scholarly journals Flowering, reproductive behaviors and their effects on grain yields of newly bred single cross hybrids of yellow maize (Zea mays L.) in winter in subtropical Nepalese Himalayan foot plain

2015 ◽  
Author(s):  
Nav Raj Adhikari ◽  
Surya Kant Ghimire ◽  
Shrawan Kumar Sah ◽  
Keshab Babu Koirala
Keyword(s):  
Reproductive Behavior ◽  
Plant Population ◽  
Reproductive Behaviors ◽  
Stressful Environment ◽  
Maize Population ◽  
Single Cross ◽  
Apical Node ◽  
Male Organ ◽  
Kernel Set ◽  
Single Cross Hybrids

Introduction: All the plants of a maize population or hybrid PP (plant population) do not dehisce anthers and do not emerge silk simultaneously. Generally, male flowering or anther dehiscence (anthesis) is leading and female flowering (silk emergence or silking) is lagging under both conducive and stressful environment. Enough and timely pollen availability is indispensible when silks come out of maize ears for largest number of kernel set. So, study of flowering and reproductive behavior of newly bred maize hybrids are indispensible to confirm high grain yielding hybrid with trait of simultaneous anthesis and silking (synchrony). Materials and methods: Flowering and reproductive behaviors of fifteen newly bred single cross hybrids of yellow maize have been examined in winter growing them in an RCBD trial planting their seeds on October 3, 2012 in subtropical foot plain of Himalaya. For flowering (FB); emergence of male organ (emergence of tassel or tasseling or TSS) from apical node of the stem, anthesis, silking, browning of silk or withering of silk (silk senescence or S SEN), tassel-anthesis interval (TAI), anthesis-silking interval (ASI), silking-silk senescence interval (S INI-S SEN Interval) of the hybrids have been examined dissecting the plant population (PP) into four equal parts (percent) as the first earliest, second earliest, third earliest and terminal 25% of the PP denominated as 25, 50, 75 and 100% respectively of the each of the fifteen hybrids. So, whether third earliest 25% and terminal 25% silk emerging PP denominated as SILK 75 and SILK 100% respectively will get enough pollen from the PP of the same hybrid can be determined through ASI 75 and ASI 100 of the hybrid PP. Results and discussion: A polynomial grain yield estimating regression equation (t ha-1) Y = - 11922 + 507.3*(TSS25) - 7.183*(TSS25)2 + 0.03387*(TSS25)3 with r2 value 66% has been discovered from days taken for TSS25 (TSS of earliest 25% PP). Similarly, high r2 bearing polynomial equations were from days for anthesis and silking of the PPs of the fifteen hybrids. Equations with the lowest r2 were for the days required for the silk senescence (S SEN). Reason of low r2 is that the observation of silk browning or withering could not be precise for naked eye since the silks looked fresh longer in high humidity, low temperature and cloudy day in the winter although it lost receptivity earlier. In addition, Interval duration from S INI to S SEN cannot be the duration of silk receptivity in the winter of subtropical Nepalese Himalayan foot plain. For reproductive behavior; number of functional egg cells that became successful zygotes to pull assimilates for complete kernel development can reflect aroma about reproductive strength (RS) of the hybrid. Accordingly, hybrids 8 and 5 have been found of the highest RS.

scholarly journals Flowering, reproductive behaviors and their effects on grain yields of newly bred single cross hybrids of yellow maize (Zea mays L.) in winter in subtropical Nepalese Himalayan foot plain

2015 ◽  
Author(s):  
Nav Raj Adhikari ◽  
Surya Kant Ghimire ◽  
Shrawan Kumar Sah ◽  
Keshab Babu Koirala
Keyword(s):  
Reproductive Behavior ◽  
Plant Population ◽  
Reproductive Behaviors ◽  
Stressful Environment ◽  
Maize Population ◽  
Single Cross ◽  
Apical Node ◽  
Male Organ ◽  
Kernel Set ◽  
Single Cross Hybrids

