الفهرس 
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Abstract
VI. SUMMARY
This study was carried out during the two growing seasons 2018 and 2019 at the Agronomy Department Experimental farm, faculty of Agriculture, Assiut University using one yellow maize population (IY376, imported from India 1969) to study the effect of water stress on agronomic traits, line × tester interaction and combining ability using 100 S1-lines and two testers namely, SC162 and TWC352.
The obtained results are summarized as follows:
Line × testers analysis
Under normal condition, results showed significant differences for all studied traits of parents and parents vs crosses. In addition, crosses showed significant differences for all studied traits except anthesis-silking interval (ASI). For lines, significant differences were detected only for days to 50% silking (DS), ear height (EH) and ear diameter (ED). For testers, significant differences were found in all traits except anthesis-silking interval (ASI), ear length (EL), ear diameter (ED) and number of rows per ear (NRE). finally, for line × tester, all traits showed significant differences except days to 50% silking (DS), anthesis-silking interval (ASI), and ear diameter (ED). Under water stress condition, results showed significant differences for all studied traits for parents and parents vs crosses. In addition, crosses showed significant differences for all studied traits. For lines, significant differences were detected only for days to 50% silking (DS), ear diameter (ED) and grain yield per plot (GY). For testers, significant differences were found in all traits except anthesis-silking interval (ASI), and number of rows per ear (NRE). Finally, for line × tester, all traits showed significant differences except days to 50% silking (DS), and ear diameter (ED).
Days to 50% anthesis
Under normal condition, data exhibited that four S1-lines took less than 60 days to 50 % anthesis, while most of them took more than 60 days to %50 anthesis. For the testers, TWC352 was earlier in anthesis date than SC162. For the top-crosses, results showed that the top-crosses involving TWC352 were earlier in anthesis date than those involving SC162.The S1-lines 80 and 88 possessed negative (desirable) and significant GCA effects for days to %50 anthesis toward earliness with values of –3.11 and –3.28, respectively. The top-crosses including S1-line 53 ×SC162 and S1-line 28 ×TWC352 were good specific combiners. Moreover, the broad sense heritability value was 0.5293.
Under water stress condition, data displayed that there were three S1-lines took less than 60 days to 50 % anthesis, while most of them took more than 60 days to %50 anthesis. For the testers, TWC352 was earlier in anthesis date than SC162. For the top-crosses, results showed that all top crosses involving TWC352 were earlier in anthesis date than those involving SC162.The S1-lines 80 and 88 showed negative (desirable) and significant effects of GCA with values of –2.70 and –3.03, respectively. The top-crosses including S1-line 91×SC162, S1-line 7×TWC352 and S1-line 20 ×TWC352 were good specific combiners and the broad sense heritability value was 0.5968.
Days to 50% silking
Under normal condition, data showed that S1-lines 29 and 30 were earlier than the other S1-lines to 50 % silking. For the testers, TWC352 was earlier in silking date than SC162. For the top-crosses, results showed that all the top-crosses involving TWC352 were earlier in silking date than those
involving SC162. The S1-lines 80 and 88 showed negative (desirable) and significant GCA effects with value of – 2.43 and – 3.26, respectively. None of the top-crosses showed any significant effects for days to 50% silking under normal condition. Moreover, the broad sense heritability value was 0.0807.
Under water stress condition, data displayed that S1-lines 29 and 80 were earlier than the other S1-lines to 50 % silking. For the testers, TWC352 was earlier in silking date than SC162. For the top-crosses, results showed that all top crosses involving TWC352 were earlier in silking date than those involving SC162. The S1-lines 80 and 88 showed negative and significant effects of GCA with values of – 2.29 and – 3.13, respectively. None of the top-crosses showed any significant effects for days to 50% silking under water stress condition and the broad sense heritability value was 0.1392.
Anthesis-silking interval
Under normal condition, data exhibited that S1-lines 89 and 93 had longer ASI than the other S1-lines. For the testers, SC162 has shorter anthesis-silking interval than TWC352. For the top-crosses, results showed that top-crosses involving TWC352 had shorter anthesis-silking interval than those involving SC162. The S1-line76 showed negative and significant GCA effects with value of – 0.98. The top-cross including S1-line 43 ×TWC352 was good specific combiners and the broad sense heritability value was 0.1214.
