AGRICULTURAL COMMUNICATIONS, 24, 2(): 8-6. Heterosis and Inbreeding Depression for Grain Yield and Yield Contributing Characters in Quality Protein Maize. RASHMI JAIN AND DINESH NARAYAN BHARADWAJ* Department of Genetics and Plant Breeding, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur, India. *Corresponding Author: bharadwajdncsau@gmail.com. (Accepted: 5 Oct. 23) ABSTRACT It is important to know the degree and direction of hybrid vigor for its commercial exploitation. Standard heterosis was studied in thirty six crosses of quality maize (Zea mays L.). These crosses showed marked variations in the expression of standard heterosis for yield and yield contributing characters. Grain yield manifested highly significant standard heterosis in three crosses in the positive direction. Standard heterosis ranged from 27.5 to 38.8 for grain yield. The highest heterotic effect among the yield components was for number of cobs per plant followed by cob length, grain rows per cob and cob respectively. The maximum significant positive heterosis was estimated for 54- x R933 (38.8) followed by 394- x HKI-63(2.69) and 24- x HKI-93- (3.83). Inbreeding depression of F2 progenies was also studied for 2 characters of 36 hybrids. Both positive and negative significant inbreeding depressions were found in many crosses for the studied characters. In most of the crosses high heterosis for grain yield and its components was invariably accompanied by high inbreeding depression in F2 generation. Selection of good parents was found to be the most important criteria for developing high yielding quality maize hybrids. Keywords: Hybrid vigor, QPM, standard heterosis, inbreeding depression. Abbreviations: QPM: quality maize INTRODUCTION Cereals are the only source of nutrition all over the world and maize (Zea mays L.) is the most widely cultivated cereal crop in the world after wheat and rice. It is a good source of carbohydrates, fats, s and some of the important vitamins and minerals. Several million people, especially in the developing countries, derive their and calorie requirements from maize. However, inspite of several important uses, maize has an in-built drawback of being deficient in two essential amino acids, viz., lysine and tryptophan. The concept of quality maize (QPM) was first time developed by Vasal (99) at CIMMYT (International center for Maize and Wheat Improvement, Mexico) for which he jointly won World Food Prize in 2. This leads to poor net utilization and low biological value of traditional maize genotypes. To overcome this problem, the maize breeders have developed QPM by incorporating opaque-2 (Mertz et al., 964) mutant gene, which is particularly responsible for enhancing lysine and tryptophan content of maize endosperm. Quality maize has similar taste like normal maize, but it contains nearly double quantity of essential amino acids i.e. lysine and tryptophan, which makes it rich in quality s. The development of high productive potential QPM hybrids is one of the main objectives of plant breeders; therefore the knowledge on the extent of heterosis for grain yield and its contributing components and inbreeding depression (decline in vigor) in the subsequent generations in QPM can be of immense value that can help the breeders to know the gene action responsible for the respective traits in identifying the potential cross combinations which could be exploited commercially and also to choose an appropriate breeding methodology to be used in the subsequent segregating generations for the improvement of desired traits. The present investigation has been, therefore undertaken to study heterosis and inbreeding depression for grain yield and its contributing components in quality maize.