Introduction: All the plants of a maize population or hybrid PP (plant population) do not dehisce anthers and do not emerge silk simultaneously. Generally, male flowering or anther dehiscence (anthesis) is leading and female flowering (silk emergence or silking) is lagging under both conducive and stressful environment. Enough and timely pollen availability is indispensible when silks come out of maize ears for largest number of kernel set. So, study of flowering and reproductive behavior of newly bred maize hybrids are indispensible to confirm high grain yielding hybrid with trait of simultaneous anthesis and silking (synchrony). Materials and methods: Flowering and reproductive behaviors of fifteen newly bred single cross hybrids of yellow maize have been examined in winter growing them in an RCBD trial planting their seeds on October 3, 2012 in subtropical foot plain of Himalaya. For flowering (FB); emergence of male organ (emergence of tassel or tasseling or TSS) from apical node of the stem, anthesis, silking, browning of silk or withering of silk (silk senescence or S SEN), tassel-anthesis interval (TAI), anthesis-silking interval (ASI), silking-silk senescence interval (S INI-S SEN Interval) of the hybrids have been examined dissecting the plant population (PP) into four equal parts (percent) as the first earliest, second earliest, third earliest and terminal 25% of the PP denominated as 25, 50, 75 and 100% respectively of the each of the fifteen hybrids. So, whether third earliest 25% and terminal 25% silk emerging PP denominated as SILK 75 and SILK 100% respectively will get enough pollen from the PP of the same hybrid can be determined through ASI 75 and ASI 100 of the hybrid PP. Results and discussion: A polynomial grain yield estimating regression equation (t ha-1) Y = - 11922 + 507.3*(TSS25) - 7.183*(TSS25)2 + 0.03387*(TSS25)3 with r2 value 66% has been discovered from days taken for TSS25 (TSS of earliest 25% PP). Similarly, high r2 bearing polynomial equations were from days for anthesis and silking of the PPs of the fifteen hybrids. Equations with the lowest r2 were for the days required for the silk senescence (S SEN). Reason of low r2 is that the observation of silk browning or withering could not be precise for naked eye since the silks looked fresh longer in high humidity, low temperature and cloudy day in the winter although it lost receptivity earlier. In addition, Interval duration from S INI to S SEN cannot be the duration of silk receptivity in the winter of subtropical Nepalese Himalayan foot plain. For reproductive behavior; number of functional egg cells that became successful zygotes to pull assimilates for complete kernel development can reflect aroma about reproductive strength (RS) of the hybrid. Accordingly, hybrids 8 and 5 have been found of the highest RS.

scholarly journals Flowering, reproductive behaviors and their effects on grain yields of newly bred single cross hybrids of yellow maize (Zea mays L.) in winter in subtropical Nepalese Himalayan foot plain

2015 ◽  
Author(s):  
Nav Raj Adhikari ◽  
Surya Kant Ghimire ◽  
Shrawan Kumar Sah ◽  
Keshab Babu Koirala
Keyword(s):  
Coming Out ◽  
Reproductive Behavior ◽  
Polynomial Regression ◽  
Regression Equations ◽  
Reproductive Behaviors ◽  
Stressful Environment ◽  
Maize Population ◽  
Single Cross ◽  
Kernel Set ◽  
Single Cross Hybrids

Introduction: All the plants of a maize population or hybrid PP (plant population) do not dehisce anthers and do not emerge silk simultaneously. Generally, male flowering or anther dehiscence (anthesis) is leading and female flowering (silk emergence or silking) is lagging under both optimum and stressful environment. Enough and timely pollen availability is indispensable when silks come out of maize ears for largest number of kernel set. So; study of flowering and reproductive behavior of newly bred maize hybrids are indispensable to confirm high grain yielding hybrid with traits of synchrony in anthesis and silking, coming out of all silks and enough pollen availability in short duration. Materials and methods: Flowering and reproductive behaviors of fifteen newly bred single cross hybrids of yellow maize have been examined growing them in an RCBD trial planting their seeds on October 3, 2012 to expose flowering to the natural winter in subtropical foot plain of Himalaya. For flowering behavior; emergence of tassel, anthesis, silking, silk senescence, tassel-anthesis interval, anthesis-silking interval, silking-silk senescence interval of the hybrids have been examined dissecting the PP into four equal parts (percent) as the first earliest, second earliest, third earliest and terminal 25% of the hybrid PP denominated as 25, 50, 75 and 100% respectively of the each of the fifteen hybrids. So, whether third earliest 25% and terminal 25% silk emerging PP of each of the hybrids (SILK75 and SILK100%) respectively received enough pollen from the PP of the same hybrid can be determined through ASI 75 and ASI 100 of the hybrid PP. Results and discussion: Among some polynomial regression equations (PREs) discovered based on floral traits, a grain yield estimating PRE (t ha-1) Y = - 11922 + 507.3*(TSS25)1 - 7.183*(TSS25)2 + 0.03387*(TSS25)3 with r2 value 66% has been discovered from days taken for TSS25. Similarly, high r2 bearing PREs were from days for anthesis and silking. PREs with the lowest r2 were for the days required for the silk senescence (S SEN). Reasons of the low r2 are: the observation of silk browning or withering could not be precise for naked eye since the silks looked fresh longer in high humidity, well-irrigated state, low temperature, low sun-shine and foggy or cloudy day although the silks lost receptivity earlier in the winter. In addition, interval duration from SILK INI to S SEN cannot be the duration of silk receptivity in the winter of subtropical Nepalese Himalayan foot plain. For reproductive behavior; number of functional egg cells that became successful zygotes to pull assimilates for complete kernel development can reflect aroma about reproductive strength (RS) of the hybrid. Accordingly, hybrids 8 and 5 have been found of the highest RS.

