1. TITLE: Identification of Potential Combiners Through Reciprocal

2. Selection in Segregating Generations of Cotton

3. (Gossypium hirsutum L.)

6. DESCIPLINE: Breeding and Genetics

8. AUTHORS: Dr.Somashekhar (Corresponding Author)

9. Research Associate

10. ARS,Dharwad Farm –Dharwad-580 007

11. Phone-0836-2447874

12. E-mail-somuvd@rediffmail.com

14. Dr.S.A.Patil

15. Director, IARI,

16. New Delhi

18. Dr.S.S.Patil

19. Principal Scientist,and Head

20. ARS,Dharwad Farm –Dharwad-580 007

22. Dr.Rajesh .Patil

23. Asst.proffessor(GPB)

24. ARS,Dharwad Farm –Dharwad-580 007

Abstract: TwoF₁ hybrids (RAHH-102 and RAHH-136), which are distinct, were identified through their predicted double cross performance as potential sources of inbred lines for hybrid cotton cultivars. F₄ lines were derived from these crosses and utilized in a study on variability for combining ability. Sets of 26 lines each from the two crosses were crossed in a reciprocal fashion to the F₁ parent as a tester for combining ability. The improvements in performance of F₁ hybrids derived by crossing the best performing F₄ lines as predicted by their reciprocal test cross performance indicated that progress could be made for gain in combining ability through a breeding procedure similar to reciprocal recurrent selection in cross pollinated crops.

Introduction

Cotton improvement programmes that concentrate on the development of hybrids have contributed to improving cotton productivity (Dagaonkar and Malkandale,1993). However, genetic gain in yield potential of hybrids appears to be approaching stagnation. In breeding programmes aimed at improving productivity of pure lines, i.e., not hybrids, variability is created and exploited by practicing selecting for yield during segregating generations. However, improving the performance of hybrids requires that scientists consider the combining ability of potential parental material (Patil and Patil, 2003). In cross pollinated crops like maize, hybrid breeding programmes are supplemented by regular systematic programmes aimed at improving combining ability (Patil and Pandit, 1991). Systematic attempts have not been practiced in cotton to create variability for combining ability, i.e., combining ability was not considered as a trait for improvement in hybrid breeding programmes. Reciprocal recurrent selection schemes for improving combining ability have been an integral part of hybrid breeding programmes in cross pollinated crops and such programmes have contributed to success of hybrid maize. The procedures of improving combining ability in cross pollinated species can not be followed in cotton without suitable modification. Hence, there is a need for defining procedures of improving combining ability to serve as a pre-requisite in hybrid breeding in cotton. It is possible to recombine two, four or more lines (selected for combining ability) by single, double or multiple crossing or simulated intermating. Generally, individual plants in the F₄ generation are selfed and crossed with a tester line to initiate the selection of improved inbreds. The objective of this research was to determine the combining ability among segregant F₄ lines within two diverse populations.

Material and Methods

Following analysis (data not shown) of a large set of single crosses, two single cross hybrids RAHH 102 (RAH10  RA100) and RAHH 136 (RAH20  RAH200) were selected for this study based on their predicted double cross performance(Patil and Patil, 2003). Plants within each population were advanced to the F₄ generation. Twenty-six, i.e., single plants, from each cross were selected randomly and crossed to the reciprocal F₁ hybrid as the tester parent. Thus, F₄ plants from RAHH 102 were crossed with RAHH 136 F₁ and random F₄ plants from RAHH 136 were crossed to RAHH 102 F₁ to establish two sets of reciprocal hybrids. A field evaluation was conducted for two set of hybrids in Randomized complete block design with three replication having two rows of 5 m length. The whole experiment i.e., Crossing and evaluation of the hybrids, was conducted at Dharwad which receives an annual rainfall of 750 mm. Proper pest and disease control measure was taken to avoid economic loss during 2004-05 for the characterization of the combining ability status of the 26 F₄ lines of each set. This was determined based on the performance of the crosses (seedcotton yield) compared with the F₁ reciprocal testers. Each F₄ line was assigned to one of four classes based on the overall mean of all crosses. These classes were: 1 (greater than (single cross parental mean + 1 sd unit)) , 2 (equal to the (single cross parental mean + 1 sd unit) , 3 (equal to the single cross mean – 1 sd unit) , and 4 (less than (single cross parental mean – 1 sd unit)) as suggested by Patil (1995). Thus, for lines of RAHH 102,, four classes of combining ability status were defined as E1, E2, E3, and E4, respectively. Similarly, F1, F2, F3, and F4 classes were defined representing the decreasing order to superiority of the crosses for the lines of RAHH 136.

