Water relations of Pinusradiata in competition with weeds

1984 ◽  
Vol 14 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Roger Sands ◽  
E. K. Sadanandan Nambiar
Keyword(s):  
Productivity Loss ◽  
Radiata Pine ◽  
Stomatal Resistance ◽  
Tree Age ◽  
Weed Competition ◽  
Growing Seasons ◽  
Diurnal Patterns ◽  
Severe Water Stress ◽  
Soil Water Profiles ◽  
Needle Water Potential

Soil water profiles up to 2 m in depth and diurnal patterns of needle water potential and stomatal resistance were measured over a dry summer period in 5-, 16-, and 28-month-old radiata pine (Pinusradiata D. Don) plantations, growing with and without weed competition. Severe water stress with consequent productivity loss occurred in trees with weed competition but the severity of stress decreased progressively with increasing tree age. Transplanted seedlings in their first growing season had shallow root systems which could not efficiently exploit water at depth. By contrast, seedlings in their second and third growing seasons extracted water from at least a depth of 2 m. Trees without weed competition were not water stressed over this period even when planted at three times their normal stocking rate. Thus there is considerable capacity to increase early growth rates of radiata pine without water being the limit to growth if weeds are adequately controlled.

CROP-WEED COMPETITION STUDIES IN FABA BEAN (Vicia faba L.) UNDER RAINFED CONDITIONS

2001 ◽  
Vol 49 (3) ◽  
pp. 299-303 ◽  
Author(s):  
A. M. Tawaha ◽  
M. A. Turk
Keyword(s):  
Vicia Faba ◽  
Faba Bean ◽  
Yield Components ◽  
Field Experiments ◽  
Maximum Yield ◽  
Weed Competition ◽  
Growing Seasons ◽  
Yield And Yield Components ◽  
Vicia Faba L ◽  
Crop Weed Competition

Field experiments were conducted during the two growing seasons of 1999 and 2000 at the research farm of the Jordan University of Science and Technology (JUST) to study the effect of the time of weed removal on the yield and yield components of faba bean (Vicia faba L.). Removing weeds from 25 to 75 days after crop sowing led to significantly larger yields than on plots which were not weeded. Maximum yield was obtained in both years when weeds were removed thrice at 25, 50 and 75 days after crop sowing.

Daily and seasonal changes of water potential in cereals

1976 ◽  
Vol 273 (927) ◽  
pp. 565-580 ◽  
Keyword(s):  
Environmental Factors ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Leaf Age ◽  
Stomatal Resistance ◽  
Leaf Water ◽  
Wheat Crop ◽  
Growing Seasons ◽  
Winter Wheat Crop

The paper reports measurements of the water relations of a barley crop (cv. Proctor) and a winter wheat crop (cv. Maris Huntsman), grown on the same site at Sutton Bonington. Throughout the two growing seasons, days were chosen when hourly measurements could be made of leaf water potential, by means of a pressure chamber, and of stomatal resistance, by means of a diffusion porometer. Environmental factors, e.g. radiation, temperature, humidity, were recorded concurrently. Relationships between leaf water potential, stomatal resistance and environmental factors are explored and compared for the two cereals. In particular, as frequent measurements were made over two months, the influence of leaf age on responses to environmental factors can be examined. On selected days with bright sunshine and dry soil the response of both cereals to water stress is analysed with particular reference to the control of evaporation by stomatal closure

Effects of shoot pruning on stem growth, needle biomass, and dynamics of carbohydrates and nitrogen in Scots pine as related to season and tree age

1990 ◽  
Vol 20 (5) ◽  
pp. 514-523 ◽  
Author(s):  
B. Långström ◽  
O. Tenow ◽  
A. Ericsson ◽  
C. Hellqvist ◽  
S. Larsson
Keyword(s):  
Scots Pine ◽  
Linear Regression Analysis ◽  
Volume Growth ◽  
Early Summer ◽  
Tree Age ◽  
Stem Volume ◽  
Compensatory Mechanisms ◽  
Growing Seasons ◽  
Nitrogen Concentrations ◽  
Old Trees

In a field experiment in central Sweden, current shoots representing one-fifth of the needle biomass were removed from Scots pine (Pinussylvestris L.) by hand pruning young and old trees and by inducing Tomicuspiniperda (L.) (Coleoptera: Scolytidae) attacks on caged young trees. Branches in the uppermost whorls were pruned in later summer, early summer, or both. Starch and nitrogen concentrations in needles were monitored for two growing seasons. After four seasons the trees were felled and effects on growth were recorded. Starch and nitrogen concentrations in needles of pruned branches decreased and increased, respectively, compared with the controls. In old trees, but not in young ones, the raised nitrogen level persisted for 3 years after pruning. Starch and nitrogen concentrations in unpruned branches of pruned whorls did not change compared with the control until these branches became pruned, i.e., each branch acted as a semiautonomous integrated physiological unit. At felling, pruned trees were short of a portion of needle biomass equal to that removed, while at the same time, the needle biomass grown out above the pruned whorls was larger than the corresponding part of the controls. Stem volume losses in old hand-pruned trees were larger than and lasted longer than in young ones and were not yet completed four growing seasons after treatment. In a stepwise linear regression analysis, final needle biomass explained most of the total variation in volume growth of young hand-pruned trees, whereas for old trees, intertree competition was more important. Responses of beetle-pruned trees were similar to those of young hand-pruned trees. Differences in response to pruning and defoliation and in recovery between young and old trees are discussed in terms of source and sink theory and of compensatory mechanisms and carbohydrate limitation, respectively.

Determining the main and interactive effect of age and clone on wood density, microfibril angle, and modulus of elasticity for Pinus radiata

2010 ◽  
Vol 40 (8) ◽  
pp. 1550-1557 ◽  
Author(s):  
Michael S. Watt ◽  
Charles Sorensson ◽  
Dave J. Cown ◽  
Heidi S. Dungey ◽  
Robert Evans
Keyword(s):  
Pinus Radiata ◽  
Modulus Of Elasticity ◽  
Interactive Effect ◽  
Microfibril Angle ◽  
Wood Properties ◽  
Radiata Pine ◽  
Linear Increase ◽  
Interactive Effects ◽  
Tree Age ◽  
Clonal Variation

Detailed radial measurements of wood properties, taken at breast height, were obtained from control pollinated seedlings and a selection of 13 year old radiata pine ( Pinus radiata D. Don) clones. Using these data the key objectives of this study were to determine (i) the magnitude of mean clonal variation in modulus of elasticity (MOE) and properties affecting MOE (density and microfibril angle (MFA)) and (ii) whether there is a significant age × clone interaction for these traits. All wood properties were significantly affected by the main and interactive effects of age and clone. There was a relatively linear increase in both MOE and density with tree age, while MFA declined linearly with tree age. Values of density and MOE diverged between the clonal extremes from age 3 to age 12. After diverging markedly up to age 6, differences in MFA between clonal extremes remained relatively constant to age 12. At age 12, values for density, MFA, and MOE varied between clonal extremes by, respectively, 194 kg·m–3 (465–659 kg·m–3), 11.3° (9.6–20.9°), and 11.2 GPa (10.4–21.6 GPa). The seedling material had a relatively intermediate ranking, across the age range, for all traits considered.

Factors Associated with Establishment and Growth of Pinus coulteri and Pinus sabiniana in California’s Central Coast Bioregion

2019 ◽  
Vol 65 (6) ◽  
pp. 703-713
Author(s):  
Thomas Seth Davis ◽  
Miranda D Redmond ◽  
Nathaniel E Foote ◽  
William Miller
Keyword(s):  
Age Distribution ◽  
Ground Cover ◽  
Tree Age ◽  
Climate Signal ◽  
Cone Production ◽  
Factors Associated ◽  
Growing Seasons ◽  
Growth Increments ◽  
High Vapor ◽  
Pinus Coulteri

Abstract Forest inventory indicated recent decline in a P. coulteri population at its northern extent but live stems in sympatric P. sabiniana increased. Patterns of cone production, localized factors associated with regeneration, relations between wildfire and tree age distributions, and correlations between climate, seedling establishment, and tree growth were analyzed as potential mechanisms underlying unequal demographics between the two species. Four findings emerged: (1) P. sabiniana had a higher frequency of open cones at the time of observation, but cone production was size-biased, and cone production rates were similar for both species; (2) P. sabiniana seedlings were associated with a higher proportion of bare ground cover and westerly aspects, whereas establishment of P. coulteri seedlings was correlated with warm growing seasons and high vapor-pressure deficits, and seedlings occurred on northernly aspects; (3) age distributions of stands inside and outside a wildfire perimeter did not differ for either species, but annual growth increments of P. coulteri were greater within the fire perimeter; and (4) P. coulteri was even-aged, establishment was episodic, and occurred approximately 10 years post-wildfire. In contrast, the age distribution of P. sabiniana was highly variable, consistent with continuous recruitment, and establishment was not correlated with a climate signal.