JAIN AND BHARADWAJ MATERIAL AND METHODS Genetic Material: The genetic material for the present investigation comprised of twelve genetically diverse quality maize as female parental inbreds i.e. 79-, 88-, 24-, 394-, 54-, 543-3, 546-, 582-, 64-, 8-, 233- and 298- and 3 testers as male i.e. HKI-63, HKI 93- and R-933 along with their thirty six F s and thirty six F2 s along with HQPM [(check) (as presented in Table )], were grown in a randomized complete block design with three replications during monsoon season of 2 at Oilseed Research Station Kalyanpur, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur, India. All the recommended agronomic practices were adopted for raising a good crop. Measurements: The observations were recorded from randomly taken five and ten competitive individual plants in Fs and F2s respectively and days to tasseling, days to silking, number of leaves per plant, flag leaf area (cm 2 ), days to maturity, plant height (cm), number of cobs per plant, cob length (cm), number of grain rows percob, number of grains per row, cob (gm), grain per cob (gm), -seed (gm), seed yield (gm), shelling %, % in grain (microkjeldahl method given by Bailey, 967), tryptophan % in (Papain hydrolysis method by Hernandez and Bates, 969) and lysine % in (by Hernandez and Bates, 969) were measured. Heterosis Estimation: The heterosis over economic parent was estimated based on formulae given by Turner, (953) and Hayes et al., (955) and inbreeding depression by Miller and Marani (963). Heterosis over check or Standard Heterosis=[( F -CC)/CC] x (Turner, 953 and Hayes et al., 955) Where, F= mean performance of F CC = mean performance of the best commercial check Inbreeding Depression = [(F F2)/F]x (Miller and Marani, 963) Where, F and F2 are the mean values of F and F2 progeny respectively of the same cross for a given character. RESULTS AND DISCUSSION Analysis of variance indicated significant differences among the parents, crosses and parents vs. crosses for all the characters studied indicating significant heterotic response (Table 2). The degree of heterosis varied from cross to cross for all the characters. For any one trait certain crosses expressed considerable high heterosis while it was low in other crosses suggesting the selection of parents based on performance of its cross. Out of thirty six crosses three crosses manifested significant standard heterosis in the positive direction for grain yield per plant. The range of standard heterosis for grain yield was wide from -27.5 to 38.8. The maximum and significant positive heterosis for grain yield was estimated for 54- x