INFLUENCE OF PLANT DENSITY ON THE DISTRIBUTION OF 14C-LABELLED ASSIMILATE IN MAIZE AT FLOWERING

1979 ◽  
Vol 59 (3) ◽  
pp. 577-584 ◽  
Author(s):  
G. O. EDMEADES ◽  
N. A. FAIREY ◽  
T. B. DAYNARD
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Plant Density ◽  
Reproductive Organs ◽  
Planting Density ◽  
Dominant Factor ◽  
Vegetative Organs ◽  
Coefficients Of Variation ◽  
Plant Densities ◽  
Lower Stem

The distribution pattern of 14C-labelled assimilate in the flowering shoot of maize (Zea mays L.) grown in the field at three plant densities (50 000, 100 000 and 150 000 plants/ha) was determined by labelling with 14CO2 at 1 day after anthesis. Shoots were harvested 4 days later. Four leaf positions were fed 14CO2 at each density; relative to the ear leaf (EL), these were EL+4 (i.e. fourth leaf above ear leaf), EL+2, EL, and EL-2. At the lowest plant density EL-4 was also labelled. The dominant factor influencing assimilate distribution was the position of the assimilating leaf rather than plant density. Assimilate from upper leaves supplied the tassel, upper stem, and ear preferentially. Assimilate from lower leaves supplied the lower stem and ear. Among leaf positions the ear leaf supplied the greatest percentage of its assimilate (26% at 50 000 plants/ha and 19% at 150 000 plants/ha) to the developing cob (rachis plus grain initials). As density increased so did the proportion of labelled assimilate remaining in labelled leaves. Coefficients of variation, computed among individual plants, indicated that assimilate distribution to reproductive organs was more variable than that to vegetative organs and that this variability increased with planting density.

scholarly journals DNA METHYLATION AND FESOD GENE EXPRESSION AFFECTED BY PLANT DENSITY IN ZEA MAYS L.

2019 ◽  
Vol 50 (Special) ◽  
Author(s):  
Shenawa & Alfalahi
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Zea Mays ◽  
Zea Mays L ◽  
Plant Density ◽  
Maximum Level ◽  
Planting Density ◽  
Gene Copies ◽  
High Plant Density ◽  
Different Response

Methylation Sensitive Amplification Polymorphism (MSAP) was used to characterize the alterations in DNA methylation in maize (Zea mays L.) inbred lines and their half-daillels affected by plant densities (213333 plant h-1 and 13333 plant h-1). The two restriction was enzymes ( HpaII and MspI) succeeded in diagnosing a total of 23 specific loci, most of (22 loci) were Methylation Sensitive Loci (MSL), while the only one NML (No Methylated Loci) was monomorphic. Thirteen out of 22 MSL loci polymorphic, recording a were polymorphism percentage of 59%. Results of FeSOD gene expression cleared the different response of maize inbreds and hybrids to high plant density stress. Generally, the expression of  the targeted gene was increased in plants submitted to high plant density stress compared with low density. The inbred 3 and its single hybrid 1×3 achieved the highest level of gene expression under high planting density (5505.7 and 21098.6 copy, respectively), meanwhile, inbred 5 and it's single hybrid 4×5 gained the maximum level of FeSOD expression at the low plant density (8317.6 and 6862.1 copy, respectively). The response reached to its maximum limit in many of those genotypes, some other genotypes showed relatively steady performance along with higher stress, such as parent 1, that gave the lowest number of gene copies in both, high and low plant density (1375.8 and 1569.5 copy, respectively).

scholarly journals Changes in plant density dependence of leaf photosynthesis of maize (Zea mays L.) hybrids, 1959 to 1988

1991 ◽  
Vol 71 (1) ◽  
pp. 1-11 ◽  
Author(s):  
L. M. Dwyer ◽  
D. W. Stewart ◽  
M. Tollenaar
Keyword(s):  
Zea Mays ◽  
Grain Yield ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Zea Mays L ◽  
Plant Density ◽  
Leaf Photosynthesis ◽  
Area Index ◽  
Photosynthetic Rates ◽  
Plant Densities

