scholarly journals Weeds in fields with contrasting conventional and genetically modified herbicide–tolerant crops. I. Effects on abundance and diversity

2003 ◽  
Vol 358 (1439) ◽  
pp. 1819-1832 ◽  
Author(s):  
◽  
M. S. Heard ◽  
C. Hawes ◽  
G. T. Champion ◽  
S. J. Clark ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Conventional Treatment ◽  
Plant Density ◽  
Genetically Modified ◽  
Seed Rain ◽  
Transient Effects ◽  
Late Season ◽  
Herbicide Tolerant ◽  
Plant Densities ◽  
Total Seed

We compared the seedbanks, seed rains, plant densities and biomasses of weeds under two contrasting systems of management in beet, maize and spring oilseed rape. Weed seedbank and plant density were measured at the same locations in two subsequent seasons. About 60 fields were sown with each crop. Each field was split, one half being sown with a conventional variety managed according to the farmer's normal practice, the other half being sown with a genetically modified herbicide–tolerant (GMHT) variety, with weeds controlled by a broad–spectrum herbicide. In beet and rape, plant densities shortly after sowing were higher in the GMHT treatment. Following weed control in conventional beet, plant densities were approximately one–fifth of those in GMHT beet. In both beet and rape, this effect was reversed after the first application of broad–spectrum herbicide, so that late–season plant densities were lower in the GMHT treatments. Biomass and seed rain in GMHT crops were between one–third and one–sixth of those in conventional treatments. The effects of differing weed–seed returns in these two crops persisted in the seedbank: densities following the GMHT treatment were about 20% lower than those following the conventional treatment. The effect of growing maize was quite different. Weed density was higher throughout the season in the GMHT treatment. Late–season biomass was 82% higher and seed rain was 87% higher than in the conventional treatment. The difference was not subsequently detectable in the seedbank because the total seed return was low after both treatments. In all three crops, weed diversity was little affected by the treatment, except for transient effects immediately following herbicide application.

The effect of plant density on the reproductive structure of safflower in the Ord River valley

1966 ◽  
Vol 6 (22) ◽  
pp. 255 ◽  
Author(s):  
DF Beech ◽  
MJT Norman
Keyword(s):  
Plant Density ◽  
Dry Weight ◽  
Plant Size ◽  
Carthamus Tinctorius ◽  
Oil Yield ◽  
Research Station ◽  
Main Effect ◽  
Plant Densities ◽  
Mean Size ◽  
Total Seed

Safflower (Carthamus tinctorius L., variety Gila) was grown under irrigation at the Kimberley Research Station as a row crop at plant densities of 25,000 to 133,000 plants an acre and as a drilled crop at 593,000 plants an acre. The main effect of increasing plant density, within the range examined, was to reduce plant size (dry weight of tops and number of seed heads) ; the mean size of individual heads (number of seeds and their weight) showed little change. Though the relative seed and oil yield per head of primary, secondary, and tertiary heads remained fairly constant with increasing plant density, the increasing proportion of primary heads and the decreasing proportion of tertiary heads brought about corresponding changes in the contribution by primary and tertiary heads to total seed and oil yield. In contrast, the proportion of secondary heads and their contribution to seed and oil yield remained relatively stable.

Assessment of sowing dates and plant densities using CSM-CROPGRO-Soybean for soybean maturity groups in low latitude

2021 ◽  
pp. 1-14
Author(s):  
L. S. Sampaio ◽  
R. Battisti ◽  
M. A. Lana ◽  
K. J. Boote
Keyword(s):  
Management Practices ◽  
Field Experiments ◽  
Plant Density ◽  
Crop Model ◽  
Management Scenarios ◽  
Low Latitude ◽  
Area Index ◽  
Sowing Dates ◽  
Plant Densities ◽  
Maturity Groups

Abstract Crop models can be used to explain yield variations associated with management practices, environment and genotype. This study aimed to assess the effect of plant densities using CSM-CROPGRO-Soybean for low latitudes. The crop model was calibrated and evaluated using data from field experiments, including plant densities (10, 20, 30 and 40 plants per m2), maturity groups (MG 7.7 and 8.8) and sowing dates (calibration: 06 Jan., 19 Jan., 16 Feb. 2018; and evaluation: 19 Jan. 2019). The model simulated phenology with a bias lower than 2 days for calibration and 7 days for evaluation. Relative root mean square error for the maximum leaf area index varied from 12.2 to 31.3%; while that for grain yield varied between 3 and 32%. The calibrated model was used to simulate different management scenarios across six sites located in the low latitude, considering 33 growing seasons. Simulations showed a higher yield for 40 pl per m2, as expected, but with greater yield gain increments occurring at low plant density going from 10 to 20 pl per m2. In Santarém, Brazil, MG 8.8 sown on 21 Feb. had a median yield of 2658, 3197, 3442 and 3583 kg/ha, respectively, for 10, 20, 30 and 40 pl per m2, resulting in a relative increase of 20, 8 and 4% for each additional 10 pl per m2. Overall, the crop model had adequate performance, indicating a minimum recommended plant density of 20 pl per m2, while sowing dates and maturity groups showed different yield level and pattern across sites in function of the local climate.