Under water stress condition, data displayed that S1-lines 13, 47 and 79 had longer ASI than the others. For the testers, SC162 has shorter anthesis-silking interval than TWC352. For the top-crosses, results showed that the top-crosses involving TWC352 had longer anthesis-silking interval than those involving SC162.The S1-lines 45 and 66 showed negative and significant effects of GCA with the same values of – 0.93. The top-crosses including S1-
line 7 × SC162, S1-line 17 × SC162 and S1-line 54 × TWC352 were good specific combiners. Moreover, the broad sense heritability value was 0.4275.
Plant height
Under normal condition, data exhibited that S1-lines 21 and 58 possessed the highest plant height. For the testers, SC162 had higher plant height than TWC352. For the top-crosses, results showed that top-crosses involving TWC352 had higher plant height than those involving SC162. The S1-lines 26 and 73 showed negative and significant GCA effects with value of – 0.26 and – 0.30, respectively. None of the top-crosses showed any significant effects for plant height under normal condition and the broad sense heritability value was 0.9969.
Under water stress condition, data displayed that the highest values of plant height were observed in S1-lines 58 and 85. For the testers, SC162 had higher plant height than TWC352. For the top-crosses, results showed that top-crosses including TWC352 had higher plant height than those involving SC162. The S1-lines 26 and 87 showed negative and significant effects of GCA with values of – 0.24 and – 0.22, respectively. The top-crosses including S1-line 70 ×SC162 and S1-line 88 × TWC352 were good specific combiners.
Moreover, the broad sense heritability value was 0.8214.
Ear height
Under normal condition, data exhibited that S1-lines 1 and 76 possessed the highest ear height. For the testers, SC162 had higher ear height than TWC352.For the top-crosses, results showed that top-crosses involving TWC352 had higher ear height than those involving SC162. The S1-lines S1-lines 73 and 92 showed negative and significant GCA effects with value of –
0.17 and – 0.23, respectively. The top-crosses including S1-line 29 × TWC352 and S1-line 91 × SC162 were good specific combiners. Moreover, the broad sense heritability value was 0.9990.
Under water stress condition, data displayed that the highest values of ear height were observed in S1-lines 13, 41 and 85. For the testers, SC162 had higher ear height than TWC352. For the top-crosses, results showed that top-crosses including TWC352 had higher ear height than those involving SC162. The S1-lines 26 and 92 showed negative and significant effects of GCA with values of – 0.15 and – 0.17, respectively. The top-crosses including S1-line 87 ×SC162 and S1-line 100 ×TWC352 were good specific combiners and the broad sense heritability value was 0.9992.
Ear length
Under normal condition, data exhibited that S1-lines 4 and 41 possessed the longest ear length. For the testers, SC162 had longer ears than TWC352. For the top-crosses, results showed that the top-crosses involving TWC352 had longer ears than those involving SC162. The S1-lines 4 and 20 displayed positive and significant GCA effects for EL towards with value of 1.40 and 2.11 respectively. The top-cross including S1-line 4×SC162 and S1-line 78×TWC352 were good specific combiners. Moreover, the broad sense heritability value was 0.7318.
Under water stress condition, data displayed that the longest values of ear length were observed in S1-lines 58 and 81. For the testers, SC162 had longer ears than TWC352. For the top-crosses, results showed that the top-crosses including TWC352 had longer ears than those involving SC162. The S1-lines 12 and 98 displayed positive and significant GCA effects for EL towards with values of 1.81 and 2.09, respectively. The top-crosses including
S1-line 94 ×SC162 and S1-line 52 ×TWC352 were good specific combiners and the broad sense heritability value was 0.7008.
Ear diameter
Under normal condition, data exhibited that S1-lines 10 and 40 had thicker ears than the other S1-lines. For the testers, SC162 had thinner ears than TWC352. For the top-crosses, results showed that top-crosses involving TWC352 had thicker ears than those involving SC162. The S1-lines 2 and 57 displayed positive and significant GCA effects for ED towards with values of 0.31 and 0.33, respectively. Under normal condition, none of the top-crosses showed any significant effects for ear diameter and the broad sense heritability value was 0.9990.
