Changes in physiological traits associated with grain yield improvement in single-cross maize hybrids from 1930 to 1970

1983 ◽  
Author(s):  
Diane Currie Tapper
Keyword(s):  
Grain Yield ◽  
Physiological Traits ◽  
Yield Improvement ◽  
Maize Hybrids ◽  
Single Cross

Bromoxynil tolerance during the seedling phase is associated with genetic grain yield improvement in maize

1991 ◽  
Vol 71 (4) ◽  
pp. 1021-1027 ◽  
Author(s):  
M. Tollenaar ◽  
M. Mihajlovic
Keyword(s):  
Zea Mays ◽  
Chlorophyll Fluorescence ◽  
Grain Yield ◽  
Stress Tolerance ◽  
Field Experiments ◽  
Zea Mays L ◽  
Environmental Stresses ◽  
Yield Improvement ◽  
Maize Hybrids ◽  
Highly Correlated

Genetic grain yield improvement of maize (Zea mays L.) in Ontario during the past three decades can be attributed, in part, to increased tolerance to environmental stresses. We have observed a differential response of field-grown old and new hybrids after application of the photosystem II inhibiting herbicide bromoxynil (4-hydroxy-3,5-dibromobenzonitrile). Studies were conducted to test whether tolerance to bromoxynil is associated with stress tolerance and grain yield in maize hybrids representing three decades of yield improvement in Ontario. Experiments were carried out with seedlings of eight maize hybrids grown in pots in controlled-environment growth cabinets and, in one experiment, with seedlings grown in pots outside during the months of July and August at Guelph, Ontario. Bromoxynil was applied to the youngest fully-expanded leaf of plants at the 6- to 8-leaf stage and chlorophyll fluorescence of the treated leaves was measured in the 2- to 24-h period after bomoxynil application. Results showed that the chlorophyll fluorescence ratio Fv/Fm, an indicator of photosynthetic efficiency, declined after bromoxynil application until 4 h after application and, subsequently, recovered slightly during the next 20 h. Large differences in the Fv/Fm ratio were apparent among hybrids in the response to bromoxynil. The Fv/Fm ratio was significantly higher for hybrids released in the 1980s than for hybrids released in the 1970s, and the Fv/Fm ratio of the latter group was significantly higher than that of the four oldest hybrids. Chlorophyll fluorescence ratios Fv/Fm after bromoxynil application in the seedling phase were highly correlated with grain yield of the hybrids in field experiments conducted during 1987 and 1988 (r = 0.91). Results of this study support the contention that maize genotypes that are less sensitive to bromoxynil are less susceptible to environmental stresses. Key words: Zea mays L., stress tolerance, bromoxynil, chlorophyll fluorescence, Fv/Fm ratio, detoxifying agents

scholarly journals Dynamics of chlorophyll and N concentration on e0 and e3 leaves of maize hybrids in winter in subtropical region

2015 ◽  
Author(s):  
Nav Raj Adhikari ◽  
Surya Kant Ghimire ◽  
Shrawan Kumar Sah ◽  
Keshab Babu Koirala
Keyword(s):  
Grain Yield ◽  
Soluble Protein ◽  
Red Light ◽  
Grain Filling ◽  
Soluble Proteins ◽  
Subtropical Region ◽  
Maize Hybrids ◽  
N Concentration ◽  
Single Cross ◽  
Grain Filling Duration

National maize productivity is very low in Nepal. Increase of the productivity is only possible through growing high grain yielding single cross hybrid maize cultivar. So, development and evaluation of maize hybrids are principal steps to select high grain yielding and superior hybrid for cultivar. For it, fifteen newly bred single cross hybrids of yellow maize were examined from the standpoint of chlorophyll (chl) dynamics and their effects on grain yield. For it, a trial of RCBD experiment was conducted in open field in winter in subtropical region in Nepal. Seeds were sown on October 3, 2012 plot in two row plot area of 1.4 x 3.0 m2. After anthesis, chl and N concentration (conc) implying RAT (red light absorbance-transmittance) SPAD measure were taken from the topmost ear (e0) and third (e3) leaf above the e0 in ten days interval during grain filling. SPAD measures were transformed to total chl and N conc. E0 leaf has been found more grain yield determining than e3 leaf and terminal grain filling duration has been found more determining than early grain filling from the standpoint of correlation of grain yield with chl, N conc and SPAD measure. From pooled variance analysis; SPAD and chl conc were not significant different in different leaves and among the hybrids (Hybrids x Leaves x Ages). But, the SPAD and chl conc were significant different among the two leaves and ages (Leaves x Ages) irrespective of the hybrids. Different to the SPAD and chl conc, N conc was significant different in the leaves among the hybrids with respect to ages of the plants among the hybrids (Hybrids x Leaves x Ages). Thirteen top high grain yielding hybrids (HGYHs) 8, 12, 11, 13, 5, 6, 10, 1, 7, 14, 2, 9 and 15 were non-significant different from the standpoint of grain yield. The SPADs were in the non-significant range of 51-55 in e0 leaf in the duration from 95 to 125 d among the fifteen hybrids. Among the top four HGYHs 8, 12, 11 and 13; hybrid 11 lost chl and N from e0 leaf significantly on 135th d relative to the most of the hybrids. It means that the hybrid 11 could efficiently degrade N containing soluble protein and chl even from e0 leaf relatively. Top five HGYHS 8, 12, 11, 5 and 6 except 13 among the top listed ten hybrids constantly maintained chl and N conc implying SPAD in the e0 leaf up to the 135th d. In addition, it implies that these five hybrids sent newly up-taken N to kernels without degradation of the proteins and chl from the e0 leaf till the age of 135 d. HGYH 8 had degraded soluble proteins and enzymes and chl in e3 leaf and mobilized the degraded N to the kernels more efficiently from the e3 leaf. It is not necessary that maize hybrids must constantly maintain soluble proteins and chl conc during most of early to mid-grain filling duration for high grain yield. Instead, efficient reasonable decline of the soluble protein and chl conc during early to mid-grain filling also accelerate grain filling phenomena.