Canola seed yield and phenological responses to plant density

2016 ◽  
Vol 96 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Gan Yantai ◽  
K. Neil Harker ◽  
H. Randy Kutcher ◽  
Robert H. Gulden ◽  
Byron Irvine ◽  
...  
Keyword(s):  
Seed Yield ◽  
Plant Density ◽  
Block Design ◽  
Positive Association ◽  
High Yield ◽  
Western Canada ◽  
Flowering Period ◽  
Canola Seed ◽  
Randomized Complete Block Design ◽  
Plant Densities

Optimal plant density is required to improve plant phenological traits and maximize seed yield in field crops. In this study, we determined the effect of plant density on duration of flowering, post-flowering phase, and seed yield of canola in diverse environments. The field study was conducted at 16 site-years across the major canola growing area of western Canada from 2010 to 2012. The cultivar InVigor® 5440, a glufosinate-resistant hybrid, was grown at five plant densities (20, 40, 60, 80, and 100 plants m−2) in a randomized complete block design with four replicates. Canola seed yield had a linear relationship with plant density at 8 of the 16 site-years, a quadratic relationship at 4 site-years, and there was no correlation between the two variables in the remaining 4 site-years. At site-years with low to medium productivity, canola seed yield increased by 10.2 to 14.7 kg ha−1 for every additional plant per square metre. Averaged across the 16 diverse environments, canola plants spent an average of 22% of their life cycle flowering and another 27% of the time filling seed post-flowering. Canola seed yield had a negative association with duration of flowering and a positive association with the days post-flowering but was not associated with number of days to maturity. The post-flowering period was 12.7, 14.7, and 12.6 d (or 55, 68, and 58%) longer in high-yield experiments than in low-yield experiments in 2010, 2011, and 2012, respectively. We conclude that optimization of plant density for canola seed yield varies with environment and that a longer post-flowering period is critical for increasing canola yield in western Canada.

Plant height and height of the main ear in maize (Zea mays L.) at different locations and different plant densities

2002 ◽  
Vol 50 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Z. Gyenes-Hegyi ◽  
I. Pók ◽  
L. Kizmus ◽  
Keyword(s):  
Plant Height ◽  
Plant Density ◽  
Close Correlation ◽  
Plant Size ◽  
Considerable Effect ◽  
Maximum Height ◽  
The Best Approximation ◽  
Significant Difference ◽  
Plant Densities ◽  
Ear Height

The plant height and the height of the main ear were studied over two years in twelve single cross maize hybrids sown at three different plant densities (45, 65 and 85 thousand plants/ha) at five locations in Hungary (Keszthely, Gönc, Gyöngyös, Sopronhorpács, Martonvásár). The results revealed that plant height and the height of the main ear are important variety traits and are in close correlation with each other. It was found that the hybrids grew the tallest when the genetic distance between the parental components was greatest (Mv 4, Mv 5). The height of the main ear was also the greatest in these hybrids, and the degree of heterosis was highest (193% for plant height, 194% for the height of the main ear). The shortest hybrids were those developed between related lines (Mv 7, Mv 11). In this case the heterosis effect was the lowest for both plant height (128%) and the height of the main ear (144%). The ratio of the height of the main ear to the plant height was stable, showing little variation between the hybrids (37–44%). As maize is of tropical origin it grows best in a humid, warm, sunny climate. Among the locations tested, the Keszthely site gave the best approximation to these conditions, and it was here that the maize grew tallest. The dry, warm weather in Gyöngyös stunted the development of the plants, which were the shortest at this location. Plant density had an influence on the plant size. The plants were shortest when sown at a plant density of 45,000 plants/ha, and the main ears were situated the lowest in this case. At all the locations the plant and main ear height rose when the plant density was increased to 65,000 plants/ha. At two sites (Gönc and Sopronhorpács) the plants attained their maximum height at the greatest plant density (85,000 plants/ha). In Keszthely there was no significant difference between these two characters at plant densities of 65 and 85 thousand plants/ha, while in Gyöngyös and Martonvásár the greatest plant density led to a decrease in the plant and main ear height. The year had a considerable effect on the characters tested.

scholarly journals Fall and spring seeding date effects on herbicide-tolerant canola (Brassica napus L.) cultivars

2004 ◽  
Vol 84 (2) ◽  
pp. 419-430 ◽  
Author(s):  
G. W. Clayton ◽  
K. N. Harker ◽  
J. T. O’Donovan ◽  
R. E. Blackshaw ◽  
L. M. Dosdall ◽  
...  
Keyword(s):  
Field Experiments ◽  
Plant Density ◽  
Early Spring ◽  
Yield Response ◽  
Management Options ◽  
Brassica Napus L ◽  
Seeding Date ◽  
Herbicide Tolerant ◽  
Root Maggot ◽  
Crops Yield