Under water stress condition, data displayed that the thickest values of ear diameter were observed in S1-lines 34 and 41. For the testers, TWC352 had thinner ears than SC162. For the top-crosses, results showed that top-crosses including SC162 had thinner ears than those involving TWC352. The S1-lines 45 and 61 displayed positive and significant GCA effects for ED towards with values of 0.33 and 0.41, respectively. Under water stress condition, none of the top-crosses showed any significant effects for ear diameter. Moreover, the broad sense heritability value was 0.9979.
Number of rows per ear
Under normal condition, data exhibited that S1-lines 8 and 43 possessed the highest number of rows per ear. For the testers, SC162 had higher number of rows per ear than TWC352. For the top-crosses, results showed that top-crosses involving TWC352 had higher number of rows per ear than those involving SC162. The S1-lines 24 and 68 displayed positive
and significant GCA effects for NRE towards with value of 1.83 and 1.95 respectively. The top-crosses including S1-line 64 ×SC162 and S1-line 18 ×TWC352 were good specific combiners. Moreover, the broad sense heritability value was 0.5573.
Under water stress condition, data displayed that the highest values of number of rows per ear were observed in S1-lines 14, 34. For the testers, TWC352 has lower number of rows per ear than SC162. For the top-crosses, results showed that top-crosses including SC162 had higher number of rows per ear than those involving TWC352. Both S1-lines 7 and 86 displayed positive and significant GCA effects for ASI towards with the same values of 1.50. Top-cross including S1-line 11 ×TWC352 was good specific combiners and the broad sense heritability value was 0.3875.
100-grain weight
Under normal condition, data exhibited that S1-lines 56 and 88 possessed the highest 100-grain weight. For the testers, SC162 had higher 100-grain weight than TWC352. For the top-crosses, results showed that top-crosses involving TWC352 had higher 100-grain weight than those involving SC162. The S1-lines 10 and 99 displayed positive and significant GCA effects for 100-GW towards with value of 2.10 and 2.37 respectively. The top-cross including S1-line 29×SC162 and S1-line 75×TWC352 were good specific combiners and the broad sense heritability value was 0.7798.
Under water stress condition, data displayed that the highest values of 100-grain weight were observed in S1-lines 34 and 86. For the testers, TWC352 has lower 100-grain weight than SC162. For the top-crosses, results showed that the top-crosses including TWC352 had higher 100- grain weight than those involving SC162. The S1-lines10 and 66 displayed positive and
significant GCA effects for 100-GW towards with values of 2.94 and 2.40, respectively. The top-crosses including S1-line 29×SC162 and S1-line 83×TWC352 were good specific combiners. Moreover, the broad sense heritability value was 0.7521.
Grain yield per plot
Under normal condition, data exhibited that S1-lines 65 and 68 possessed the highest grain yield per plot. For the testers, SC162 has higher grain yield per plot than TWC352. For the top-crosses, results showed that top-crosses involving TWC352 had higher grain yield per plot than those involving SC162. Twenty-eight S1-lines exhibited positive and significant GCA effects for GY. The top-crosses including S1-line 29×SC162 and S1-line 78×TWC352 were good specific combiners and moreover, the broad sense heritability value was 0.8421.
Under water stress condition, data displayed that the highest values of grain yield per plot were observed in S1-lines 76, 81and 88. For the testers, TWC352 has lower grain yield per plot than SC162. For the top-crosses, results showed that the top-crosses including TWC352 had higher grain yield per plot than those involving SC162.Eighteen S1-lines exhibited positive and significant GCA effects for GY. The top-crosses including S1-line 86×SC162 and S1-line 70×TWC352 were good specific combiners. Moreover, the broad sense heritability value was 0.7500.
Genetic components and heritability
Under normal condition, heritability in broad sense was higher than under water stress condition for all traits except days to 50%anthesis, days to 50%silking, anthesis-silking interval and ear height. Under normal and water stress conditions, specific combining ability variance was important than
general combining ability variance for all traits except plant height, ear height and ear diameter indicating preponderance of dominance variance in controlling these characters.
VII. REFERENCES
Abrha, S. W., Zeleke, H. Z., & Gissa, D. W. (2013). Line x tester analysis of maize inbred lines for grain yield and yield related traits. Asian journal of plant science and research, 3: 12-1