R933 (38.8) followed by 394- x HKI- 63(2.69) and 24- x HKI-93-(3.83) over check HQPM (3.84) as shown in Table 3. These crosses also exhibited desirable heterotic response for other traits viz. number of cobs/plants, cob length, grain rows/cob and grain. Such heterosis was also reported by Debnath (984), Jha and Khera (992), Larish and Brewbaker (999), Anantha (24) and Abhishek (26). Significant negative heterosis was considered as desirable one for 5% flowering, 5% silking, days to maturity and plant height. For rest of the traits significant and positive heterosis was considered as desired one. The cross combinations of 79- x HKI-63, 394- x HKI-63 and 298- x HKI-93- recorded the highest desirable standard heterosis (all -.3) for days to 5% tasseling, 543-3 x HKI-63, 8- x HKI-93- and 298- x HKI-93- (all -9.5) for days to 5% silking, 24- x HKI-63, 54- x HKI-63, 64- x HKI-93-, 8- x HKI-93- and 298- x HKI- 93- (all -9.82) for days to maturity, 79- x HKI-93- (-2.72), 79- x R-933 (-.72) and 394- x HKI-93-(-.52) for plant height, 54- x R933 (5.), 394- x HKI-63 (5.) and 24- x HKI-93- (.) for number of cobs per plant, 79- x HKI-93-(26.27), 54- x HKI- 93- (25.85) and 24- x HKI-93- (25.42) for cob length. 543-3 x R933 (23.2), 394- x R933 (5.58) and 24- x R 933 (2.53) for grain rows per cob, 582- x HKI-63 (8.82) for grains per row, 79- x HKI-93- (2.4), 88- x HKI-93- (8.62) and 582- x HKI-93- (8.26) for cob, 394- x HKI-63 (8.86), 543-3 x R933 (8.74) and 546- x HKI-63 (7.57) for grain per cob, 233- x HKI- 93- (4.96), 546- x HKI-93- (4.83) and 88- x HKI-93- (4.9) for -seed, 54- x R933 (38.8), 394- x HKI -93- (2.69) and 24 x HKI-93- (3.83) for seed yield per plant. 394. x HKI-63 (4.24), 546- x HKI-63 (4.6) and 233- x HKI-63 (2.63) for shelling percentage. 24- x HKI-93- (4.53), 24- x R 933 (3.7) and 64- x HKI-93- (8.72) for percentage in grain, 233- x R 933 (6.8), 298- x HKI-93- (4.85) and 394- x R933 (4.85) for tryptophan and 233- x R933 (35.7), 233- x HKI-63 (33.) and 88- x HKI-63 (22.9) for lysine content. 9
AGRICULTURAL COMMUNICATIONS. Table. Mean performance of lines, testers and check with their different characters. Lysine % in.89.53.83.63.45.74.46.67.58.75.65.45.96.73 2.4 2.7 Tryptop han % in.4.34.4.52.3.44.33.52.42.45.63.53.46.43.53.7 Protein % in grain.3 2.45.4 9.56..68 2.24 9.2 8.4 2.53 8..48.75 9.8 8.2.3 Shelling % 66.66 65.58 66.87 7.72 6.72 7.46 7.27 5.89 56.93 56.48 6.56 65.92 72.49 49.92 6.89 75.79 Seed yield 68.62 6.67 78.6 8.68 88.25 92.78 66.5 54.72 72.55 89.35 65.53 72.83 74.5 55.88 66.47 3.84 -seed 24.83 26.93 26.77 27.5 27.5 27.83 28. 27. 27.43 27.33 28. 