49 to 3.85

-75 to 50

-0.04 to 44.83

-16.23 to17.26

-11.82   to7.88

-6.27 to 11.01

-21.89 to 15.67

-36.80 to 3.2

-35.54 to 19.09

-55.21 to27.29

Table 5: Best hybrids for important traits based on mean performance and standard heterosis

Sl.No.

Characters

Mean

Standard heterosis

Mean and standard heterosis

1

Days to 50% tasseling

L3 x T3 , L4 x T4 , L5 x T6 , L2  x T1 , L1 x T4 , L1 x T7 , L2 x T7 , L6 x T2 , L7 x T1 , L7 x T4

L3 x T3 , L4 x T4 , L5 x T6

L3 x T3 , L4 x T4 , L5 x T6

2

Days to 50% silking

L2 x T1 , L4 x T5 , L4 x T6 , L1x T4 , L1 x T7 , L2 x T3 , L3 xT2 , L4 x T4 , L4 x T6 , L5 x T1, L5 x T5 , L5 x T6 , L6 x T3 ,L6 x T6

L2 x T1 , L4 x T5 , L4 x T6

L4 x T6

3

Anthesis Silking Interval

L1 x T1 , L2 x T2 , L1 x T6 , L4x T3 , L6 x T4 , L7 x T3

L3 x T4 , L5 x T7, L1 x T1 , L2x T2 , L5 x T6 , L4 x T3 , L6 xT4 , L7 x T3

 L1 x T1 ,L2 x T2 , L4 x T3 , L6 x T4 ,L7 x T3

4

Tassel length

L1 x T3 , L7 x T6 , L5 x T7 ,L4 x T6

L1 x T3 , L1 x T5 , L4 x T6, L5x T7 , L7 x T6

L1 x T3 ,  L5 x T7 ,
L7 x T6, L4 x T6

5

Tassel branches

L1 x T6

L1 x T6

L1 x T6

6

Cob placement height

L3 x T4 , L3 x T6 , L4 x T6 ,L5 x T6 , L3 x T1 , L3 x T2 ,L6 x T4

L3 x T4 , L3 x T6 , L4 x T6, L5x T6 , L6 x T7

L3 x T4 , L3 x T6 , L4 x T6,

7

Green cob weight

L1 x T7 , L4 x T6 , L7 x T1 , L1x T3 , L4 x T5

L1 x T3 , L1 x T7 , L4 x T5 ,
L4 x T6 , L7 x T1

L1 x T3 , L1 x T7 , L4 x T6 ,
L4 x T5 , L7 x T1

8

Cob length

L5 x T6 , L6 x T3 , L4 x T6 ,L3 x T5 , L4 x T5 , L1 x T7 ,L2 x T7

L1 x T7 , L3 x T5 , L4 x T5 ,
L4 x T6 , L5 x T6 , L6 x T3

L1 x T7 , L3 x T5 , L4 x T5 ,
L4 x T6 , L5 x T6 , L6 x T3

9

Cob breadth

L5 x T6 , L5 x T5 , L4 x T4

L4 x T5 , L4 x T6 , L5 x T5 ,
L5 x T6 , L7 x T7

L5 x T6 , L5 x T5 , L4 x T4

10

Number of kernel rows per cob

L3 x T6 , L4 x T6 , L1 x T7 ,L7 x T3 , L4 x T6

L1 x T7 , L3 x T6 , L4 x T6 , L4 x T7 , L7 x T3

L1 x T7 , L3 x T6 , L4 x T6 , L4 x T7 , L7 x T3

11

Number of kernels per  Row

L4 x T6 , L5 x T2 , L5 x T6 ,L1 x T2 , L4 xT7

L4 x T6

L4 x T6

12

Green cob yield

L1 x T7, L2 x T3, L2 x T5 , L2x T7 , L4 x T4  L4 x T5 , L4 xT6 , L5 x T6 , L7 x T3 , L7 x T6

L4 x T5 , L4 x T6 , L5 x T6

L4 x T5 , L4 x T6 , L5 x T6

13

Dry cob weight

L5 x T6 , L4 x T5 , L7 x T3 ,
L2 x T5 , L4 x T6, L4 x T4

L2 x T5 , L4 x T6 , L5 x T6 ,
L7 x T3

L2 x T5 , L4 x T6 , L5 x T6 ,
L7 x T3

14

Seed weight per cob

L4 x T6 , L7 x T3 , L2 x T5 ,L5 x T6 , L4 x T4, L4 x T5

L2 x T5 , L4 x T4 , L4 x T6 ,
L5 x T6 , L7 x T3

L2 x T5 , L4 x T4 , L4 x T6 ,
L5 x T6 , L7 x T3

15

Hundred seed weight

L7 x T5, L1 x T5, L6 x T5 ,L2 x T5 ,
L4 x T6, L5 x T6 ,L7 x T3

L1 x T5, L2 x T5 , L4 x T6 ,
L6 x T5 , L7 x T3, L7 x T5

L1 x T5, L2 x T5 , L4 x T6 ,
L6 x T5 , L7 x T3, L7 x T5

16

Total chlorophyll
Content

L4 x T5, L4 x T6, L1 x T4 ,
L6 x T2 , L7 x T5

L4 x T5, L4 x T6, L1 x T4 ,
L6 x T2 , L7 x T5

L4 x T5, L4 x T6, L1 x T4 ,
L6 x T2 , L7 x T5

17

Total sugar

L6 x T5, L5 x T7, L4 x T5 ,L5 x T6 , L6 x T6 , L2 x T7 ,L1 x T3 , L2 x T3 , L2 x T4 ,L2x T5, L1 x T7

L5 x T6, L5 x T7, L2 x T7 ,
L6 x T5 , L6 x T6 , L3 x T6 ,L2 x T5 , L1 x T3

L5 x T6, L5 x T7, L2 x T7 ,
L6 x T5 , L6 x T6 ,L2 x T5 , L1 x T3

18

Fe content

L1 x T1, L1 x T3 , L1 x T5,L1 x T6 , L4 x T5 , L7 x T2 ,L7 x T7

L7 x T7 , L7 x T2 , L4 x T5

L7 x T7 , L7 x T2 , L4 x T5

19

Zn content

L1 x T2, L1 x T3 , L1 x T5,L4 x T6 ,  L1 x T7 ,  L2 x T5 ,L1 x T7

L4 x T6, L1 x T2 , L1 x T3,
L1 x T5

L4 x T6, L1 x T2 , L1 x T3,
L1 x T5

CONCLUSIONS

The hybrids L4 xT6, L5xT6 and L4 xT5 were identified as superior based on significant standard heterosis over the check Sugar 75 for yield and contributing traits. For total sugar , hybrids L6 xT5, L5 xT7, L1 xT3 and L5 xT6 were found to be superior.

REFERENCES

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Kabdal, M., Verma, S., Kumar, A., & Panwar, U. (2003). Combining ability and heterosis analysis for grain yield and its components in maize (Zea mays L.). Indian Journal of Agricultural Research, 37(1), 39-43.
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Suhaisini, B., Ravikesavan, R., & Yuaraja, A. (2016). Genetic Variability and Correlation among Yield and Yield Contributing Traits in Sweet Corn. Madras Agricultural Journal, 103, 293-296
Suthar, M., Singh, D., Nepalia, V., & Singh, A. (2014). Performance of sweet corn (Zea mays) varieties under varying fertility levels. Indian Journal of Agronomy, 59(1), 168-170.
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Turner, J.H. (1953). A study of heterosis in upland cotton II, Combining ability and inbreeding effects. Agron. J., 45, 487-493.




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