Understanding of the physiological basis for increased maize (Zea mays L.) yields over the last three decades may contribute to future genetic improvement. Recent maize production systems have tended to increase plant densities to maximize grain yield. The objective of this field study was to determine if there were changes in the response of leaf photosynthetic rates to increasing plant densities in four hybrids grown in Ontario from 1959 to 1989. The four hybrids, numbered from the oldest to most recent hybrid ((1) Pride 5, (2) United 106, (3) Pioneer 3978 and (4) Pioneer 3902) were grown at 20 000, 80 000 and 130 000 plants ha−1. Leaf photosynthetic response to irradiance (PRI) and crop growth rate (CGR) were measured near silking and during late grainfilling, leaf area index (LAI) was measured near silking and total grain yield was measured after maturity. The LAIs of recent hybrids tended to be larger than for old hybrids at comparable plant densities. Leaf photosynthetic rates declined in all hybrids at increasing densities, but the decline occurred at lower LAIs in the older hybrids. As a result, despite the higher LAIs of recent hybrids, they showed an equal or higher PRI at all plant densities. The higher PRI of recent hybrids was correlated with higher CGRs and grain yields. These results suggest that increases in optimum plant density for grain and increases in yield may be attributable, in part, to higher PRI at elevated LAIs in recent hybrids. Key words: Leaf area index, plant density, leaf photosynthesis, Zea mays L.

GRAIN YIELD COMPARISON OF PURE STANDS AND MIXTURES OF DIFFERENT PROPORTIONS FOR TWO HYBRIDS OF MAIZE

1985 ◽  
Vol 65 (3) ◽  
pp. 481-485 ◽  
Author(s):  
G. J. HOEKSTRA ◽  
L. W. KANNENBERG ◽  
B. R. CHRISTIE
Keyword(s):  
Zea Mays ◽  
Grain Yield ◽  
Zea Mays L ◽  
Pure Stand ◽  
Higher Plant ◽  
Data Support ◽  
Plant Densities ◽  
The Difference ◽  
Corn Grain ◽  
Corn Grain Yield

The objective of this study was to determine the effects on grain yield of growing cultivars in mixtures of different proportions. Two maize (Zea mays L.) hybrids, Pride 116 and United 106, were grown for 2 yr in pure stand and in seven mixtures of different proportions (7:1, 6:2, 5:3, 4:4, 3:5, 2:6, 1:7) at plant densities of 61 500, 99 400, and 136 000 plants per hectare. The total number of mixture combinations was 42, i.e. 2 years × three densities × seven proportions. All but one mixture yielded as expected based on the yield of component hybrids in pure stand. The higher yielding hybrid (United 106) yielded significantly less grain per plant in mixtures than in pure stand. The lower yielding hybrid (Pride 116) yielded more in mixtures than in pure stand, although the difference was not significant. These data support previous observations that the ability of a hybrid to yield in pure stands is not necessarily related to its ability to yield in mixtures. High plant densities appear to enhance the likelihood of interactions occurring among hybrids. For United 106, the number of proportions yielding less grain per plant than in pure stand was highly significant at the two higher plant densities. For Pride 116, the number of proportions yielding more than in pure stand was highly significant at the highest plant density.Key words: Corn, grain yield, mixtures of different proportions, high plant densities, Zea mays

scholarly journals Genetic Variability of Maize (Zea mays L.) Genotypes on Some Yield and Yield Components at Haramaya, Eastern Ethiopia

2020 ◽  
Vol 8 (9) ◽  
pp. 1840-1845
Author(s):  
Mekuannet Belay Kebede ◽  
Degefa Gebissa
Keyword(s):  
Zea Mays ◽  
Genetic Variability ◽  
Zea Mays L ◽  
Genotype 1 ◽  
Eastern Ethiopia ◽  
Maize Production ◽  
Maize Genotypes ◽  
Coefficients Of Variation ◽  
Study Results ◽  
Almost All

Genetic improvement in components of economic importance along with maintaining a sufficient amount of variability is always the desired objective in the any maize (Zea mays L.) breeding program which will be handled under the conditions of Haramaya, Eastern Ethiopia. Therefore, an experiment was conducted using (27) and (3) check/control varieties to determine the genetic variability of maize genotypes at Haramaya, eastern Ethiopia. The study results revealed that significantly the tallest plant heights for (PH) were recorded from (3) (170 cm) and (18) (167.5 cm) genotypes whereas the shortest PH were recorded from (13) (117.5 cm) and (23) genotypes (120 cm). Good plant aspects (PA) were obtained from genotype 12, 22 and 26 (PA-1.5) and poor PA were attained from genotype 1 (PA-2.5). Besides, genetic and phenotypic variances were estimated for seven components. The highest genotypic coefficients variation (GCV) and phenotypic coefficients of variation (PCV) were calculated from grain yield (GY – 23.39%). Comparatively the higher GY were attained from the genotypes of 3, 9 and 12. It can be concluded that almost all components of the PCV are greater than the GCV. Superior selected genotypes are recommended to the researchers /breeders to develop disease resistant and high yielder varieties to increase maize production by farmers under Haramaya and other similar agroecologies.

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