27.5 27.5 27.77 28.93 25.93 Grain per cob 55.93 6.67 63.33 65.85 64.3 64.47 66.5 54.72 58.97 62.2 65.53 62.7 74.5 55.88 66.47 8.44 Cob 83.9 94.5 94.72 93. 4.2 9.2 94.63 7.53 3.57.2 6.46 94.32 2.28.89 9.6 7.45 of grains per row 8.33 8.67 9.33 9.67 9 9.33 8.67 8.33 7.67 7.33 9.33 8 2.67 7.67 8 22.33 of grain rows per cob 2.6 2.47 2.33 2.27 2.47 2.33 2.87.53 2.53 3.7 2.4 2.87 2.87.87 3.7 3.73 Cob length (cm) 5.47 5.33 5.53 4.4 5.53 4.53 4.53 3.3 4.8 4.33 4.5 4.53 4.67 6.67 4.33 5.73 of cobs per plant.33.33.33.47.53.33.53.27.33 Plant height (cm) 2.5 8.3 9.83 8. 7.27 6.43 8.33 2.7 8.77 7.3 8.53 7.43 25.53 2.3 22.3 48.54 maturity 94.67 92.33 9.33 9.33 92.67 92.33 92.67 93.67 93 92 93.67 92.67 87 89 89.67 9.67 Flag leaf area (cm 2 ) 57.6 62.27 6.8 63.47 62.53 6.3 62.23 62.87 62.27 62.47 62.57 62.27 63.27 6.6 6.97 63.63 of leaves per plant 2.73.47 9.8.43.67.47.53.4.4.33.47.7.47.93 9.93 3.47 silking 62.67 56.33 57.33 58.33 58.67 55.33 58.67 55.67 59 55 57.67 56.67 5.67 52 55 54.67 tasseling 59.67 54.33 55.33 56.33 56.67 53.33 56.67 53.67 57 53 55.67 54.67 5 5 52 52.67 Lines 79-88- 24-394- 54-543-3 546-582- 64-8- 233-298- Testers HKI-63 HKI-93- R933 Check HQPM-
JAIN AND BHARADWAJ Source of variation Replicates Treatments Parents Parents (Line) Parents (Testers) Parents (L vs T) Parents vs Error Total d.f. 2 5 4 2 35 52 5% taseling.4 5.64 9.42.76 3. 47.6 274. 6.74.55 5.5 5% silking.96 8.43 23.33 3.26. 6.56 26.2 9.57.55 6.44 of leaves per plant.22 2..72.72.75 3.56 52.34.83.26.87 Flag leaf area (cm 2 ).49 3.24 6.3 7.28 2.3.8* 5.7.88.23 4.5 Table 2. ANOVA for different characters in Maize. maturity Plant height (cm) of cobs per plant Cob length (cm) of grain rows per cob of grains per row Cob.73.89..2.94.35 6.68 7.44 63.3.8 3.5.83* 6.82 63.29.85 24.93.4.8.54 2.43 2.84 2.82.46.3.28.45.6 94.53 5.78 2.92 4.78.24 8. 73.56 23.34 8.2.49.72..4 678.8 647.48 2,523.26.32 87.37 7.47 73.2 2588.74.68 8.36.5.79.76 6.68 74.57.56.36..9.52.6 5.84 6. 2.7.3.22.63 3.3 57.64 *and denote significance at 5% and % levels, respectively. Grain per cob.49 9.5 76.7 43.53 252.36 8.46 786.43 35.89.5 63.55 - seed.95.93 2.36 2.24.74 4.87 47.5.47.3.85 Seed yield 9.45 44.5 49.9 423.68 252.36 573.48 4264.94 29.54 5.53 36.7 Shelling % 4.2 5.33 54.75 22.85 382.5 5.88 2243. 9.2 2.8 5.68 Protein % in grain 3.27 6.89 7.2 4.94 7.36 4.5.5..8 Tryptop han % in.2.2.3...2.. Lysine % in.5.2.7.2.67 2.8.8.5