Percent improvement in performance of reciprocal test cross hybrids over the mean of the reciprocal hybrid parents was calculated as an estimate of the combining ability of the each population. Hybrids were developed by crossing the best combining inbred lines in all possible combinations in the following season. Performance of these hybrids, F₅ x F₅, were determined with three replications of hybrids in a RBD having three row x 5 m plots during 2006 in the same location . Hybrids were compared with a commercial cultivar, Bunny, and the two original single crosses.

Results and Discussion

Four lines of RAHH 102 lines with F₁ RAHH 136 hybrids exceeded the mean of all of the 26 test cross hybrids by more than one standard deviation unit (Table 1). These were developed from lines R-18 (102), R-25 (102), R-22 (102), and R-26 (102) and yielded 2930, 2804, 2591, and 2582 kg ha^-1, respectively, compared with the mean of all 26 hybrids of 2173 kg ha^-1. Twelve additional lines of RAHH 102 with reciprocal hybrid yielded within one standard deviation above the overall mean while eight hybrids performed within one standard deviation below the mean, and only two R- (102) hybrids yielded more than one standard deviation below the overall mean. The highest yielding hybrid, R-18 (102) x RAHH 136 F₁, produced 49% more seedcotton than the average of two straight crosses, while R-2 (102) x RAHH 136 F₁ yielded 45 % less seedcotton. Four lines of RAHH 136 with RAHH 102 F₁ as a tester produced hybrids that exceeded the mean of two straight crosses by more than one standard deviation unit (Table 2). These were R-2 (136), R-14 (136), R-16 (136), and R-15 (136), which yielded 2817, 2397, 2392, and 2389 kg ha^-1, respectively, compared with the mean of two straight crosses of 1930 kg ha^-1. Seventeen of these 26 hybrids were in the F2 or F3 categories, i.e., within one sd unit of the overall mean, while five hybrids yielded more than one sd below the overall mean. The superior F₄ lines from RAHH 102(four) and from RAHH 136(four) that produced the superior reciprocal hybrids were subsequently crossed to produce all possible F₁ hybrids (Table 3). All hybrids except R-26 (102) x R-15 (136) exceeded (p=0.05) the yield of Bunny, which was not different than the mean yield of RAHH 102 and RAHH 136 in this trial. The numerically highest yielding hybrid was R-25 (102) x R-2 (136) at 3593 kg ha^-1, which was 51% higher than Bunny. In conclusion, in the reciprocal recurrent selection scheme proposed herein for cotton, the elite high combiner plants obtained from the reciprocal populations represent gain obtained from practicing selection for combining ability. We propose that such elite lines of the corresponding population can be intermated to start the next cycle of recurrent selection. In this study, the elite lines per se produced highly productive hybrids, indicating the magnitude of improving combining ability achieved through selection practiced in one cycle of reciprocal selection.

Table 1: Performance of reciprocal crosses derived from the lines RAHH-102 crossed with tester RAHH-136 F₁ during 2004.

