scholarly journals Initial growth and development of southern sandbur based on thermal units

2014 ◽  
Vol 32 (2) ◽  
pp. 335-343 ◽  
Author(s):  
E.C.R. Machado ◽  
R.S.O. Lima ◽  
A.P.P. Silva ◽  
B.S. Marques ◽  
M.F. Gonçalves ◽  
...  
Keyword(s):  
Growth And Development ◽  
Dry Matter ◽  
Integrated Management ◽  
Base Temperature ◽  
Initial Growth ◽  
Agricultural Systems ◽  
Degree Days ◽  
Flowering Stage ◽  
Weed Biology ◽  
Best Fit

Availability of basic information on weed biology is an essential tool for designing integrated management programs for agricultural systems. Thus, this study was carried out in order to calculate the base temperature (Tb) of southern sandbur (Cenchrus echinatus), as well as fit the initial growth and development of the species to accumulated thermal units (growing degree days - GDD). For that purpose, experimental populations were sown six times in summer/autumn conditions (decreasing photoperiod) and six times in winter/spring condition (increasing photoperiod). Southern sandbur phenological evaluations were carried out, on alternate days, and total dry matter was measured when plants reached the flowering stage. All the growth and development fits were performed based on thermal units by assessing five base temperatures, as well as the absence of it. Southern sandbur development was best fit with Tb = 12 ºC, with equation y = 0,0993x, where y is the scale of phenological stage and x is the GDD. On average, flowering was reached at 518 GDD. Southern sandbur phenology may be predicted by using mathematical models based on accumulated thermal units, adopting Tb = 12 ºC. However, other environmental variables may also interfere with species development, particularly photoperiod.

scholarly journals Growth and development of sourgrass based on days or thermal units

2014 ◽  
Vol 32 (3) ◽  
pp. 483-490 ◽  
Author(s):  
B.S. Marques ◽  
A.P.P. Silva ◽  
R.S.O. Lima ◽  
E.C.R. Machado ◽  
M.F. Gonçalves ◽  
...  
Keyword(s):  
Time Scale ◽  
Environmental Variables ◽  
Growth And Development ◽  
Dry Matter ◽  
Growing Degree Days ◽  
Dry Matter Accumulation ◽  
Initial Growth ◽  
Degree Days ◽  
Independent Trials ◽  
Mass Accumulation

This work was carried out with the objective of evaluating growth and development of sourgrass (Digitaris insularis) based on days or thermal units (growing degree days - GDD). Two independent trials were developed aiming to quantify the species' phenological development and total dry matter accumulation in increasing or decreasing photoperiod conditions. Plants were grown in 4 L plastic pots, filled with commercial substrate, adequately fertilized. In each trial, nine growth evaluations were carried out, with three replicates. Phenological development of sourgrass was correctly fit to time scale in days or GDD, through linear equation of first degree. Sourgrass has slow initial growth, followed by exponential dry matter accumulation, in increasing photoperiod condition. Maximum total dry matter was 75 and 6 g per plant for increasing and decreasing photoperiod conditions, respectively. Thus, phenological development of sourgrass may be predicted by mathematical models based on days or GDD; however, it should be noted that other environmental variables interfere on the species' growth (mass accumulation), especially photoperiod.

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

2015 ◽  
Vol 33 (2) ◽  
pp. 165-173 ◽  
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).

Studies on Determination of Critical Growing Degree Days, Base Temperature (Tb) and Response of Temperature Variations on Flowering and Yield per se in Cowpea [Vigna unguiculata (L.) Walp.]

2020 ◽  
Author(s):  
Venkatesh Bondade ◽  
Sanjeev K Deshpande
Keyword(s):  
Dry Matter ◽  
Significant Negative Correlation ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Temperature Variations ◽  
Days To Flowering ◽  
Matter Production ◽  
Flowering Initiation

Growing degree days (GDD) or heat units accumulation is the major factor that affects the dry matter production in the plants. In the present investigation eleven genotypes were used to screen for temperature insensitivity through staggered plantings across the seasons in a year. Days to flowering initiation was recorded and base temperature (Tb) was determined using mean daily air temperature (MAT). GDD of individual genotypes was estimated using base temperatures of particular genotypes. It was observed that the GDD, days to flowering initiation and yield were exhibited high variation across the seasons, the flowering time from days to planting (FTDAP) registered significant negative correlation with GDD and MAT and positively correlated with yield. Whereas GDD is positively correlated with MAT and negatively correlated with yield. Here three genotypes namely, IC202926, IC198326 and IC257428 were identified as temperature insensitive genotypes as their performances were comparable across the seasons without much fluctuations.