AGRICULTURAL COMMUNICATIONS. Table 3. Estimates of standard heterosis and Inbreeding Depression. 5% taseling 5% silking maturity Plant height (cm) of cobs per plant S.H I.D. S.H I.D. S.H I.D. S.H I.D. S.H I.D. 79- x HKI-63 -.3-4.93-7.93-4.64-6.9-2.73 -.9 4.42-25.. 79- x HKI-93- -5.7-4.7 * -3.5-3.77-8.36-4.76-2.72 4.2-25.. 79- x R933-4.43-6.62-2.44 * -6.25-6.9-3.9 -.72 4.25-25.. 88- x HKI-63-4.43. -4.27. -9.9-2.8-8.66 4.6-25.. 88- x HKI-93- -6.96-4.8-6.7. -8.36-3.57 * -.9 4. -25.. 88- x R933-6.33-4.5 * -6.. -6.9-3.52 -. 4.8-25.. 24- x HKI-63-7.59-2.5-7.32 -.97-9.82-4.84-6.63 4.83-25.. 24- x HKI-93- -4.43-2.65 * -4.27-2.55 * -9.9-3.6-9.67 4.29. 9.9 24- x R933-3.8-5.92 -.83-5.59-7.64-3.54-9.67 3.92-25.. 394- x HKI-63 -.3-6.34-7.93 -.99-8. -2.37 * -8.86 4.5 5. 3.4 394- x HKI-93- -8.86-6.25 * -8.54-4. -9.45-3.6 * -.52 2.67-5.. 394- x R933-7.59-6.6-7.32-5.92-8.73-4.78 -.64 3.75-25.. 54- x HKI-63-7.59-4.79 * -7.32-4.6 * -9.82-5.24-9.38 3.94-25.. 54- x HKI-93- -3.8-3.95 * -3.66-3.8 * -6.55-3. * -.4 3.89-25.. 54- x R933-2.53 * -7.4-2.44 * -6.88-5.82 -.93 -.62 3.92 5.. 543-3 x HKI-63-9.49-4.2 * -9.5-2. -8.73-3.59-9.3 4.3-25.. 543-3 x HKI-93- -7.59-4. * -5.49-3.87 * -7.64-3.54 -.43 4.3-25.. 543-3 x R933-6.33-6.8-6. -5.84-8. -4.74 -.73 4. -25.. 546- x HKI-63-6.33-4.73-6. -4.55-9.9-4. -8.63 4.2-25.. 546- x HKI-93- -2.53 * -3.9 * -2.44 * -3.75 * -9.9-4.8 -.36 3.7-25.. 546- x R933-4.43-7.28-4.27-7. -9.9-4.4 -.73 3.65-25.. 582- x HKI-63-3.8 -.97-3.66 -.9-7.64-3.54-8.2 4. -25.. 582- x HKI-93- -6.33-4.5 * -6. -3.9 * -8. -3.56 -.28 3.94-25.. 582- x R933-3.6-5.88 * -3.5-5.66 * -9.45-4.82 -.73 3.33-25.. 64- x HKI-63-2.53 * -4.55-2.44 * -4.37-4.73 -.53 * -8.5 4. -25.. 64- x HKI-93- -3.8-3.95 * -.83-3.73 * -9.82-4.84 -.4 3.6-25.. 64- x R933-4.43-7.28-4.27-7. -8. -4.35 -.35 3.77-25.. 8- x HKI-63-7.59-2.5-7.32 -.97-7.64-3.54-8.99 4.8-25.. 8- x HKI-93- -9.49-4.2 * -9.5-4.3 * -9.82-4.84 -.4 3.93-25.. 8- x R933-7.59-6.6-5.49-5.8-8.73-3.59 -.5 4.2. 2.5 233- x HKI-63-8.23-4.83-7.93-4.64-8. -3.95-8.39 4.2-25.. 233- x HKI-93- -5.7-4.3 * -3.66-3.8 * -8.73-4.78 -.96 3.88-25.. 233- x R933-8.23-8.27-6. -7.79-9.9-4.8 -.42 3.78-25.. 298- x HKI-63-7.59-4.79-5.49-4.52-8.73-3.98 * -6.67 5.25 -.. 298- x HKI-93- -.3-4.23 * -9.5-5.37-9.82-5.65 -.89 4.2-25.. 298- x R933-9.49-6.99-7.32-5.26-7.64-4.33 -.28 4.6-5. 3.95 *and denote significance at 5%and % levels, respectively. 2
JAIN AND BHARADWAJ Table 3 (Continue). Estimates of standard heterosis and Inbreeding Depression. Cob length (cm) of grain rows per cob of grains per row Cob Grain per cob S.H I.D. S.H I.D. S.H I.D. S.H I.D. S.H I.D. 79- x HKI-63 3.4 7.68 * 4.52 5.29. 7.35 2.5.68 6.94 4.5 79- x HKI-93-26.27 9.56 * 3.52 4.85 -.47.45 2.4.72 4.27 8.3 79- x R933 4.83 8.76 *.56 * 7.2-7.35 6.35 6..6 3.32 5.2 88- x HKI-63 3.56 8.2-2. 2.5 4.4 8.45 * 7.49 6.79 3.73.56 88- x HKI-93-24.58 9.8 -. 3.5 2.94.43 * 8.62 8.96 6. 