scholarly journals Studies on Photosynthetic Rate, Anatomical Characters, and Grain Yield in Finger Millet Genotypes

2020 ◽  
pp. 31-39
Author(s):  
Y. A. Nanja Reddy
Keyword(s):  
Grain Yield ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Finger Millet ◽  
Management Practices ◽  
Physiological Traits ◽  
Yield Improvement ◽  
Yield Attributes ◽  
Net Assimilation ◽  
Millet Yield

Finger millet (Eleusine coracana L. Gaertn.) yield improvement has been achieved through development of blast resistant varieties and adoption of appropriate management practices. However, yield improvement is approaching stagnation and further improvement could be possible by inclusion of physiological traits in addition to yield per se. In this direction, nine selected genotypes for high net assimilation were compared with popular Cv. GPU-28 for photosynthetic, anatomical, and yield contributing traits to identify a better genotype and physiological traits associated with grain yield. Results revealed that the photosynthetic rate did not differ significantly between genotypes, but influenced the grain yield through increased earhead size and harvest index. Path analysis showed a direct positive effect of photosynthetic rate, transpiration rate, mean earhead size and productive tillers towards grain yield. The photosynthetic rate was positively associated with leaf lamina thickness and vein frequency. Therefore, for finger millet yield improvement, traits like photosynthetic rate/ transpiration rate and mean earhead size with 3 to 4 tillers could be selected. Variety, GPU-28 which is widely cultivated had better photosynthetic traits and grain yield attributes, this variety can be used as important baseline check for both photosynthetic rate and grain yield in finger millet yield improvement programmes.

scholarly journals Evaluation of single-cross maize hybrids for flowering and grain yield traits

2020 ◽  
pp. 1
Author(s):  
Susmita Kafle ◽  
Nav Adhikari ◽  
Subarna Sharma ◽  
Jiban Shrestha
Keyword(s):  
Grain Yield ◽  
Yield Traits ◽  
Maize Hybrids ◽  
Single Cross

scholarly journals Nitrogen Management Studies in Maize (Zea Mays L.) Hybrids

2013 ◽  
Vol 46 (3) ◽  
pp. 39-48 ◽  
Author(s):  
S. Iqbal ◽  
H.Z. Khan ◽  
N. Akbar ◽  
M.S.I. Zamir ◽  
H.M.R. Javeed ◽  
...  
Keyword(s):  
Grain Yield ◽  
Plant Height ◽  
Seed Oil ◽  
Seed Protein ◽  
Foliar Application ◽  
Nitrogen Management ◽  
Maize Hybrids ◽  
Knee Height ◽  
Single Cross ◽  
Biological Yield

Abstract A field experiment was conducted to study the effect of different nitrogen management methods on yield, yield components and quality attributes of maize hybrids (single cross-6142 and double cross-4444) under irrigated conditions. Nitrogen dose is met either by PM (poultry manure) or urea according to each treatment. PM was incorporated at the time of presowing irrigation whereas fertigation method at knee height stage and foliar spray at flowering were use for the application of urea. Results showed that plant height, cob diameter, number of grains per cob, grain yield and biological yield were significantly affected by the hybrids. Significantly, higher plant height, cob diameter, number of grains per cob, grain yield and biological yield were produced by single cross-6142. There was no significant difference occur between both hybrids on seed oil and protein contents. N management by the application of T3 (60% N from PM + 38.5% N from urea through fertigation + 1.5% N from urea through foliar application) produced significantly more plant height, cob diameter, number of grains per cob, grain yield, biological yield, seed protein and seed oil contents. The interaction of single cross-6142 and T3 (60% N from PM + 38.5% N from urea through fertigation + 1.5% N from urea through foliar application) was found superior in production of more plant height, cob diameter and number of grains per cob. However, interaction between maize hybrids and N application methods for grain yield, biological yield, seed protein and oil contents was reported nonsignificant. It can be concluded that single cross hybrid-6142) and T3 (60% N from PM, 38.5% N from urea through fertigation and 1.5% N from urea through foliar application) could be used successfully for improving maize yield under the irrigated conditions.

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