Seasonal Vegetation Growth Research Articles

Effect of β grain size on mechanical properties of lamellar microstructures in Timetal-1100 : Berg, A., Kiese, J. and Wagner, L. Conference: Light Weight Alloys for Aerospace Applications III, Las Vegas, Nevada, USA (13–16 Feb. 1996)

Aldicarb, 2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxime, is a systemic insecticide used extensively for early season insect control in cotton (Gossypium hirsutum L.). The indirect effect of aldicarb on cotton due to insect control is well documented; however, much less is known regarding its direct effect on cotton growth and development. The purpose of this research was to test the hypothesis that aldicarb in the absence of insects imposes a direct effect on cotton growth and that aldicarb effectiveness on growth depends on temperature. Cotton plants (cv. Deltapine-50 and DES-119) were grown in outdoor sunlit plant growth chambers under five day/night temperatures (20/12, 25/17, 30/22, 35/27, and 40/32 °C). In one study, aldicarb at 0.56 kg ha−1 was applied to soil at sowing. In a second study, aldicarb was first applied at a rate of 0.84 kg ha−1 to soil at sowing and applied again at a rate of 2.24 kg ha−1 at the stage of flower bud initiation as a side-dressing. Aldicarb increased early season vegetative growth of cotton plants grown at 25/17, 30/22, and 35/27 °C, but not for plants grown at 20/12 and 40/32 °C. Aldicarb also promoted the early formation of cotton flower buds at the five temperature regimes and increased the number of flowers at 30/22 °C. The treated plants had more growing roots, greater root length densities in the 61–80 cm soil depth, and higher root/shoot ratios than control plants at all temperatures. Our results showed that aldicarb promoted cotton earliness by enhancing growth rates and promoting the roots to grow deeper into soil. The responses of cotton to aldicarb depended on temperature, with a greater effect occurring at near optimum temperatures for cotton growth.

Growth responses of cotton to aldicarb and temperature

Aldicarb, 2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxime, is a systemic insecticide used extensively for early season insect control in cotton ( Gossypium hirsutum L.). The indirect effect of aldicarb on cotton due to insect control is well documented; however, much less is known regarding its direct effect on cotton growth and development. The purpose of this research was to test the hypothesis that aldicarb in the absence of insects imposes a direct effect on cotton growth and that aldicarb effectiveness on growth depends on temperature. Cotton plants (cv. Deltapine-50 and DES-119) were grown in outdoor sunlit plant growth chambers under five day/night temperatures (20/12, 25/17, 30/22, 35/27, and 40/32 °C). In one study, aldicarb at 0.56 kg ha −1 was applied to soil at sowing. In a second study, aldicarb was first applied at a rate of 0.84 kg ha −1 to soil at sowing and applied again at a rate of 2.24 kg ha −1 at the stage of flower bud initiation as a side-dressing. Aldicarb increased early season vegetative growth of cotton plants grown at 25/17, 30/22, and 35/27 °C, but not for plants grown at 20/12 and 40/32 °C. Aldicarb also promoted the early formation of cotton flower buds at the five temperature regimes and increased the number of flowers at 30/22 °C. The treated plants had more growing roots, greater root length densities in the 61–80 cm soil depth, and higher root/shoot ratios than control plants at all temperatures. Our results showed that aldicarb promoted cotton earliness by enhancing growth rates and promoting the roots to grow deeper into soil. The responses of cotton to aldicarb depended on temperature, with a greater effect occurring at near optimum temperatures for cotton growth.

A Comparison of Scenarios for the Effect of Global Climate Change on Cotton Growth and Yield

If global surface temperatures change as projected because of radiative and physiological effects of a changing environment, we should expect important changes in crop production in the 21st Century. Experiments were conducted at ambient and twice ambient atmospheric CO2 concentrations at five temperatures. The 1995 temperature in Mississippi was used as a reference with the other temperatures being 1995 minus 2˚C, and 1995 plus 2, 5 and 7˚C. Daily and seasonal variation and amplitudes were maintained. Seedlings had 4–6 times as much leaf area and dry weight at 20 d after emergence when grown at 28˚C as at 23˚C (1995 ambient) average temperature during that growth period. Number of days to first square, flower, and open boll decreased as temperature increased. Double atmospheric CO2 did not affect these developmental rates. Temperatures above 28˚C, or 1995 average whole-season temperatures, were detrimental to mid- and late-season boll retention and growth. No fruits were retained to maturity at 1995 plus 5 or 7˚C. However, whole season vegetative growth was not significantly reduced by temperature 5–7˚C above the 1995 ambient conditions. Twice ambient CO2 caused about 40% increase in vegetative dry matter accumulation across temperatures. In a separate experiment, similar results were obtained on fruiting cotton grown at a range of temperatures based on long-term average US Midsouth July temperatures. Therefore, if global warming occurs as predicted, food and fibre production in such high-temperature and humid environments may be more limited to vegetative structures and the animals that consume vegetative structures.