scholarly journals Influence of Various Polyethylene Mulch Colors on Growth and Development of `Vates' Collards

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 600D-600
Author(s):  
J.M Kemble ◽  
J. Brown ◽  
E. Simonne
Keyword(s):  
Growth And Development ◽  
Soil Depth ◽  
Dry Weight ◽  
Base Temperature ◽  
Fresh Weight ◽  
Degree Days ◽  
Marketable Yield ◽  
Soil Temperatures ◽  
Polyethylene Mulch ◽  
Final Harvest

The effect of various mulch colors (black, yellow, red, blue, white, and aluminum) on growth and development of `Vates' collards was evaluated in Fall 1996 at the E.V. Smith Research Center in Shorter, Ala. Black polyethylene mulch was installed onto raised, fumigated beds, then sprayed with a 1: 2 (v/v) mixture of exterior oil-based enamel paint to paint thinner with one of the five mulch colors listed. Five-week-old plants were transplanted into beds. Beginning two weeks after transplanting and continuing every other week thereafter, heads were harvested to determine head fresh weight and dry weight. Hourly soil temperatures at 10 cm soil depth were recorded and growing degree days (GDDs) with a base temperature of 4.4 °C were calculated. At two weeks after transplanting, average head fresh and dry weight were highest for the aluminum-colored treatment with head fresh (24.7 and 12.3 g, respectively) and dry weights (2.7 and 1.3 g, respectively) twice that of the yellow treatment (P ≤ 0.05). By four weeks after transplanting and up through the final harvest, marketable yield and average head fresh weights did not differ among the treatments (17,900 kg/ha, 1.4 kg per head, respectively). The red and black mulch treatments accumulated more GDDs than the other treatments, but total marketable yields did not differ among any treatments.

scholarly journals Growth and development of honey weed based on days or thermal units

2014 ◽  
Vol 32 (1) ◽  
pp. 81-89 ◽  
Author(s):  
A.P.P. Silva ◽  
B.S. Marques ◽  
R.S.O. Lima ◽  
E.C.R. Machado ◽  
M.F. Gonçalves ◽  
...  
Keyword(s):  
Growth And Development ◽  
Environmental Influence ◽  
Dry Mass ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Different Seasons ◽  
Leonurus Sibiricus ◽  
Mass Accumulation ◽  
Plant Dry Mass

This work was carried out with the objective of evaluating the growth and development of honey weed (Leonurus sibiricus) based on days or thermal units (growing degree days). Thus, two independent trials were developed to quantify the phenological development and total dry mass accumulation in increasing or decreasing photoperiod conditions. Considering only one growing season, honey weed phenological development was perfectly fit to day scale or growing degree days, but with no equivalence between seasons, with the plants developing faster at increasing photoperiods, and flowering 100 days after seeding. Even day-time scale or thermal units were not able to estimate general honey weed phenology during the different seasons of the year. In any growing condition, honey weed plants were able to accumulate a total dry mass of over 50 g per plant. Dry mass accumulation was adequately fit to the growing degree days, with highlights to a base temperature of 10 ºC. Therefore, a higher environmental influence on species phenology and a lower environmental influence on growth (dry mass) were observed, showing thereby that other variables, such as the photoperiod, may potentially complement the mathematical models.

Fish growth and degree-days I: selecting a base temperature for a within-population study

2014 ◽  
Vol 71 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Kyle A. Chezik ◽  
Nigel P. Lester ◽  
Paul A. Venturelli
Keyword(s):  
Growth And Development ◽  
Population Studies ◽  
Growing Season ◽  
Fish Growth ◽  
Future Research ◽  
Base Temperature ◽  
Degree Days ◽  
Single Population ◽  
Growth Variation ◽  
Length Data