F4 line No.	Crosses	Seed cotton yield (kg ha-1)	% Improvement	Ranking
R-18 (102)	R-18 (102) x RAHH 136 F1	2929.89	49.01	E1
R-25 (102)	R-25 (102) x RAHH 136 F1	2803.73	42.59	E1
R-22 (102)	R-22 (102) x RAHH 136 F1	2590.61	31.75	E1
R-26 (102)	R-26 (102) x RAHH 136 F1	2582.01	31.32	E1
R-5 (102)	R-5 (102) x RAHH 136 F1	2488.1	26.54	E2
R-8 (102)	R-8 (102) x RAHH 136 F1	2420.63	23.11	E2
R-11 (102)	R-11 (102) x RAHH 136 F1	2366.4	20.35	E2
R-21 (102)	R-21 (102) x RAHH 136 F1	2355.82	19.81	E2
R-17 (102)	R-17 (102) x RAHH 136 F1	2351.85	19.61	E2
R-7 (102)	R-7 (102) x RAHH 136 F1	2316.14	17.79	E2
R-20 (102)	R-20 (102) x RAHH 136 F1	2314.81	17.73	E2
R-14 (102)	R-14 (102) x RAHH 136 F1	2220.9	12.95	E2
R-15 (102)	R-15 (102) x RAHH 136 F1	2210.98	12.45	E2
R-4 (102)	R-4 (102) x RAHH 136 F1	2191.14	11.44	E2
R-13 (102)	R-13 (102) x RAHH 136 F1	2167.99	10.26	E2
R-9 (102)	R-9 (102) x RAHH 136 F1	2135.58	8.61	E2
R-1 (102)	R-1 (102) x RAHH 136 F1	2115.74	7.60	E3
R-16 (102)	R-16 (102) x RAHH 136 F1	2030.42	3.26	E3
R-10 (102)	R-10 (102) x RAHH 136 F1	2021.83	2.83	E3
R-12 (102)	R-12 (102) x RAHH 136 F1	2005.29	1.98	E3
R-23 (102)	R-23 (102) x RAHH 136 F1	1917.99	-2.46	E3
R-19 (102)	R-19 (102) x RAHH 136 F1	1903.44	-3.20	E3
R-3 (102)	R-3 (102) x RAHH 136 F1	1883.6	-4.20	E3
R-6 (102)	R-6 (102) x RAHH 136 F1	1832.01	-6.83	E3
R-24 (102)	R-24 (102) x RAHH 136 F1	1256.61	-36.09	E4
R-2 (102)	R-2 (102) x RAHH 136 F1	1086.64	-44.74	E4
Mean		2173.083
Standard deviation (sd)		402.6988
Single cross parents
	RAHH102	2140.21
	RAHH 136	1792.33
Mean of single crosses		1966.27

Table 2: Performance of reciprocal crosses derived from the lines of RAHH-136 crossed with tester RAHH-102 (F₁) during 2004.