Predicting Stage-Discharge Curves in Channels with Bank Vegetation

Many flood-control channels are subjected to expensive and environmentally damaging maintenance practices to control vegetation growth in attempts to preserve flood capacity. However, such maintenance regimes are often based on vague and qualitative guidelines. There is a clear need for physically based methods of predicting the impacts of vegetation growth on flow resistance and flood capacity. In the present note, a numerical hydraulic model is coupled with physically based flow-resistance equations for gravel-bed materials and vegetation roughness elements. The resulting model is capable of simulating stage-discharge curves in channels with arbitrary cross-section geometry, gravel-bed materials and bank, and/or flood-plain vegetation, including overbank flows. The new model is demonstrated to be capable of closely replicating the stage-discharge curve at a study site on a natural river channel. Finally, the model is demonstrated using examples in which the effects on flood capacity of seasonal vegetation growth are simulated at the study site.

Predicting Influence of Bank Vegetation on Channel Capacity

A theoretically based method for taking into account the effects of bank vegetation on channel-flow parameters is outlined. It can be used to predict what effect changes in bank vegetation will have on the discharge capacity of a channel and to make comparisons of bank-vegetation effects between channels. Using the analysis on individual channels may aid in gauging the true impact of bank vegetation on in-bank flow capacity and in deciding whether the beneficial effects of bank vegetation in stabilizing banks outweigh any adverse effects that result from the potential reduction in discharge capacity. Using this method, the effect bank vegetation has on channel discharge capacity is shown to decline rapidly as the width-to-depth ratio of channels increases. When seasonal growth of vegetation is simulated the effect on channel discharge capacity is shown to be less than 10% for channels with a width-to-depth ratio greater than 16.

Carbon and Nitrogen Economy of Developing Rabbiteye Blueberry Fruit

Carbon dioxide exchange, dry weight, C, and N content of `Bonita' and `Climax' blueberry (Vaccinium ashei Reade) fruit were measured from anthesis through fruit ripening to quantify developmental changes in amounts of imported C and N required for fruit development. Net photosynthesis occurred in fruit of both rabbiteye cultivars from petal fall through color break. During this time, fruit net photosynthesis declined from 16 μmol CO2/g fresh weight (FW) per hour for `Bonita' and 22 μmol CO2/g FW per hour for `Climax' to 0.2 μmol CO2/g FW per hour for both. Dark respiration for both cultivars declined following petal fall from 16 μmol CO2/g FW per hour to 3 μmol CO2/g FW per hour before increasing at fruit ripening to 9 μmol CO2/g FW per hour. Fruit C content was constant at 0.43 mg C/mg dry weight (DW) throughout development, while N content declined from 0.05 mg N/mg DW at petal fall to 0.01 mg N/mg DW at ripeness. DW accumulation and respiration accounted for 63% and 37%, respectively, of the total C requirement for fruit development. Fruit photosynthesis was estimated to contribute 15% of the total C required for fruit development in both cultivars; however, fruit photosynthesis supplied 50% of the C required during the first 10 days after bloom and 85% during the 5 days after petal fall. This large, early contribution of C from fruit photosynthesis may aid in the establishment of fruit until the current season's vegetative growth can supplement plant carbohydrate reserves in providing C for fruit development.

On the Adaptive Value of Physiological Integraton in Colonal Plants

In clonal plants, genetically identical ramets arise from a common stolon or rhizome. Anatomical connection often allows physiological integration, the translocation of resources from a larger mother ramet to a developing daughter ramet. Translocation of a limiting resource can reduce the mother's growth while increasing the daughter's growth. Our models predict patterns in resource translocation; the models assume that fitness increases with the expected biomass a genet attains over a season of vegetative growth in a stochastic environment. In each model a ramet's growth depends nonlinearly on its level of a limiting resource. If resource availability varies both spatially and temporally, and a ramet's growth does not depend on its size, an analytical approximation for total genet growth leads to several new predictions. If a ramet's growth increases as a concave function (i.e., a function with decreasing positive slope) of resources level, physiological integration should increase when spatial variance increases and spatial convariance is negative. If a ramet's growth increases as a convex function (increasing positive slope) of resource level (the less likely case), spatial variance—convariance in resource availability has the opposite effect on translocation. Independently of the concavity or convexity of the growth function, increasing temporal variance in the mother ramet's resource availability reduces translocation, and increasing temporal variance in the daughter ramet's resource availability increases translocation. When a ramet's growth increases with both its resource level and its size, translocation and growth in one time interval influence the value of future physiological integration. For this case a stochastic dynamic programming model demonstrates how translocation can depend on time and the sizes of the mother and daughter ramets, as well as on spatiotemporal resource variability. The predictions qualitatively match those deduced from the model of size—independent growth, although translocation often declines late in the season of vegetative growth. The dynamic model also indicates that a large mother ramet should always share resource with a daughter ramet. But a smaller mother ramet should often abandon a daughter and allocate all its available resource to its own growth.