Degree-days (DD) are an increasingly popular method for explaining variation in fish growth and development. By including a base temperature (To) the DD formula limits calculations to temperatures that are relevant to growth. However, our review of growth studies shows multiple To values in use for a given fish species. To determine how To affects the ability of DD to explain within-population growth variation, we first show that the ability of DD to describe a growing season is robust to low values of To. We then analyze immature length data from eight species and 85 water bodies in North America to show that there is a broad range of To values that effectively explain growth variation. Based on these results, we argue that precise To estimates are unwarranted for most single-population studies and recommend standard To values (0, 5, 10, 15 °C). Standardization facilitates comparative studies and promotes the use of DD in future research. To this end, we provide equations for converting annual DD at a given To to annual DD at a standard To.

scholarly journals Growth and Development of Oenothera fruticosa Is Influenced by Vernalization Duration, Photoperiod, Forcing Temperature, and Plant Growth Regulators

2001 ◽  
Vol 126 (3) ◽  
pp. 269-274 ◽  
Author(s):  
Emily A. Clough ◽  
Arthur C. Cameron ◽  
Royal D. Heins ◽  
William H. Carlson
Keyword(s):  
Plant Growth ◽  
Plant Height ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Growth And Development ◽  
Base Temperature ◽  
Trimethylammonium Chloride ◽  
Degree Days ◽  
Flower Number ◽  
Butanedioic Acid

Influences of vernalization duration, photoperiod, forcing temperature, and plant growth regulators (PGRs) on growth and development of Oenothera fruticosa L. `Youngii-lapsley' (`Youngii-lapsley' sundrops) were determined. Young plants were vernalized at 5 °C for 0, 3, 6, 9, 12, or 15 weeks under a 9-hour photoperiod and subsequently forced in a 20 °C greenhouse under a 16-hour photoperiod. Only one plant in 2 years flowered without vernalization, while all plants flowered after receiving a vernalization treatment, regardless of its duration. Thus, O. fruticosa had a nearly obligate vernalization requirement. Time to visible bud and flower decreased by ≈1 week as vernalization duration increased from 3 to 15 weeks. All plants flowered under 10-, 12-, 13-, 14-, 16-, or 24-hour photoperiods or a 4-hour night interruption (NI) in a 20 °C greenhouse following 15-weeks vernalization at 5 °C. Time to flower decreased by ≈2 weeks, flower number decreased, and plant height increased as photoperiod increased from 10 to 16 hours. Days to flower, number of new nodes, and flower number under 24 hour and NI were similar to that of plants grown under a 16-hour photoperiod. In a separate study, plants were vernalized for 15 weeks and then forced under a 16-h photoperiod at 15.2, 18.2, 20.6, 23.8, 26.8, or 29.8 °C (average daily temperatures). Plants flowered 35 days faster at 29.8 °C but were 18 cm shorter than those grown at 15.2 °C. In addition, plants grown at 29.8 °C produced only one-sixth the number of flowers (with diameters that were 3.0 cm smaller) than plants grown at 15.2 °C. Days to visible bud and flowering were converted to rates, and base temperature (Tb) and thermal time to flowering (degree-days) were calculated as 4.4 °C and 606 °days, respectively. Effects of foliar applications of ancymidol (100 mg·L-1), chlormequat (1500 mg·L-1), paclobutrazol (30 mg·L-1), daminozide (5000 mg·L-1), and uniconazole (15 mg·L-1) were determined on plants vernalized for 19 weeks and then forced at 20 °C under a 16-h photoperiod. Three spray applications of uniconazole reduced plant height at first flower by 31% compared with that of nontreated controls. All other PGRs did not affect plant growth. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); (2-chloroethyl) trimethylammonium chloride (chlormequat); butanedioic acid mono-(2,2-dimethyl hydrazide) (daminozide); (2R,3R+2S,3S)-1-(4-chlorophenyl-4,4-dimethyl-2-[1,2,4-triazol-1-yl]) (paclobutrazol); (E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3-ol (uniconazole).