scholarly journals Flowering, reproductive behaviors and their effects on grain yields of newly bred single cross hybrids of yellow maize (Zea mays L.) in winter in subtropical Nepalese Himalayan foot plain

2015 ◽  
Author(s):  
Nav Raj Adhikari ◽  
Surya Kant Ghimire ◽  
Shrawan Kumar Sah ◽  
Keshab Babu Koirala
Keyword(s):  
Coming Out ◽  
Reproductive Behavior ◽  
Polynomial Regression ◽  
Regression Equations ◽  
Reproductive Behaviors ◽  
Stressful Environment ◽  
Maize Population ◽  
Single Cross ◽  
Kernel Set ◽  
Single Cross Hybrids

Introduction: All the plants of a maize population or hybrid PP (plant population) do not dehisce anthers and do not emerge silk simultaneously. Generally, male flowering or anther dehiscence (anthesis) is leading and female flowering (silk emergence or silking) is lagging under both optimum and stressful environment. Enough and timely pollen availability is indispensable when silks come out of maize ears for largest number of kernel set. So; study of flowering and reproductive behavior of newly bred maize hybrids are indispensable to confirm high grain yielding hybrid with traits of synchrony in anthesis and silking, coming out of all silks and enough pollen availability in short duration. Materials and methods: Flowering and reproductive behaviors of fifteen newly bred single cross hybrids of yellow maize have been examined growing them in an RCBD trial planting their seeds on October 3, 2012 to expose flowering to the natural winter in subtropical foot plain of Himalaya. For flowering behavior; emergence of tassel, anthesis, silking, silk senescence, tassel-anthesis interval, anthesis-silking interval, silking-silk senescence interval of the hybrids have been examined dissecting the PP into four equal parts (percent) as the first earliest, second earliest, third earliest and terminal 25% of the hybrid PP denominated as 25, 50, 75 and 100% respectively of the each of the fifteen hybrids. So, whether third earliest 25% and terminal 25% silk emerging PP of each of the hybrids (SILK75 and SILK100%) respectively received enough pollen from the PP of the same hybrid can be determined through ASI 75 and ASI 100 of the hybrid PP. Results and discussion: Among some polynomial regression equations (PREs) discovered based on floral traits, a grain yield estimating PRE (t ha-1) Y = - 11922 + 507.3*(TSS25)1 - 7.183*(TSS25)2 + 0.03387*(TSS25)3 with r2 value 66% has been discovered from days taken for TSS25. Similarly, high r2 bearing PREs were from days for anthesis and silking. PREs with the lowest r2 were for the days required for the silk senescence (S SEN). Reasons of the low r2 are: the observation of silk browning or withering could not be precise for naked eye since the silks looked fresh longer in high humidity, well-irrigated state, low temperature, low sun-shine and foggy or cloudy day although the silks lost receptivity earlier in the winter. In addition, interval duration from SILK INI to S SEN cannot be the duration of silk receptivity in the winter of subtropical Nepalese Himalayan foot plain. For reproductive behavior; number of functional egg cells that became successful zygotes to pull assimilates for complete kernel development can reflect aroma about reproductive strength (RS) of the hybrid. Accordingly, hybrids 8 and 5 have been found of the highest RS.