7.27 88- x R933 2.7 8.8 -.5.2 5.88.8 * 5.86 8.53 5.86 4.34 24- x HKI-63 4.4 8.6 9.5 9.68-4.4 4.62 4.2 5.27 4.44.34 24- x HKI-93-25.42 9.2 2.5 5.88 2.94. 6.34 8.2 6.82 7.2 24- x R933 3.56 8.2 2.56 * 7.59-7.35 6.35 7.89 5.32 4.44 3.44 394- x HKI-63.7 8.8 3.2 4.39 4.4 7.4 4.3 5.56 8.86 2.2 394- x HKI-93-22.67 2.35 4.2 5.3. 5.88.2 8.42 * 5.78. 394- x R933.7 8.56 5.58 9.3 -.76 3.33 5.88 4.83 *.4.39 54- x HKI-63 2.7 7.42 * 2. 2.96.47 7.25 2.42 2.35 4.53. 54- x HKI-93-25.85 9.34 5.3 5.74 -.47 8.96.5 4.4 * 4.2 5.94 54- x R933 3.4 8.52-4.52.5 -.47 8.96 * 6.53 4.2 *.8 9.32 543-3 x HKI-63 7.84 6.97 * -.5.53. 5.88.73 4.77.52. 543-3 x HKI-93-2.9 9.9 -.5 -.5 4.4 9.86.22 6.64 5.53 6.34 543-3 x R933 8.9 7.88 * 23.2.94-3.24 3.39.3 3.45 8.74.25 546- x HKI-63 7.2 6.72 * 2.5 2.94.47 8.7 3.5 * 4.79 7.57.53 546- x HKI-93-22.3 9.37 * 3.2 4.39-5.88 7.8 9.2 5.26 9.86 4.3 546- x R933.7 8.37 3.2.46 -.76 2.5 -.87.9 2.43 8.9 * 582- x HKI-63 9. 9.26-6.3.7 8.82 * 9.46 6.64 3.8 4.2 3.56 582- x HKI-93-2.82.9 3.2 8.29-4.4 5.54 8.26 2.3 * 8.5 6.86 582- x R933 8.9 9.67 -. 2.3.47 8.9.45.2 *. 4.77 64- x HKI-63 9.53 7.25 * -6.3. 2.94 8.57 *.7.62 * 6.98 9.92 64- x HKI-93-22.46 9.7. 2.5-4.4 6.92 2.64 4.82 4.48 4.43 64- x R933 9. 7.57 9.5 5.53 -.76 2.67 7.9 2.88 7.77 2.44 8- x HKI-63 7.63 7.9-5.53.6.47.4 * -3.32 * -.9 * 2.56 7.2 * 8- x HKI-93-2.6 9.49 2.5 3.92-7.35 3.8 5.5.66 * 4.23 * 5.77 8- x R933.2 8.2 -.5 5. 2.94. 7.42 5.9 3.2 3.3 233- x HKI-63 9.32 7.6-6.3.7 7.35 8.22 * 2.8 8.73 * 5..97 233- x HKI-93-8.86 8.32-6.53.8. 8.82 * 6.37.53 * 6.9 3.3 233- x R933 7.84 7.5-5.3.53 2.94 25. * 5.32 8.37 9..2 298- x HKI-63 8.26 7.4. 4.2.47 8.7 4.64 2.42 * 4.23.59 298- x HKI-93-9.92 8.66-2.5 4.2 4.4.27 4.5 7.43 * 5.28 6.89 298- x R933 8.69 7.8 * 7.54 5.4-5.88 7.8 9.39 6.2 3.36 3.4 *and denote significance at 5%and % levels, respectively. 3
AGRICULTURAL COMMUNICATIONS. Table 3 (Continue). Estimates of standard heterosis and Inbreeding Depression. -seed Seed yield Shelling % Protein % in grain Tryptophan % in S.H I.D. S.H I.D. S.H I.D. S.H I.D. S.H I.D. 79- x HKI-63 3.7 4.97 * -6.83.6 4.26 3.88-28.9-26.5-9.22 4.44 79- x HKI-93-2.92 4.63-8.72 6.24-5.59 7.47-2. -8.4-9.42.84 * 79- x R933 2.92 3.65 * -9.4 2.8-2.32 5.5-22.65-2.74-8.93 7.9 88- x HKI-63 3.7 3.8 * -9..56 5.79 5.2 6.83-4.4-23.79 2. 88- x HKI-93-4.9 3.38-7.42 7.27-2.2 9.3-28.76-25.6-26.2 3.6 88- x R933.25.4-7.6 4.34 -. 6.35-7.9-2.65-39.32-3.2 24- x HKI-63. 2.4-8.6 9.46 9.82 6.4 -.86-2.97-7.77 6.32 24- x HKI-93-2.28 2.72 3.83 2.52.4 9.79 4.53 8.2-34.95 2.99 24- x R933 2.66.9-8.6.96 6.6 8.58 3.7 9.83-24.27 4.49 394- x HKI-63.87 5.82 2.69 2.74 4.24 6.95-7. -4.42-9.7 9.68 394- x HKI-93-.5 2. * -3.82.45 4. 