More flexible and effective weed control with herbicide-tolerant B. napus canola allows for additional seeding management options, such as fall (dormant) and early spring (ES) seeding. Field experiments were conducted at Lacombe and Beaverlodge (1999–2001), Didsbury (1999–2000), and Lethbridge (2000–2001), Alberta, Canada, primarily to evaluate the effect of fall (late October-November), ES (late April-early May), and normal spring (NS) (ca. mid-May) seeding dates on glufosinate-, glyphosate-, and imidazolinone-tolerant canola development and yield. Fall seeding resulted in 46% lower plant density and nearly double the dockage than spring seeding. ES-seeded canola had 19% higher seed yield and 2.1% higher oil content than fall-seeded canola. ES seeding significantly increased yield compared to fall-seeded canola for 8 of 10 site -years or compared to NS seeding for 4 of 10 site-years; ES-seeded canola equalled the yield of NS-seeded canola for 6 of 10 site-years. Yield response to seeding date did not differ among herbicide-tolerant cultivars. Seeding date did not influence root maggot damage. Seeding canola as soon as possible in spring increases the likelihood of optimizing canola yield and quality compared to fall seeding and traditional spring seeding dates. Key words: Dormant seeding, seeding management, root maggot, herbicide-resistant crops, yield components, operational diversity

scholarly journals PLANT DENSITY AND NITROGEN FERTILIZATION ON COMMON BEAN NUTRITION AND YIELD

2017 ◽  
Vol 30 (3) ◽  
pp. 670-678 ◽  
Author(s):  
ROGÉRIO PERES SORATTO ◽  
TIAGO ARANDA CATUCHI ◽  
EMERSON DE FREITAS CORDOVA DE SOUZA ◽  
JADER LUIS NANTES GARCIA
Keyword(s):  
Grain Yield ◽  
Common Bean ◽  
Nitrogen Fertilization ◽  
Dry Matter ◽  
Plant Density ◽  
N Fertilization ◽  
N Concentration ◽  
Plant Densities ◽  
N Rates ◽  
Lower Plant

ABSTRACT The objective of this work was to evaluate the effect of plant densities and sidedressed nitrogen (N) rates on nutrition and productive performance of the common bean cultivars IPR 139 and Pérola. For each cultivar, a randomized complete block experimental design was used in a split-plot arrangement, with three replicates. Plots consisted of three plant densities (5, 7, and 9 plants ha-1) and subplots of five N rates (0, 30, 60, 120, and 180 kg ha-1). Aboveground dry matter, leaf macro- and micronutrient concentrations, yield components, grain yield, and protein concentration in grains were evaluated. Lower plant densities (5 and 7 plants m-1) increased aboveground dry matter production and the number of pods per plant and did not reduce grain yield. In the absence of N fertilization, reduction of plant density decreased N concentration in common bean leaves. Nitrogen fertilization linearly increased dry matter and leaf N concentration, mainly at lower plant densities. Regardless of plant density, the N supply linearly increased grain yield of cultivars IPR 139 and Pérola by 17.3 and 52.2%, respectively.

Response of pigeon pea (Cajanus cajan (L.) Millsp.) to plant density and phosphorus fertilizer under dryland conditions

1981 ◽  
Vol 97 (1) ◽  
pp. 119-124 ◽  
Author(s):  
I. P. S. Ahlawat ◽  
C. S. Saraf
Keyword(s):  
Grain Yield ◽  
Shoot Growth ◽  
Plant Density ◽  
Sandy Loam ◽  
Phosphate Fertilizer ◽  
Pigeon Pea ◽  
Phosphorus Fertilizer ◽  
Total N ◽  
Root And Shoot Growth ◽  
Plant Densities

SUMMARYField studies were made for 2 years on a sandy loam soil under dryland conditions of north-west India with three pigeon-pea varieties in relation to plant density and the application of phosphate fertilizer. Varieties Pusa Ageti and P4785 with better developed root system and profuse nodulation had higher grain and stalk yield, and higher N and P yield than Prabhat. Root and shoot growth and root nodulation were adversely affected with increasing plant densities in the range 50 × 103 and 150 × 103 plants/ha. Stalk and total N and P yield increased with increasing plant density. Plant density of 117 × 103 plants/ha produced maximum grain yield of 1·53 t/ha. Phosphorus fertilizer promoted root and shoot growth, intensity and volume of nodulation and increased grain, stalk, N and P yield. The effect of plant density on grain yield was more pronounced in the presence of phosphate fertilizer. The economic optimum rate of P ranged between 22·1 and 23·1 kg/ha under different plant densities.

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