PHOTOSYNTHESIS, RESPIRATION, AND CARBON COST OF DEVELOPING RABBITEYE BLUEBERRY FRUIT

Carbon exchange and content of blueberry (Vaccinium ashei) fruit were measured from anthesis through fruit ripening in order to determine the amount of imported carbon required for fruit development. Net photosynthesis occurred in blueberry fruit from petal fall through color break. During this time, gross photosynthesis of fruit decreased from 30.1 μmol CO2·g fw-1·hr-1 to 4.8 μmol CO2·g fw-1·hr-1, and dark respiration decreased from 14.3 μmol CO2·g fw-1·hr-1 to 4.6 μmol CO2·g fw-1·hr-1. After color break, the photosynthetic rate fell to zero, and the respiration rate increased to 8.0 μmol CO2·g fw-1·hr-1, before decreasing. Preliminary data suggest that fruit photosynthesis contributes 11% of the total carbon required (dry weight gain + respiratory loss) during fruit development however, it supplies 50% of the total carbon required during the first 5 days after petal fall. This contribution of carbon from fruit photosynthesis may be critical in initial fruit development since the current season's vegetative growth is not yet providing carbohydrates.

PHOTOSYNTHESIS, RESPIRATION, AND CARBON COST OF DEVELOPING RABBITEYE BLUEBERRY FRUIT

Carbon exchange and content of blueberry (Vaccinium ashei) fruit were measured from anthesis through fruit ripening in order to determine the amount of imported carbon required for fruit development. Net photosynthesis occurred in blueberry fruit from petal fall through color break. During this time, gross photosynthesis of fruit decreased from 30.1 μmol CO2·g fw-1·hr-1 to 4.8 μmol CO2·g fw-1·hr-1, and dark respiration decreased from 14.3 μmol CO2·g fw-1·hr-1 to 4.6 μmol CO2·g fw-1·hr-1. After color break, the photosynthetic rate fell to zero, and the respiration rate increased to 8.0 μmol CO2·g fw-1·hr-1, before decreasing. Preliminary data suggest that fruit photosynthesis contributes 11% of the total carbon required (dry weight gain + respiratory loss) during fruit development however, it supplies 50% of the total carbon required during the first 5 days after petal fall. This contribution of carbon from fruit photosynthesis may be critical in initial fruit development since the current season's vegetative growth is not yet providing carbohydrates.

Influence of male cones on early season vegetative growth of Pinus contorta trees.

On average, branches of Pinus contorta Dougl. bearing male cones had 35 fewer needle pairs than equivalent vegetative branches, and significantly fewer differentiated primordia (i.e., male cones + needle pairs + sterile cataphylls). It was estimated that the formation of male cones results in a 27-50% reduction in the number of needles per male cone-bearing branch. In early spring, branches bearing male cones had on average 23% (0.44 g) more dry weight than vegetative branches. On average, 95% of the dry weight of male cone-bearing branches was allocated to the terminal shoot (54% of which was male cones) and 5% to the lateral shoots. By comparison, vegetative branches allocated 85% of their total dry weight to the terminal shoot and 15% to the lateral shoots. These findings suggest that male cones may reduce the photosynthetic potential of the trees which bear them.

Water requirement, yield and fruit quality of grapefruit irrigated with high-sulphate water

SummaryThe effect of irrigation with different amounts of high-sulphate water on the growth and yield of grapefruit trees was studied during a six-year period. Irrigation with 600–700 mm of water over the irrigation season, corresponding to 50–60% of pan evaporation, proved sufficient for high yield. Under-irrigation increased soil salinity associated with the highly soluble salts, and reduced tree growth (girth increase and seasonal vegetative growth). Although the fruit growth of the stressed grapefruit trees was delayed and yield was reduced, total soluble solids and acid percentage of the juice were increased significantly. Irrigation with the higher amounts of high-sulphate water resulted in gypsum precipitation/dissolution and a low persistent soil salinity which could not be leached.

Canopy Development, Yield, and Market Quality in Peanut as Affected by Genotype and Planting Pattern

Planting peanut (Arachis hypogaea L.) in narrow rows with greater spacing between plants in order to approach a square pattern of plant arrangement can reduce competition and increase growth, especially during juvenility. Thus, this study was designed to assess the effects of planting pattern, genotype, and their interaction on seasonal vegetative growth, fruit growth and development, pod and kernel yields, and market quality. Seven genotypes, ‘Florunner’, ