Effects of interspecific competition on periodic shoot elongation in oak seedlings

1996 ◽  
Vol 26 (11) ◽  
pp. 1934-1942 ◽  
Author(s):  
Catherine Collet ◽  
Henri Frochot
Keyword(s):  
Interspecific Competition ◽  
Growing Season ◽  
Shoot Elongation ◽  
Field Conditions ◽  
Growing Seasons ◽  
Controlled Conditions ◽  
Oak Seedlings

The effects of interspecific competition on periodic shoot elongation of Quercuspetraea (Matt.) Liebl. and Quercusrobur L. seedlings were investigated in two experiments. In the first experiment, conducted under field conditions, young oaks were grown under various levels of grass and shrub competition. The number of growth flushes produced by the seedlings was assessed on three dates during the summer. In the second experiment, conducted under controlled conditions, seedlings were grown under various levels of competition and watering regimes. Biweekly measurements of shoot elongation were made during two consecutive growing seasons. Seedlings grown with competition produced fewer growth flushes during the growing season, and those flushes were delayed. They also produced fewer growth units during each flush and those growth units were shorter. All the seedlings grown without competition flushed at the same time during the entire growing season. On the contrary, the seedlings grown with competition showed synchronous flushing in spring, but became asynchronous later in the growing season.

Shoot morphology and shoot growth potential in 1-year-old Scots pine seedlings

1981 ◽  
Vol 11 (4) ◽  
pp. 789-795 ◽  
Author(s):  
S. Thompson
Keyword(s):  
Scots Pine ◽  
Shoot Growth ◽  
Growing Season ◽  
Shoot Elongation ◽  
Growth Potential ◽  
Shoot Morphology ◽  
Growing Seasons ◽  
Pine Seedlings

When seedlings of a single seed source of Scots pine (Pinussylvestris L.) were raised for 26 weeks in a naturally lit, heated greenhouse, two types of shoot morphology were observed. Type 1 was that normally found in 1-year-old seedlings. Type 2 had a shoot morphology similar to that of seedlings raised outdoors for two growing seasons. When compared with type 1 plants, type 2 plants had an earlier start to shoot elongation, set their buds earlier, and stopped shoot elongation sooner. After one growing season, type 2 plants were shorter, had fewer stem units for shoot elongation in the second season, but carried a greater foliage biomass than 1-year-old type plants. After two seasons they remained shorter. Thus, plant rearing practices which result in the production of seedlings with this type of shoot morphology arc undesirable.The relationship between early "budsct," shoot morphology, and plant height suggests that the proportion of seedlings with a 2-year-old shoot morphology after one growing season in a heated greenhouse may be used as an early test for height growth potential in seed origins and possibly in progenies of north temperate pine species.

Shoot elongation of black oak and white oak sprouts

1979 ◽  
Vol 9 (4) ◽  
pp. 489-494 ◽  
Author(s):  
Paul S. Johnson
Keyword(s):  
Growing Season ◽  
Shoot Elongation ◽  
White Oak ◽  
Growing Seasons ◽  
Black Oak ◽  
Stump Diameter

Weekly events in shoot elongation were observed and measured for 43 black oak (Quercusvelutina Lam.) and 41 white oak (Q. alba L.) sprouts in their second growing season. In addition, total net shoot elongation (i.e., elongation minus current dieback) was measured at the ends of the first four growing seasons. Sprouts originated from stumps with diameters of 0.6 in. (1.5 cm) to 12 in. (30.5 cm). Average net elongation of both species reached a weekly maximum of 0.6 ft (18.3 cm) during the 3rd growth week (May 4–10). Although elongation among individual sprouts was extremely variable, most sprouts of both species flushed two or more times during the 17-week study period. Periods of individual flushes ranged from 1 to 3 weeks and most occurred during the first 13 growth weeks. Based on regression estimates, 2nd-year gross shoot elongation increased with increasing stump diameter up to 6 in. (15.2 cm); above this diameter shoot elongation decreased. Net 4-year elongation of both species also tended to increase with increasing stump diameter up to 6 in. There were no significant differences between species in 2nd-year gross elongation or in total 4-year net elongation.

scholarly journals Prohexadione-Ca Affects Vegetative Growth of the Rejuvenated Shoots in Walnut Trees

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 558-561 ◽  
Author(s):  
Anita Solar ◽  
Jerneja Jakopič ◽  
Robert Veberič ◽  
Franci Štampar
Keyword(s):  
Vegetative Growth ◽  
Growth Inhibitor ◽  
Growing Season ◽  
Shoot Elongation ◽  
Strong Reduction ◽  
Growing Seasons ◽  
Second Growth ◽  
Final Length ◽  
Prohexadione Calcium ◽  
Summer Growth

Prohexadione-calcium (ProCa), formulated as Regalis, was tested as a vegetative growth inhibitor in rejuvenated annual shoots of 14-year-old mother trees in the ‘Franquette’ walnut cultivar. ProCa was applied three times during growing seasons in 2005 (Y5) and 2006 (Y6). This was during the second half of spring growth flush, the resting phase between the first and second growth flushes, and in the middle of summer growth flush. As a result, treated shoots in the upper part of the canopy were shorter than untreated ones during the whole growing season in both years. In Y5, two treatments of ProCa (250 mg·L−1), applied until the middle of June, inhibited shoot elongation during summer growth, which was the main purpose of the experiment. The reduction of shoot elongation was between 18% [lower shoots in the canopy (LS)] and 33% [upper shoots (US)]. After three ProCa applications, also the final length of the shoots was reduced by 5% (US) and 18% (LS). In Y6, when 100 mg·L−1 of ProCa had been used, strong reduction (24%) was observed only in US after two treatments. Summer growth was not reduced, probably as a result of an interaction between lower concentration of ProCa and stress caused by a water deficit and extremely high temperatures during the summer. On the base of the shoots, three treatments of ProCa (100 mg·L−1) in Y6 increased the ratio between wood and pith and, consequently, increased the quality and uniformity of the scion wood. Further research into additional cultivars and ProCa concentrations is recommended to optimize the terms of application.

scholarly journals Screening of Okra Varieties for Resistance to Okra Yellow Vein Mosaic Disease under Field Conditions

2021 ◽  
Vol 10 (1) ◽  
pp. ACCEPTED
Author(s):  
Sabir I. Khoso ◽  
Jamal-U-Ddin Hajano ◽  
Ali A. Lakho ◽  
Manzoor A. Abro ◽  
Khalid H. Dhiloo ◽  
...  
Keyword(s):  
Disease Severity ◽  
Significant Relationship ◽  
Growing Season ◽  
Mosaic Disease ◽  
Field Conditions ◽  
Yellow Vein ◽  
Growing Seasons ◽  
Vector Population ◽  
Yellow Vein Mosaic Disease ◽  
Disease Free

Okra (Abelmoschus esculentus L.) can contract okra yellow vein mosaic disease (OYVMD) caused by Bhendi yellow vein mosaic virus (genus: Begomovirus and family: Geminiviridae), vectored by whitefly (Bemisia tabaci). This study was carried out to screen okra varieties for resistance to OYVMD and to determine the correlation of vector population with the severity of the disease. Six varieties namely, Tulsi, Durgah, Sabz Pari, Sarahariya, Ramaan Kirshna and Pooja were grown under field conditions at localities of Shahpur, Tando Adam and Peer Kathi during rabi (winter cropping) and kharif (summer cropping) seasons during 2016 and 2017, respectively. The first incidence percent of the disease was recorded in the 8th week during rabi and the 6th week during kharif growing season. The Tulsi variety remained disease-free during both growing seasons. A significantly lower disease incidence % was recorded in Sabz Pari (29.32%) and Sarahariya (30.09%) varieties than Durgah, Ramaan Kirshna and Pooja during the rabi growing season. Both varieties were disease-free during the kharif season. There was remarkable variation in disease severity recorded in okra varieties at different trials during rabi and kharif seasons using a 0-6 rating scale (i.e., 0 = The disease-free plants, 1 = 1-10 % vein clearing, 2 = 11-25 % vein yellowing of small leaves , 3 = 26-50 % yellow network on some leaves, 4 = 51-60 % yellow network on all leaves, 5 = 60-70 % complete leaves turn yellow or cream color and 6 = 70 % plant stunted, deformed and small fruit and whole plants becomes colorless). Whitefly appeared in the 5th week during the rabi and 4th week during the kharif growing seasons. Vector population during the rabi growing season was significantly higher than in the kharif season. There was a nonsignificant relationship between disease severity and whitefly population in Ramaan Kirshna, Sarahariya, and Sabz Pari varieties. The disease severity in the Pooja variety showed a significant relationship with vector population, but only in the Tando Adam trial (R2= 0.7455, P= 0.0084), whereas the Durgah variety showed a significant relationship between disease severity and vector population in Shahpur (R2= 0.6615, P= 0.0267) and Tando Adam trials (R2= 0.8235, P= 0.0018). The same variety showed a nonsignificant relationship between disease severity and vector population in the Peer Kathi trial. It is concluded that Sabz Pari and Tulsi varieties are resistant to the disease