RESPONSE OF PEAS TO ENVIRONMENT: IV. EFFECT OF FIVE SOIL WATER REGIMES ON GROWTH AND DEVELOPMENT OF PEAS

1968 ◽  
Vol 48 (2) ◽  
pp. 129-137 ◽  
Author(s):  
A. R. Maurer ◽  
H. F. Fletcher ◽  
D. P. Ormrod
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Growth And Development ◽  
Dry Matter ◽  
Fresh Weight ◽  
Water Regimes ◽  
Severe Water Stress ◽  
Water Conditions ◽  
Before And After ◽  
Soil Water Conditions

Pea plants growing in "weighing lysimeters" were subjected to five soil-water regimes to determine their response to varying conditions of soil water imposed at different stages of development. Plants subjected to a minimal water stress developed luxuriantly and continued to grow up to the harvest period. Pea yield and plant height were not reduced, but fresh weight and dry matter were less if irrigation was applied when soil water fell to 60% rather than 88% of that available. A severe water stress after blossom reduced pea yield, irrespective of soil-water conditions prior to blossom. Plants which had been given ample soil water before blossom wilted visibly when a severe stress was imposed in the post-blossom period, yet wilting did not occur in plants subjected to severe water stress both before and after blossom. Severe water stress prior to blossom did not cause a decrease in pea yield if ample soil moisture was made available after blossom.

Earliness of an indeterminate crop, Vigna unguiculata (L.) Walp., as affected by drought, temperature, and plant density

1982 ◽  
Vol 33 (3) ◽  
pp. 531 ◽  
Author(s):  
DA Grantz ◽  
AE Hall
Keyword(s):  
Vigna Unguiculata ◽  
Dry Matter ◽  
Plant Density ◽  
Severe Drought ◽  
Base Temperature ◽  
Semiarid Environments ◽  
Land Race ◽  
Sowing Dates ◽  
Moderate Drought ◽  
Extreme Variability

Earliness of an indeterminate crop, Vigna unguiculata (L.) Walp., was studied to aid development of selection techniques for improving adaptation to semiarid environments. Earliness was based upon the time of first appearance of floral buds and flowers, proportion of shoot dry matter in reproductive parts at midseason, and time of maturity. A cowpea land race, Chino 3, was earlier than cultivars California Blackeye No. 3 and No. 5, with respect to all of these criteria. Time to flowering from different sowing dates was related to heat units, which were calculated from daily mean air temperature above a base temperature of c. 10�C. The proportions of shoot dry matter in reproductive parts during early stages of pod-filling were greater with moderate drought but were unaffected by severe drought, compared with the response of adequately irrigated plants. Widely spaced plants exhibited greater proportions of shoot dry matter in reproductive parts at midseason than did closely spaced plants. Adaptation of cowpeas to semiarid environments may be improved by selecting for early partitioning of carbohydrates to reproductive parts. Selection for early partitioning may be more effective in adequately watered conditions, owing to extreme variability under drought, and at wide and precise spacing.

scholarly journals Grasses and legumes as cover crop in no-tillage system in northeastern Pará Brazil

2014 ◽  
Vol 44 (4) ◽  
pp. 411-418 ◽  
Author(s):  
Renato Alves Teixeira ◽  
Tatiana Gazel Soares ◽  
Antonio Rodrigues Fernandes ◽  
Anderson Martins de Souza Braz
Keyword(s):  
Half Life ◽  
Dry Matter ◽  
C:N Ratio ◽  
Life Time ◽  
Dry Matter Production ◽  
Agricultural Systems ◽  
Climate Conditions ◽  
Jack Bean ◽  
No Till ◽  
Matter Production

Studies to select one or more species of coverage plants adapted to Amazonian soil and climate conditions of the Amazon are a promising strategy for the improvement of environmental quality, establishing no-till agricultural systems, and thereby reducing the impacts of monoculture farming. The aim of this study was to assess the persistence time, half-life time, macronutrient content and accumulation, and C:N ratio of straw coverage in a Ultisol in northeastern Pará. Experimental design was randomized blocks with five treatments and five replicates. Plants were harvested after 105 days, growth and biomass production was quantified. After 84 days, soil coverage was 97, 85, 52, 50, and 15% for signalgrass (Brachiaria brizantha) (syn. Urochloa), dense crowngrass (Panicum purpurascens), jack bean (Canavalia ensiformes), pearl millet (Pennisetum americanum) and sunn hemp (Crotalaria juncea,), respectively. Signalgrass yielded the greatest dry matter production (9,696 kg ha-1). It also had high C:N ratio (38.4), long half-life (86.5 days) and a high persistence in the field. Jack bean also showed high dry matter production (8,950 kg ha-1), but it had low C:N ratio (17.4) and lower half-life time (39 days) than the grasses. These attributes indicate that signalgrass and jack bean have a high potential for use as cover plants in no-till agricultural systems in the State of Pará.

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