Evapotranspiration Crop Coefficients Predicted Using Growing-Degree-Days

A field experiment was carried out during the kharif of 2014 and 2015 to evaluate the yield potential, economics and thermal utilization in eleven finger millet varieties under the rainfed condition of the sub-humid environment of South Bihar of Eastern India. Results revealed that the significantly higher grain yield (20.41 q ha-1), net returns (Rs 25301) and B: C ratio (1.51) was with the finger millet variety ‘GPU 67’ but was being at par to ‘GPU28’and ‘RAU-8’, and significantly superior over remaining varieties. The highest heat units (1535.1oC day), helio-thermal units (7519.7oC day hours), phenothermal index (19.4 oC days day-1) were recorded with variety ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ and lowest in ‘VL 149’ at 50 % anthesis stage. Similarly, the highest growing degree days (2100 oC day), helio-thermal units (11035.8 oC day hours) were noted with ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ at maturity. The highest heat use efficiency (0.97 kg ha-1 oC day) and helio-thermal use efficiency (0.19 kg ha-1 oC day hour) were in ‘GPU 67’ followed by ‘VL 315’.

Download Full-text

Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed

Weed Technology ◽

10.1017/wet.2019.68 ◽

2019 ◽

Vol 33 (6) ◽

pp. 800-807 ◽

Cited By ~ 3

Author(s):

Graham W. Charles ◽

Brian M. Sindel ◽

Annette L. Cowie ◽

Oliver G. G. Knox

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Field Studies ◽

Growing Degree Days ◽

Degree Days ◽

Weed Density ◽

High Level ◽

The Cost ◽

Planting Season

AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

Download Full-text

Future projections of growing degree days and frost in New Zealand and some implications for grape growing

Weather and Climate ◽

10.2307/26169696 ◽

2008 ◽

Vol 28 ◽

pp. 17 ◽

Cited By ~ 21

Author(s):

Tait

Keyword(s):

New Zealand ◽

Growing Degree Days ◽

Degree Days ◽

Future Projections

Download Full-text

Growth and Development of Purple Nutsedge Based on Days or Thermal Units

Planta Daninha ◽

10.1590/0100-83582015000200001 ◽

2015 ◽

Vol 33 (2) ◽

pp. 165-173 ◽

Cited By ~ 1

Author(s):

R.S.O. Lima ◽

E.C.R. Machado ◽

A.P.P. Silva ◽

B.S. Marques ◽

M.F. Gonçalves ◽

...

Keyword(s):

Plant Growth ◽

Mathematical Models ◽

Growth And Development ◽

Dry Matter ◽

Cyperus Rotundus ◽

Growing Degree Days ◽

Plant Growth And Development ◽

Degree Days ◽

Purple Nutsedge ◽

Independent Trials

This work was carried out with the objective of elaborating mathematical models to predict growth and development of purple nutsedge (Cyperus rotundus) based on days or accumulated thermal units (growing degree days). Thus, two independent trials were developed, the first with a decreasing photoperiod (March to July) and the second with an increasing photoperiod (August to November). In each trial, ten assessments of plant growth and development were performed, quantifying total dry matter and the species phenology. After that, phenology was fit to first degree equations, considering individual trials or their grouping. In the same way, the total dry matter was fit to logistic-type models. In all regressions four temporal scales possibilities were assessed for the x axis: accumulated days or growing degree days (GDD) with base temperatures (Tb) of 10, 12 and 15 oC. For both photoperiod conditions, growth and development of purple nutsedge were adequately fit to prediction mathematical models based on accumulated thermal units, highlighting Tb = 12 oC. Considering GDD calculated with Tb = 12 oC, purple nutsedge phenology may be predicted by y = 0.113x, while species growth may be predicted by y = 37.678/(1+(x/509.353)-7.047).

Download Full-text

CHLOROGENIC ACID CONTENT OF SUNFLOWER SEED FLOUR AS AFFECTED BY SEEDING AND HARVEST DATE

Canadian Journal of Plant Science ◽

10.4141/cjps76-146 ◽

1976 ◽

Vol 56 (4) ◽

pp. 901-905 ◽

Cited By ~ 4

Author(s):

D. G. DORRELL

Keyword(s):

Chlorogenic Acid ◽

Acid Content ◽

Vegetative Growth ◽

Sunflower Seed ◽

Growing Season ◽

Growing Degree Days ◽

Degree Days ◽

Normal Field ◽

Seed Flour ◽

Seeding Date

The effect of seeding date on the chlorogenic acid content of sunflower seed flour was determined by seeding the cultivars Krasnodarets and Peredovik at seven dates, starting on 14 May, over 3 yr. Sequential plantings were made at increments of approximately 70 growing degree days (base = 5.6 C). Plants were harvested at normal field maturity. The time and rate of deposition of chlorogenic acid was determined by harvesting plants at 7-day intervals from 21 to 49 days after flowering. The seeds were dehulled and defatted before determining the chlorogenic acid content of the flour. Chlorogenic acid content declined steadily from an average of 4.22% for the first seeding to 3.30% for the last seeding. About one-half of the total chlorogenic acid was present 21 days after flowering. Deposition continued rapidly for the next 14 days then the level began to stabilize. Delay in seeding tended to shorten the period of vegetative growth and shift the deposition of chlorogenic acid to a cooler portion of the growing season. It is suggested that a combination of these factors caused the reduction in chlorogenic acid content of sunflower flour.

Download Full-text