scholarly journals Soil Disturbance Impacts on Early Growth and Management of Radiata Pine Trees in New Zealand

2004 ◽  
Vol 19 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Glen Murphy ◽  
John Firth
Keyword(s):  
Penetration Resistance ◽  
Radiata Pine ◽  
Soil Disturbance ◽  
Weed Competition ◽  
Early Management ◽  
Precommercial Thinning ◽  
Soil Penetration Resistance ◽  
Disturbed Areas ◽  
Pine Trees ◽  
Volume Measurements

Abstract In the mid-1980s, trials were established in Esk and Ngaumu Forests to determine the effect of five graded levels of skid trail usage (i.e., logging-induced soil disturbance) on the growth and early management of the next crop of trees. This article reports results of measurements taken up until the Esk trees were 16 years old and the Ngaumu trees were 14 years old. Soil disturbance influenced both soil penetration resistance and weed competition; soil penetration resistance was greatest on the heavily disturbed areas, and weed competition was greatest on the undisturbed areas. Up until the time when the trees were first precommercially thinned, there was no clear relationship between disturbance levels and tree malformation. Only heavily disturbed areas in the Ngaumu trial showed increased levels of mortality. Fastest height and diameter growth occurred on minor skid trails where a certain amount of soil disturbance had taken place. Trees on completely undisturbed sites grew almost as poorly as those on the most disturbed areas (major skid trails). This difference was still evident in tree volume measurements at mid-rotation; i.e., about 15 years old. Soil disturbance also influenced the early management of the trees. Heavily disturbed areas had fewer trees selected for low pruning and more trees selected for precommercial thinning. West. J. Appl. For. 19(2):109–116.

Effects of drought stress and severe pruning on the reaction zone induced by single inoculations with a bark beetle associated fungus (Ophiostoma ips) in the phloem of young Scots pines

1998 ◽  
Vol 28 (12) ◽  
pp. 1814-1824 ◽  
Author(s):  
Luc Croisé ◽  
Erwin Dreyer ◽  
François Lieutier
Keyword(s):  
Water Stress ◽  
Reaction Zone ◽  
Bark Beetle ◽  
Severe Water Stress ◽  
Reaction Zones ◽  
Maximum Water ◽  
Ips Sexdentatus ◽  
Effects Of Drought ◽  
Two Parameters ◽  
Needle Water Potential

The objective of this study was to test the effect of water stress and pruning on the resistance of young Scots pines (Pinus sylvestris L.) to a bark beetle associated fungus. Six-year-old potted trees were either pruned (70% of needles removed) or subjected to several successive episodes of severe water stress, prior to inoculation of inner bark with the fungus Ophiostoma ips (Rumb.) Nannf., which is usually associated with the bark beetle Ips sexdentatus Boern. Well-watered, nonpruned trees served as controls. Predawn needle water potential reached -2.5 MPa and net CO2 assimilation rates were reduced to almost zero during each water stress episode. The length of the reaction zones around inoculation points reached 3-4 cm after 3 weeks. It was higher during Spring than during Autumn. Impact of water stress on the length of the reaction zone was very limited and independent of the number of drought episodes that had been imposed prior to inoculation. The only visible change was a slight decrease when the inoculation was done during the period of maximum water stress intensity. Growth of the pathogen in the phloem was not affected by water stress. Correspondingly, pruning had no effect on either of these two parameters. Induced reaction zones accumulated monophenolic compounds that were undetectable in unwounded phloem. These included pinocembrin and pinosylvin and its monomethylether known to contribute to the defence against the fungus. Neither drought nor severe pruning induced any change in the nature or concentrations of these compounds in the unwounded phloem or in the reaction zone.

scholarly journals Weed-Crop Competition in Pigeon Peas in Puerto Rico

1969 ◽  
Vol 69 ◽  
pp. 201-213
Author(s):  
Manuel Díaz-Rivera ◽  
Paul R. Hepperly ◽  
Guillermo Riveros ◽  
Luis Almodóvar-Vega
Keyword(s):  
Puerto Rico ◽  
Pigeon Pea ◽  
Crop Growth ◽  
Weed Competition ◽  
Growth Stages ◽  
Southern Plains ◽  
Growing Seasons ◽  
Delayed Differentiation ◽  
Weed Flora ◽  
Planting Season