The effect of honeycomb selection for grain yield on a maize population

1996 ◽  
Vol 127 (2) ◽  
pp. 143-149 ◽  
Author(s):  
A. Sotiriou ◽  
M. Koutsika-Sotiriou ◽  
E. Gouli-Vavdinoudi
Keyword(s):  
Genetic Variation ◽  
Grain Yield ◽  
Source Population ◽  
Maize Population ◽  
Single Cross ◽  
Honeycomb Selection ◽  
Sib Families ◽  
Selection For ◽  
Deleterious Genes ◽  
Single Cross Hybrids

SUMMARYStarting with the F2 generation of a single-cross hybrid, a maize population was improved from cycle 0 (= F2) to cycle 4 by mass honeycomb selection and from cycle 5 to cycle 8 by pedigree honeycomb selection. Seven half-sib families were derived from cycle 8. The grain yield of these, their corresponding S1 lines, testcrosses with B73 and diallel crosses were studied. The results showed (i) that the seven half-sib families contained half the percentage of the load of deleterious genes present in the F2 generation, (ii) that four of them outyielded their corresponding single-cross hybrids, (iii) that they could constitute an open-pollinated variety, which could be used as a source population and (iv) that they revealed different patterns for general and specific combining ability. Honeycomb selection for grain yield was successful in favouring the existing additive genetic variation in the derived families.

Maize population hybrids: Successful genetic resources for breeding programs and potential alternatives to single-cross hybrids

2007 ◽  
Vol 55 (1) ◽  
pp. 27-36 ◽  
Author(s):  
M. Carena
Keyword(s):  
Genetic Resources ◽  
Germplasm Conservation ◽  
Breeding Programs ◽  
Public And Private ◽  
The Public ◽  
Maize Population ◽  
Cultivar Development ◽  
Single Cross ◽  
Successful Approach ◽  
Single Cross Hybrids

Conservation of maize ( Zea mays L.) genetic resources has been the emphasis of national and international institutions for the benefit of mankind. However, limited resources have been devoted to their adequate exploitation, making genetic resources less useful to the public and private scientific community. As a consequence, public maize breeders have exploited a limited number of heterotic combinations for cultivar development and basic molecular studies while genetic effects are different for different hybrids. Extensive testing of maize population hybrids is a successful approach to choose and improve germplasm sources with high mean performance, useful genetic variability, and excellent combining ability. There is a need to keep applied breeding programs strong in order to link efforts in germplasm conservation with its improvement and utilization.

scholarly journals Stability Assessment of Single-Cross Maize Hybrids Using GGE-Biplot Analysis

2021 ◽  
Vol 13 (2) ◽  
pp. 78
Author(s):  
L. Musundire ◽  
J. Derera ◽  
S. Dari ◽  
A. Lagat ◽  
P. Tongoona
Keyword(s):  
Grain Yield ◽  
South African ◽  
Inbred Line ◽  
Inbred Lines ◽  
Yield Potential ◽  
Research Station ◽  
Gge Biplot ◽  
Single Cross ◽  
Ideal Genotype ◽  
Single Cross Hybrids

Grain yield potential of new maize hybrid varieties across target environments contributes to the uptake of these varieties by farmers. Evaluation of single-cross hybrids developed from test crossing introgressed inbred lines bred for three distinct environments to elite tropical inbred line testers was carried out. The study’s objective was to assess grain yield stability and genotype adaptability of the single-cross hybrids across South African environments relative to adapted commercial hybrid checks. One hundred and twenty-two introgressed inbred lines developed using the pedigree breeding program were crossed to four tropical elite inbred line testers using line × tester mating design to obtain 488 experimental single cross hybrids. Subject to availability of adequate seed for evaluation, a panel of 444 experimental single-cross hybrids was evaluated using an augmented design in two experiments defined as Population A and B for the study’s convenience in South African environments. Data for grain yield (t/ha) performance for experimental single-cross hybrids and commercial check hybrids in Population A and B across environments and individual environments identified experimental single-cross hybrids that had significant comparable grain yield (t/ha) performance relative to best commercial check hybrid (PAN6Q445B) on the market. The selected experimental single-cross hybrids 225, 89, 246 and 43 (Population A) and 112 (Population B) also had a better average rank position for grain yield (t/ha) relative to best commercial check hybrid. These selected experimental single-cross hybrids had a grain yield (t/ha) advantage range of 0.9-6.7% for Population A and 7.3% for Population A and B, respectively, relative to the adapted commercial check hybrid. GGE biplot patterns for which won-where for Population A indicated that at Potchefstroom Research Station and Ukulinga Research Station experimental single-cross hybrids 127 and135 were the vertex (winning) hybrids. Cedera Research Station did not have a vertex hybrid for Population A. For Population B, experimental single-cross hybrids 112, 117 and 18 were the vertex hybrids at Cedera Research Station, Ukulinga Research Station and Potchefstroom Research Station, respectively. Experimental single-cross hybrid 257 was identified as ideal genotype for Population A, while experimental single-cross hybrid 121 in Population B was the ideal genotype. Ideal environments were also identified as Ukulinga Research Station for Population A, and Cedera Research Station for Population B. Average-environment coordination (AEC) view of the GGE biplot in Population A indicated that experimental single-cross hybrids 1 was highly stable across environments. In comparison, Population B experimental single-cross hybrid 161 was highly stable across environments. In conclusion, selected single-cross hybrids in the current study can also be advanced for further evaluation with a possibility for identifying high yielding and stable single-cross hybrids for variety registration and release in target environments in South Africa.