2.94.33 -.33-32.52-3.6 394- x R933 2.28. -2.48 9. * 4.23 6.88-8.3.95 * 4.85 * 3.89 54- x HKI-63 2.66 2.49-8.55 5.5 *.79 8.97.6 -.5 * -47.57-4.63 54- x HKI-93-2.66 2.27 * -8.9 8.8 2.68 * 2.42-9.5-2.4-36.89 6.92 54- x R933.38.4 38.8 25.42-5.2 5.33 * -7. -4.72-23.3.76 543-3 x HKI-63 3.55 2.59-2.68.46.7 5.52 -.7-3.32-3.55 2.3 543-3 x HKI-93-3.7 2.9-7.84 8.52 4.8.4-9.7 -.8-2.36 8.2 543-3 x R933 3.94.54-5.55.5 7.9 7.4-5.72-5.7-32.4-2.4 546- x HKI-63 2.92 2. -6.38.53 4.6 7.7.23-7.8-34.95 5.22 546- x HKI-93-4.83 2.66-2.87 4.3.66 9.25-5.89-3.37-9.42 4.46 546- x R933 4.9 5.6-27.5 8.9 * 4.36 7.35-3.37-8.77-24.76 9.3 * 582- x HKI-63 2.53 2.77 * -8.9 3.56 6.9.56-4.58 -.8 * -.9.8 * 582- x HKI-93-2.2 2.33-23.8 6.86-8.58 5.34-3.8 2.59-3..6 582- x R933 2.92.72 * -2.98 4.77.57 5.6-2.42 5.78-22.82. 64- x HKI-63.64 2. -23.9 7.53 * 6.22 8.45-2.6-9.58-7.28 5.8 64- x HKI-93-2.5 2. * -25.69 6.72 * -7.26. 8.72.34-32.4 3.57 64- x R933 2.66.33-23.35 4.34 -.4 -.5-6.24 6.54-24.27 3.85 8- x HKI-63 2.53 2.58 * -27.6 -.48 6.7 8.94-2.69-9.54-9.9.3 8- x HKI-93-3.4 2.56-25.87 8.23 * -9.42 5.64-9.44-7.4-23.79.83 * 8- x R933 2.66.4 -.89.3-3.76 7.85-29.92-23.62 -.46 4.29 233- x HKI-63 3.7 2.9-8.3.97 2.63 2.25-2. -3.3 4.37.63 233- x HKI-93-4.96 2.7 * -23.97 3.3.48.97-3.2 5.88-4.37.5 233- x R933 3.55 5.6-22.4.2 3.58 2.63-24.98-3.8 6.8. 298- x HKI-63 3.94 3.2 -.5 8. 9.6 -.24-6.7-6.26-9.7 9.4 298- x HKI-93-.89.94-8. 4.6.69.24 -.84-5.46 4.85 * 5.74 298- x R933 4.9.93 * -5.54 2.89 3.6 7.86-8.6 -.65-8.25 6.88 * *and denote significance at 5%and % levels, respectively. 4
JAIN AND BHARADWAJ Table 3 (Continue). Estimates of standard heterosis and Inbreeding Depression. Lysine % in Lysine % in Lysine % in S.H I.D. S.H I.D. S.H I.D. 79- x HKI-63 3.4.52 54- x HKI-63-3.68-8.37 64- x HKI-63 7.3 5.5 79- x HKI-93-.46 8. 54- x HKI-93- -3.86.74 64- x HKI-93- -5.26* 9.46 79- x R933-9.2 -.2 54- x R933.85 9. * 64- x R933-5.* 4.72 88- x HKI-63 22. 6.58 * 543-3 x HKI-63-4.37.36 8- x HKI-63. 7.26 88- x HKI-93- -9.2 8.6 543-3 x HKI-93-.46.5 8- x HKI-93- -4.48* 7.2 88- x R933-23.65-6.7 543-3 x R933-5.77-3.2 8- x R933 27.5 4.67 24- x HKI-63 4.95 * 7.95 546- x HKI-63 -.82 5.89 233- x HKI-63 33.8 8.58 24- x HKI-93- -8.5 4.73 546- x HKI-93-5.72 5.6 233- x HKI-93-8.5 3.68 24- x R933-2.6 2.84 546- x R933-4.2* 6.28 233- x R933 35.7 7.77 394- x HKI-63 8.5.54 582- x HKI-63 9.58.7 298- x HKI-63 2.32.3 394- x HKI-93-3.55 9.7 582- x HKI-93-3.76 5.35 * 298- x HKI-93-7. 5.73 394- x R933-4.2* 4.9 582- x R933. 