Kaki and 28-Bushy pigeon peas were grown in the southern plains of Puerto Rico, in four spatial arrangements with six intervals of weed competition during two growing seasons to determine the influence of weed competition on crop growth, development and yield. In both growing seasons, Cleome gynandra, Amaranthus dubius, Echinochloa colona, Leptochloa filiformis, and Digitaria sanguinalis were the dominant weeds. C. gynandra and E. colona dominated the early weed flora until approximately 40 days after pigeon pea emergence. Later, weed flora was dominated by L. filiformis, D. sanguinalis, and A. dubius. The presence of weeds during early growth stages reduced initial crop growth and delayed differentiation including flowering of the two pigeon pea cultivars. Elimination of weeds at or before 21 to 28 days after pigeon pea emergence and thereafter, generally resulted in the recovery of pigeon pea plants and prevented measurable losses in final yield. The critical period for removing weeds in pigeon peas appeared to vary between the pigeon pea cultivars and between the two growing seasons. In the May 6 planting, pigeon pea yields were reduced after 28 and 21 days of early competition for Kaki and 28-Bushy, respectively. In the July 1 planting, however, losses occurred at 21 and 14 days of weed competition for the two respective cultivars. No differences were found in weed numbers or yield between the two cultivars or among spatial arrangements in either planting season. However, weed number and yield were greater during the first planting season compared with those of the second. Planting pigeon peas under short photoperiods accelerated vegetative growth, shortened the total cropping cycle, and resulted in reduced yield and total growth for both cultivars. Losses from early weed competition occurred earlier under the short-day planting than those under the long-day planting.

scholarly journals (58) Evaluation of Select Perennial Ornamental Cultivars for Potential Roadside Beautification Application

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1042B-1042
Author(s):  
Rodulfo O. Pacumbaba ◽  
Catherine Sabota ◽  
Rhonda Britton
Keyword(s):  
Mortality Rate ◽  
Significant Interaction ◽  
Repeated Measurements ◽  
Weed Competition ◽  
Evaluation Period ◽  
Knock Out ◽  
Growing Seasons ◽  
Recovery Potential ◽  
Agnus Castus ◽  
Experimental Plots

Sixty-six perennial ornamental cultivars were established and then grown under low maintenance, intensive weed competition, and severe mowing conditions. These cultivars were evaluated for their potential application for roadside/median beautification. Experimental plots were cleared with Roundup® prior to planting. During the first 3 weeks of establishment, plants were irrigated as needed. Plants were grown for one season, then pruned back to simulate bush-hog mowing. Plants were grown under low maintenance and no weed control conditions for two growing seasons. Plants were evaluated each season for simulated bush-hog damage recovery potential, survivability under severe weed competition, height, and spread. Two-way analysis of variance with repeated measurements showed that height and spread variation had a significant interaction between plant cultivar and time of evaluation. Several Zephyranthes sp. cultivars performed poorly under severe weed competition and mowing damage resulting in a high mortality rate. Cultivars that did perform well for the 2-year evaluation period include Lagerstroemia indica ×fauriei `Natchez,' Lagerstroemia indica ×fauriei `Muskogee,' Vitex agnus-castus `Shoal Creek,' and Myrica cerifera. Rosa × `Chuckles' and Rosa × `Knock Out' cultivars, with their popular showy appearance, performed moderately well and showed high potential for roadside/median beautification applications.

Responses of radiata pine clones to varying levels of pasture competition in a semiarid environment

1999 ◽  
Vol 29 (7) ◽  
pp. 934-939 ◽  
Author(s):  
E G Mason ◽  
B Kirongo
Keyword(s):  
New Zealand ◽  
Coefficient Of Variation ◽  
Genetic Effect ◽  
Radiata Pine ◽  
Competitive Environment ◽  
First Year ◽  
Weed Competition ◽  
Variable Response ◽  
Semiarid Environment ◽  
Four Levels

An experiment comprising seven clones with four levels of weed competition was established on a semiarid site on the Canterbury plains, New Zealand, during September 1996. Previous experiments showed that trees subjected to little competition from weeds did not always respond to their favourable environments, resulting in more variation among individuals subjected to less competition. The aim of this experiment was to determine whether the variable response to competitive environment is partly a genetic effect. The main plots consisted of four levels of competition: no competition and cleared spots: 3.14, 0.75, and 0.03 m2. Within each plot there were 10 individuals of each clone. Trees generally grew more rapidly with increasing amounts of clear ground, but increasing spots beyond 3.14 m2 did not increase growth during the first year. Variation, expressed as coefficient of variation, was greater among trees subjected to more competition. Within clone coefficient of variation was not related to level of competition.

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