EFFECTS OF REDUCING INTERPLANT COMPETITION AT DIFFERENT STAGES OF GROWTH ON STALK ROT AND YIELD COMPONENTS OF CORN

1969 ◽  
Vol 49 (6) ◽  
pp. 723-729 ◽  
Author(s):  
C. G. Mortimore ◽  
L. F. Gates

Stress effects on stalk rot and yield components of corn (Zea mays L.), arising from interplant competition, were, studied by removing at various times either the competing plants or the developing ears. The number of ears per plant and the number of kernels per ear at harvest were greater when plants were thinned before mid-silk, but the only yield component associated with stalk rot was 1000-kernel weight.Removal of alternate plants at any time up to 4 weeks after mid-silk greatly reduced the proportion of plants developing stalk rot. In plots thinned less than 4 weeks before physiological maturity, the incidence of stalk rot increased progressively as thinning was delayed. Similarly, up to 1 month before physiological maturity, stress had little effect on weight of individual kernels but when the stress was continued into the month which preceded physiological maturity, individual kernel weights were substantially decreased. Ear removal 3 weeks or more before maturity practically eliminated stalk rot whereas later removal had progressively less effect. Thus, the deleterious effects of stress from interplant competition and ear development had their maximum effect on stalk rot susceptibility and kernel weight during the month before physiological maturity.

2004 ◽  
Vol 84 (4) ◽  
pp. 1025-1036 ◽  
Author(s):  
William E. May ◽  
Ramona M. Mohr ◽  
Guy P. Lafond ◽  
Adrian M. Johnston ◽  
F. Craig Stevenson

The proportion of oat (Avena sativa L.) being used for race horses and human consumption has increased over the past 15 yr. The objective of this study was to evaluate the effects of N, seeding date and cultivar on grain yield components, grain yield and grain quality of oat under a direct seeding system. Four N rates, three seeding dates and two cultivars were tested at Indian Head, Melfort, and Canora, SK, and Brandon, MB. Yield was more responsive to increasing N rates from 15 and 80 kg ha-1 when oat was seeded in early May versus early June. Panicles plant-1 was the yield component that accounted for most of the yield increase achieved from increasing rates of N, while kernel weight was the yield component that decreased as the rate of N increased. Physical seed quality decreased (plump seed decreased and thin seed increased) with delayed seeding and greater N fertilizer rates. Nitrogen fertilizer and seeding date had a much larger effect on the quality of CDC Pacer than AC Assiniboia. Combining early seeding, appropriate N fertility and well-adapted cultivars should increase the likelihood of optimizing oat yield and quality necessary for high-value markets. Key words: Avena sativa L., yield components, test weight, lodging, plump seed, thin seed


Author(s):  
Kyle Isham ◽  
Rui Wang ◽  
Weidong Zhao ◽  
Justin Wheeler ◽  
Natalie Klassen ◽  
...  

Abstract Key message Four genomic regions on chromosomes 4A, 6A, 7B, and 7D were discovered, each with multiple tightly linked QTL (QTL clusters) associated with two to three yield components. The 7D QTL cluster was associated with grain yield, fertile spikelet number per spike, thousand kernel weight, and heading date. It was located in the flanking region of FT-D1, a homolog gene of Arabidopsis FLOWERING LOCUS T, a major gene that regulates wheat flowering. Abstract Genetic manipulation of yield components is an important approach to increase grain yield in wheat (Triticum aestivum). The present study used a mapping population comprised of 181 doubled haploid lines derived from two high-yielding spring wheat cultivars, UI Platinum and LCS Star. The two cultivars and the derived population were assessed for six traits in eight field trials primarily in Idaho in the USA. The six traits were grain yield, fertile spikelet number per spike, productive tiller number per unit area, thousand kernel weight, heading date, and plant height. Quantitative Trait Locus (QTL) analysis of the six traits was conducted using 14,236 single-nucleotide polymorphism (SNP) markers generated from the wheat 90 K SNP and the exome and promoter capture arrays. Of the 19 QTL detected, 14 were clustered in four chromosomal regions on 4A, 6A, 7B and 7D. Each of the four QTL clusters was associated with multiple yield component traits, and these traits were often negatively correlated with one another. As a result, additional QTL dissection studies are needed to optimize trade-offs among yield component traits for specific production environments. Kompetitive allele-specific PCR markers for the four QTL clusters were developed and assessed in an elite spring wheat panel of 170 lines, and eight of the 14 QTL were validated. The two parents contain complementary alleles for the four QTL clusters, suggesting the possibility of improving grain yield via genetic recombination of yield component loci.


1997 ◽  
Vol 129 (1) ◽  
pp. 13-18 ◽  
Author(s):  
S. S. HUNDAL ◽  
PRABHJYOT-KAUR

The crop–environment resource synthesis model for wheat, CERES–Wheat, was used to simulate yields from 1985 to 1993 at Ludhiana, India. The simulated anthesis and physiological maturity dates, grain and total biomass yields of wheat were compared with actual observations for the commonly grown cultivar, HD–2329. The simulated and actual dates of phenological events showed deviations from only −9 to +6 days for anthesis and −6 to +3 days for physiological maturity of the crop. The model estimated the kernel weight within 88–113% (mean 100%) of the actual kernel weights. The model predicted the grain yields from 80 to 115% (mean 97·5%) of the observed grain yield. Biomass yields were predicted from 93 to 128% (mean 110·5%) of the observed yields. The results obtained with the model for the eight crop seasons demonstrated satisfactory predictions of phenology, growth and yield of wheat. However, the biomass simulations indicated the need for further examination of the factors controlling the partitioning of photosynthates during crop growth. The results of this study reveal that the calibrated CERES–Wheat model can be used for the prediction of wheat growth and yield in the central irrigated plains of the Indian Punjab.


1992 ◽  
Vol 72 (3) ◽  
pp. 663-669 ◽  
Author(s):  
S. M. Dofing ◽  
C. W. Knight ◽  
T. G. Berke ◽  
P. S. Baenziger

Plant breeders are continually searching for new sources of genetically diverse germplasm from which superior genotypes might be developed. The objective of this study was to assess the performance of subarctic- and temperate-adapted barley cultivars when grown in reciprocal areas of adaptation to determine their potential for use in breeding programs. Four subarctic-adapted and four temperature-adapted barley (Hordeum vulgare L.) cultivars were grown at two environments each in Alaska (subarctic) and Nebraska (temperate) for 2 yr. Subarctic-adapted cultivars were earlier heading and earlier maturing in both environments, although differences were larger in subarctic environments. Grain yield of the two classes of cultivars was similar in subarctic environments, but temperate-adapted cultivars were far superior when grown intemperate environments. Kernel weight of all cultivars was higher in subarctic environments than in temperate environments. Maturity differences alone did not account for the poor performance of subarctic-adapted cultivars in temperate environments. Yield was positively correlated with all three yield components in temperate environments, but only with spikes per square meter in subarctic environments. Results from this study suggest that greater potential exists for the utilization of temperate-adapted germplasm to favourably increase the genetic diversity of subarctic-adapted germplasm than vice versa.Key words: Barley, Hordeum vulgare L., adaptation, yield components


2022 ◽  
Vol 12 ◽  
Author(s):  
Federico H. Larrosa ◽  
Lucas Borrás

Altered stand density affects maize yields by producing changes in both numerical yield components, kernel number per plant (KNP), and kernel weight (KW). Kernel number is determined by the accumulation of ear biomass during the flowering period, whereas KW is determined by the sink potential established during flowering and the capacity of the plant to fulfill this potential during effective grain filling. Here, we tested if different short shading treatments during different stages around flowering can help discriminate genotypic differences in eco-physiological parameters relevant for maize stand density yield response and associated yield components. Our specific objectives were to: (i) identify hybrids with differential shading stress response, (ii) explore shading effects over eco-physiological parameters mechanistically related to KNP and KW, and (iii) test if shading stress can be used for detecting differential genotypic yield responses to stand density. The objectives were tested using four commercial maize hybrids. Results indicated that KNP was the yield component most related to yield changes across the different shading treatments, and that the specific shading imposed soon after anthesis generated the highest yield reductions. Hybrids less sensitive to shading stress were those that reduced their plant growth rate the least and the ones that accumulated more ear biomass during flowering. Genotype susceptibility to shading stress around flowering was correlated to stand density responses. This indicated that specific shading stress treatments are a useful tool to phenotype for differential stand density responses of commercial hybrids.


2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Zoltán Áy ◽  
Róbert Mihály ◽  
Mátyás Cserháti ◽  
Éva Kótai ◽  
János Pauk

We present an experiment done on abar+wheat line treated with 14 different concentrations of glufosinate ammonium—an effective component of nonselective herbicides—during seed germination in a closed experimental system. Yield components as number of spikes per plant, number of grains per spike, thousand kernel weight, and yield per plant were thoroughly analysed and statistically evaluated after harvesting. We found that a concentration of glufosinate ammonium 5000 times the lethal dose was not enough to inhibit the germination of transgenic plants expressing thebargene. Extremely high concentrations of glufosinate ammonium caused a bushy phenotype, significantly lower numbers of grains per spike, and thousand kernel weights. Concerning the productivity, we observed that concentrations of glufosinate ammonium 64 times the lethal dose did not lead to yield depression. Our results draw attention to the possibilities implied in the transgenic approaches.


Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1240
Author(s):  
Peder K. Schmitz ◽  
Joel K. Ransom

Agronomic practices, such as planting date, seeding rate, and genotype, commonly influence hard red spring wheat (HRSW, Triticum aestivum L. emend. Thell.) production. Determining the agronomic optimum seeding rate (AOSR) of newly developed hybrids is needed as they respond to seeding rates differently from inbred cultivars. The objectives of this research were to determine the AOSR of new HRSW hybrids, how seeding rate alters their various yield components, and whether hybrids offer increased end-use quality, compared to conventional cultivars. The performance of two cultivars (inbreds) and five hybrids was evaluated in nine North Dakota environments at five seeding rates in 2019−2020. Responses to seeding rate for yield and protein yield differed among the genotypes. The AOSR ranged from 3.60 to 5.19 million seeds ha−1 and 2.22 to 3.89 million seeds ha−1 for yield and protein yield, respectively. The average AOSR for yield for the hybrids was similar to that of conventional cultivars. However, the maximum protein yield of the hybrids was achieved at 0.50 million seeds ha−1 less than that of the cultivars tested. The yield component that explained the greatest proportion of differences in yield as seeding rates varied was kernels spike−1 (r = 0.17 to 0.43). The end-use quality of the hybrids tested was not superior to that of the conventional cultivars, indicating that yield will likely be the determinant of the economic feasibility of any future released hybrids.


Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 466
Author(s):  
Qibo Tao ◽  
Mengjie Bai ◽  
Cunzhi Jia ◽  
Yunhua Han ◽  
Yanrong Wang

Irrigation and nitrogen (N) are two crucial factors affecting perennial grass seed production. To investigate the effects of irrigation and N rate on seed yield (SY), yield components, and water use efficiency (WUE) of Cleistogenes songorica (Roshevitz) Ohwi, an ecologically significant perennial grass, a four-year (2016–2019) field trial was conducted in an arid region of northwestern China. Two irrigation regimes (I1 treatment: irrigation at tillering stage; I2 treatment: irrigation at tillering, spikelet initiation, and early flowering stages) and four N rates (0, 60, 120, 180 kg ha−1) were arranged. Increasing amounts of both irrigation and N improved SY, evapotranspiration, WUE, and related yield components like fertile tillers m−2 (FTSM) and seeds spikelet−1. Meanwhile, no significant difference was observed between 120 and 180 kg N ha−1 treatments for most variables. The highest SY and WUE was obtained with treatment combination of I2 plus 120 kg N ha−1 with four-year average values of 507.3 kg ha−1 and 1.8 kg ha−1 mm−1, respectively. Path coefficient and contribution analysis indicated that FTSM was the most important yield component for SY, with direct path coefficient and contribution coefficient of 0.626 and 0.592. Overall, we recommend I2 treatment (three irrigations) together with 120 kg N ha−1 to both increase SY and WUE, especially in arid regions. Future agronomic managements and breeding programs for seed should mainly focus on FTSM. This study will enable grass seed producers, plant breeders, and government program directors to more effectively target higher SY of C. songorica.


Genetics ◽  
1997 ◽  
Vol 145 (2) ◽  
pp. 453-465 ◽  
Author(s):  
Zhikang Li ◽  
Shannon R M Pinson ◽  
William D Park ◽  
Andrew H Paterson ◽  
James W Stansel

The genetic basis for three grain yield components of rice, 1000 kernel weight (KW), grain number per panicle (GN), and grain weight per panicle (GWP), was investigated using restriction fragment length polymorphism markers and F4 progeny testing from a cross between rice subspecies japonica (cultivar Lemont from USA) and indica (cv. Teqing from China). Following identification of 19 QTL affecting these traits, we investigated the role of epistasis in genetic control of these phenotypes. Among 63 markers distributed throughout the genome that appeared to be involved in 79 highly significant (P < 0.001) interactions, most (46 or 73%) did not appear to have “main” effects on the relevant traits, but influenced the trait(s) predominantly through interactions. These results indicate that epistasis is an important genetic basis for complex traits such as yield components, especially traits of low heritability such as GN and GWP. The identification of epistatic loci is an important step toward resolution of discrepancies between quantitative trait loci mapping and classical genetic dogma, contributes to better understanding of the persistence of quantitative genetic variation in populations, and impels reconsideration of optimal mapping methodology and marker-assisted breeding strategies for improvement of complex traits.


1950 ◽  
Vol 28c (5) ◽  
pp. 493-512 ◽  
Author(s):  
W. E. Sackston

The pasmo pathogen sporulated freely on potato dextrose agar containing yeast extract. Spores suspended in water with gelatin as a spreader–sticker were sprayed onto flax plants at different stages of growth in field plots. Heaviest infections of pasmo resulted from inoculations at the flowering stage, lighter infections from inoculations on seedlings, and lightest infections from inoculations on ripening plants. Diluting the concentration of spores in the inoculum reduced disease intensity. The four flax varieties in the tests differed in reaction to pasmo. In decreasing order of susceptibility they were: Viking, Redwing, Royal, and Crystal. Heavy infections of pasmo caused premature ripening and reduced the seed yield and weight per thousand kernels of all four varieties. The effects of pasmo infection on seed yield and kernel weight were similar to those caused by a hot, dry climate, and by flax rust. Seed yield and kernel weight were reduced most markedly by inoculation at the flowering stage, less severely by inoculation at the seedling stage, and least of all by inoculation at the time of ripening. Seed yield and kernel weight from plots inoculated when the plants were ripening did not differ significantly from the uninoculated checks. Highly significant positive correlations between the data for seed yield and kernel weight indicated that much of the loss in yield resulted from a reduction in the size of individual seeds.


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