RESISTANCE OF INBRED LINES AND HYBRIDS OF SUNFLOWERS (HELIANTHUS ANNUUS L.) IN A NATURAL EPIDEMIC OF ASTER YELLOWS

1960 ◽  
Vol 40 (2) ◽  
pp. 375-382 ◽  
Author(s):  
Eric D. Putt ◽  
W. E. Sackston
Keyword(s):  
Helianthus Annuus ◽  
Inbred Lines ◽  
Field Conditions ◽  
Single Plant ◽  
Aster Yellows ◽  
Helianthus Annuus L ◽  
Single Cross ◽  
Single Cross Hybrids

Resistance to aster yellows has been identified in sunflowers. In 560 inbred lines and single plant progenies, 356 showed no symptoms of the disease under field conditions. The others showed infections ranging up to 100 per cent. Six entries, observed at three points, showed a range of infection from 0 to 86 per cent and eighteen others, at two points, a range from 0 to 73 per cent. The behaviour was consistent at the different locations.The resistance to aster yellows appeared to be qualitatively inherited. Single cross hybrids between resistant and, susceptible lines showed the resistance to be dominant. It occurred in association both with susceptibility and with resistance to rust. Of 15 lines with evidence of resistance to leaf mottle disease, 13 lines also had resistance to aster yellows.

Assessment of tomato source breeding material through mating designs

2007 ◽  
Vol 146 (3) ◽  
pp. 301-310 ◽  
Author(s):  
M. S. KOUTSIKA-SOTIRIOU ◽  
E. A. TRAKA-MAVRONA ◽  
G. L. EVGENIDIS
Keyword(s):  
Combining Ability ◽  
Source Material ◽  
Plant Performance ◽  
Breeding Value ◽  
Population Bottlenecks ◽  
Plant Selection ◽  
Single Cross ◽  
High Yielding Varieties ◽  
Founder Events ◽  
Single Cross Hybrids

SUMMARYCultivated tomato has a narrow germplasm base because of several population bottlenecks in the form of founder events, as well as natural and artificial selections that occurred during domestication and evolution of modern cultivars. The F2 of commercial single-cross hybrids, as well as locally well-adapted varieties, provide germplasm for developing recombinant lines and exploiting genetic variability, respectively. The present study aims to discriminate the breeding value of tomato source material, i.e. commercial hybrids or well-adapted varieties, by (i) estimating tolerance to inbreeding of hybrids or estimating heterosis of diallel hybrids between varieties, (ii) determining undesirable traits and (iii) determining general combining ability (GCA) and specific combining ability (SCA) effects from diallel crosses between hybrids and between varieties. Two hybrids and four varieties were assessed. One hybrid showed 0·03 inbreeding vigour, which was not combined with undesirable traits in the F2 generation. However, negative GCA and positive SCA values did not support the hybrid as source material, provided that hybrids with low inbreeding depression, positive GCA and negative SCA correspond to an F2 capable of developing recombinant lines. The assessment of the varieties showed positive GCA and 0·34 heterosis in one variety, indicating agreement between yield and GCA, and that high-yielding varieties may produce high-yielding hybrids. In conclusion, the proposed mating design, taking into account the tolerance to inbreeding for hybrids and the heritability of general worth for both resources, provides a mechanism for ensuring continued improvement in plant performance through plant selection programmes.

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