6.3 298- x R933 -.93 8. *and denote significance at 5%and % levels, respectively. The maximum inbreeding depression was recorded in 54- x HKI-93- (2.42) for shelling percentage, 64- x HKI-93- (.34) for percentage, 24- x HKI-63 (6.32) for tryptophan percentage and 233- x HKI-63 (8.58) for lysine content. This may be attributed due to non-additive gene effects. Therefore selection for cross combination would be effective for improvement of these traits by developing hybrid varieties. The present study thus suggests that hybrid vigor / heterosis of even small magnitude for individual yield component may have additive effect on economic yield. The cross combinations exhibiting high heterosis coupled with high inbreeding depressions in F2 generation for the traits indicated non-additive gene action. This gene action can be fully exploited only by developing hybrid cultivars. However, the cross combinations showing high heterosis followed by low inbreeding depression could be utilized to develop superior inbred lines which could be further utilized to exploit in hybridization programs. CONCLUSION Our results indicate that among the 36 heterotic crosses, three combinations viz., 54- x R933 followed by 394- x HKI-63 and 24- x HKI- 93- showed significant and positive standard heterosis over HQPM for grain yield and these could be exploited commercially as quality maize (QPM) hybrids. Abhishek, K. 26. Evaluation of newly developed inbred lines for per se performance and combiningability in maize (Zea mays L.). M.Sc. Thesis, University of Agricultural Sciences, Bangalore, India. 4pp. Anantha, M.S. 24. Combining ability and molecular diversity analysis in maize inbreds. M.Sc. Thesis, University of Agricultural Sciences. Coimbatore, India. 6pp. Bailey, J.L. 967. Miscellaneous alytical methods. pp: 34-346. In: Bailey, J.L. (ed.). Techniques in Protein Chemistry. Elsevier Science Publishing. New York, USA. Debnath, S.C. 984. Heterosis in maize I: grain yield and some of its attributes. Bangladesh Journal of Agricultural Research. 9 (2): 78-83. REFERENCES Hayes, H.K., F.R. Immer and D.C. Smith. 955. Methods of Plant Breeding. Mc. Graw Hill Book Inc., New York, USA. Hernandez, H.H. and L.S. Bates. 969. A modified method for rapid tryptophan analysis of maize. CIMMYT Research Bulletin. CIMMYT, Mexico City, Mexico. 3: 7. Jha, P.B. and A.S. Khera. 992. Evaluation of maize inbred lines derived from two heterotic populations. Indian Journal of Genetics and Plant Breeding. 52(2): 26-3. Larish, L.L.B. and J.L. Brewbaker. 999. Diallel analyses of temperature and tropical popcorns. Maydica. 44(4): 279-284. Mertz, E.T., L.S. Bates and O. Nelson. 964. Mutant gene 5
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