scholarly journals Growth Responses of Boreal Scots Pine, Norway Spruce and Silver Birch Seedlings to Simulated Climate Warming over Three Growing Seasons in a Controlled Field Experiment

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 943
Author(s):  
Katri Nissinen ◽  
Virpi Virjamo ◽  
Antti Kilpeläinen ◽  
Veli-Pekka Ikonen ◽  
Laura Pikkarainen ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Root Biomass ◽  
Growing Season ◽  
Silver Birch ◽  
Shoot Biomass ◽  
Growth Responses ◽  
Growing Seasons ◽  
Simulated Climate ◽  
Shoot And Root Biomass

We studied the growth responses of boreal Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst.) and silver birch (Betula pendula Roth) seedlings to simulated climate warming of an average of 1.3 °C over the growing season in a controlled field experiment in central Finland. We had six replicate plots for elevated and ambient temperature for each tree species. The warming treatment lasted for the conifers for three growing seasons and for the birch two growing seasons. We measured the height and diameter growth of all the seedlings weekly during the growing season. The shoot and root biomass and their ratios were measured annually in one-third of seedlings harvested from each plot in autumn. After two growing seasons, the height, diameter and shoot biomass were 45%, 19% and 41% larger in silver birch seedlings under the warming treatment, but the root biomass was clearly less affected. After three growing seasons, the height, diameter, shoot and root biomass were under a warming treatment 39, 47, 189 and 113% greater in Scots pine, but the root:shoot ratio 29% lower, respectively. The corresponding responses of Norway spruce to warming were clearly smaller (e.g., shoot biomass 46% higher under a warming treatment). As a comparison, the relative response of height growth in silver birch was after two growing seasons equal to that measured in Scots pine after three growing seasons. Based on our findings, especially silver birch seedlings, but also Scots pine seedlings benefitted from warming, which should be taken into account in forest regeneration in the future.

Smallseed Falseflax (Camelina microcarpa) Management in Oklahoma Winter Wheat

2021 ◽  
pp. 1-14
Author(s):  
Jodie A. Crose ◽  
Misha R. Manuchehri ◽  
Todd A. Baughman
Keyword(s):  
Winter Wheat ◽  
Weed Control ◽  
Herbicide Resistance ◽  
Wheat Yield ◽  
Acetolactate Synthase ◽  
Growing Season ◽  
Time Of Application ◽  
Adequate Control ◽  
Growing Seasons

Abstract Three herbicide premixes have recently been introduced for weed control in wheat. These include: halauxifen + florasulam, thifensulfuron + fluroxypyr, and bromoxynil + bicyclopyrone. The objective of this study was to evaluate these herbicides along with older products for their control of smallseed falseflax in winter wheat in Oklahoma. Studies took place during the 2017, 2018, and 2020 winter wheat growing seasons. Weed control was visually estimated every two weeks throughout the growing season and wheat yield was collected in all three years. Smallseed falseflax size was approximately six cm in diameter at time of application in all years. Control ranged from 96 to 99% following all treatments with the exception of bicyclopyrone + bromoxynil and dicamba alone, which controlled falseflax 90%. All treatments containing an acetolactate synthase (ALS)-inhibiting herbicide achieved adequate control; therefore, resistance is not suspected in this population. Halauxifen + florasulam and thifensulfuron + fluroxypyr effectively controlled smallseed falseflax similarly to other standards recommended for broadleaf weed control in wheat in Oklahoma. Rotational use of these products allows producers flexibility in controlling smallseed falseflax and reduces the potential for development of herbicide resistance in this species.