F4 line No..	Crosses	Seed cotton yield (kg ha-1)	% Improvement	Ranking
R-2(136)	R-2(136) x RAHH 102 F1	2817.46	45.96	F1
R-14(136)	R-14(136) x RAHH 102 F1	2396.83	24.17	F1
R-16(136)	R-16(136) x RAHH 102 F1	2391.53	23.90	F1
R-15(136)	R-15(136) x RAHH 102 F1	2388.89	23.76	F1
R-21(136)	R-21(136) x RAHH 102 F1	2294.31	18.86	F2
R-20(136)	R-20(136) x RAHH 102 F1	2246.03	16.36	F2
R-12(136)	R-12(136) x RAHH 102 F1	2240.08	16.05	F2
R-11(136)	R-11(136) x RAHH 102 F1	2236.77	15.88	F2
R-5(136)	R-5(136) x RAHH 102 F1	2206.35	14.30	F2
R-19(136)	R-19(136) x RAHH 102 F1	2200.53	14.00	F2
R-23(136)	R-23(136) x RAHH 102 F1	2170.63	12.45	F2
R-6(136)	R-6(136) x RAHH 102 F1	2132.94	10.50	F2
R-1(136)	R-1(136) x RAHH 102 F1	2095.24	8.55	F2
R-8(136)	R-8(136) x RAHH 102 F1	2076.72	7.59	F2
R-3(136)	R-3(136) x RAHH 102 F1	2035.05	5.43	F2
R-17(136)	R-17(136) x RAHH 102 F1	1964.29	1.76	F3
R-18(136)	R-18(136) x RAHH 102 F1	1941.8	0.60	F3
R-7(136)	R-7(136) x RAHH 102 F1	1906.75	-1.22	F3
R-10(136)	R-10(136) x RAHH 102 F1	1851.85	-4.06	F3
R-9(136)	R-9(136) x RAHH 102 F1	1780.42	-7.76	F3
R-26(136)	R-26(136) x RAHH 102 F1	1710.32	-11.39	F3
R-13(136)	R-13(136) x RAHH 102 F1	1583.33	-17.97	F4
R-24(136)	R-24(136) x RAHH 102 F1	1539.68	-20.23	F4
R-4(136)	R-4(136) x RAHH 102 F1	1536.38	-20.41	F4
R-22(136)	R-22(136) x RAHH 102 F1	1414.02	-26.74	F4
R-25(136)	R-25(136) x RAHH 102 F1	1148.38	-40.51	F4
Mean		2011.792
Standard deviation (sd)		367.1382
Single cross parents
	RAHH136	2110.21
	RAHH 102	1750.33
Mean of single cross parents		1930.27

Table 3:Performance of elite crosses involving best combiners extracted from opposite population

SL No	Pedigrees of F1 hybrids from superior F4 lines	Seed cotton yield (kg ha-1)	% Improvement over single cross parents	% Improvement over commercial check
1	R-25 (102) x R-2(136)	3592.7	56.2	51.0
2	R-18 (102) x R-2(136)	3412.9	48.4	43.5
3	R-22 (102) x R-2(136)	3225.7	40.2	35.6
4	R-25 (102) x R-14(136)	3183.4	38.4	33.8
5	R-25 (102) x R-16(136)	3076.4	33.8	29.3
6	R-26 (102) x R-14(136)	3051.5	32.7	28.3
7	R-18 (102) x R-14(136)	3047.3	32.5	28.1
8	R-26 (102) x R-2(136)	3027.3	31.6	27.3
9	R-22 (102) x R-14(136)	2994.7	30.2	25.9
10	R-25 (102) x R-15(136)	2945.8	28.1	23.8
11	R-26 (102) x R-16(136)	2944.7	28.0	23.8
12	R-22 (102) x R-16(136)	2896.4	25.9	21.8
13	R-18 (102) x R-16(136)	2865.2	24.6	20.4
14	R-22 (102) x R-15(136)	2856.6	24.2	20.1
15	R-18 (102) x R-15(136)	2756.9	19.9	15.9
16	R-26 (102) x R-15(136)	2692.7	17.1	13.2
MEAN		3035.6	32.0	27.6
Bunny		2378.9
Mean of single cross parents		2300.0
	CD @5%	267.1

REFERENCE:

Dagaonkar, V.S., and J.D. Malkandale. 1993. Diallel analysis using fixed effect model in upland cotton. Journal of Indian Society for Cotton Improvement, 18: 50-53.

Patil, S.S., and V.V. Pandit. 1991. Use of B  R cross for improving combining ability in sorghum. Golden Jubilee Symposium on Research and Education : Current Trends and the Next Fifty Years, held at New Delhi, p. 397.

Patil, S. S. 1995. Report on the Work Done in the Area of Hybrid Research CIMMYT. The International maize and Wheat Improvement centre El Batan Mexico.

Patil, S. S., and S.A. Patil. 2003. Role of improving combining ability in increasing performance of cotton hybrids. Third World Cotton Research Conference, 9-13 March 2003, held at Cape Town South Africa, pp. 234-238.