scholarly journals Rattail fescue (Vulpia myuros) interference and seed production as affected by sowing time and crop density in winter wheat

Weed Science ◽  
2020 ◽  
pp. 1-10
Author(s):  
Muhammad Javaid Akhter ◽  
Per Kudsk ◽  
Solvejg Kopp Mathiassen ◽  
Bo Melander
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Seed Production ◽  
Yield Components ◽  
Field Experiments ◽  
Growing Season ◽  
Sowing Time ◽  
Growing Seasons ◽  
Crop Density ◽  
Wide Range

Abstract Field experiments were conducted in the growing seasons of 2017 to 2018 and 2018 to 2019 to evaluate the competitive effects of rattail fescue [Vulpia myuros (L.) C.C. Gmel.] in winter wheat (Triticum aestivum L.) and to assess whether delayed crop sowing and increased crop density influence the emergence, competitiveness, and fecundity of V. myuros. Cumulative emergence showed the potential of V. myuros to emerge rapidly and under a wide range of climatic conditions with no effect of crop density and variable effects of sowing time between the two experiments. Grain yield and yield components were negatively affected by increasing V. myuros density. The relationship between grain yield and V. myuros density was not influenced by sowing time or by crop density, but crop–weed competition was strongly influenced by growing conditions. Due to very different weather conditions, grain yield reductions were lower in the growing season of 2017 to 2018 than in 2018 to 2019, with maximum grain yield losses of 22% and 50% in the two growing seasons, respectively. The yield components, number of crop ears per square meter, and 1,000-kernel weight were affected almost equally, reflecting that V. myuros’s competition with winter wheat occurred both early and late in the growing season. Seed production of V. myuros was suppressed by delaying sowing and increasing crop density. The impacts of delayed sowing and increasing crop density on seed production of V. myuros highlight the potential of these cultural weed control tactics in the long-term management programs of this species.

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

Kaolin impacts on hormonal balance, polyphenolic composition and oenological parameters in red grapevine berries during ripening

2021 ◽  
pp. 1-15
Author(s):  
Sara Bernardo ◽  
Lia-Tânia Dinis ◽  
Nelson Machado ◽  
Ana Barros ◽  
Marta Pitarch-Bielsa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Growing Season ◽  
Growing Seasons ◽  
Polyphenolic Composition ◽  
Berry Ripening ◽  
Hormonal Balance ◽  
Summer Stress ◽  
Fruit Damage ◽  
Stress Signals

BACKGROUND: Kaolin particle-film application is a well-known strategy to avoid fruit damage. However, its putative role in balancing berry ripening under a changing climate remains poorly explored. OBJECTIVE: We assessed kaolin treatment effect on several ripening berry components, hormonal balance and oenological parameters of the field-grown Touriga-Franca (TF) and Touriga–Nacional (TN) grapevine varieties at veraison (EL35) and ripening (EL38) during two growing seasons (2017 and 2018). RESULTS: Under the adverse summer conditions (two heatwave events) of 2017, kaolin application increased 211.2 %and 51.4 %the salicylic acid (SA) and abscisic acid (ABA) levels in TF berries at EL38, while no significant differences were observed in TN. Conversely, TF, and TN kaolin treated berries showed lower SA and ABA accumulation in 2018, respectively. Tartaric acid content increased about 17.2 %, and 24.2 %in TF and TN treated berries at stage EL35 in the 2017 growing season. Though kaolin treatment had no consistent effect on anthocyanins accumulation, flavonoids, ortho-diphenols and tannins increased in kaolin treated grapevines in 2017. CONCLUSIONS: This study highlights the key role of climate in triggering ripening related processes and fruit quality potential. Nevertheless, kaolin treated grapevines displayed an improved response to oxidative stress signals by increasing secondary metabolites accumulation in warm vintages. Kaolin application promoted different varietal responses, with a possible ripening delaying effect in TF, reinforcing its efficiency in alleviating severe summer stress impacts.

scholarly journals Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1726
Author(s):  
Nasr H. Gomaa ◽  
Ahmad K. Hegazy ◽  
Arafat Abdel Hamed Abdel Latef
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Stress Gradient ◽  
Growing Season ◽  
Annual Species ◽  
Negative Effects ◽  
Growing Seasons ◽  
Dry Seasons ◽  
The Impact ◽  
Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

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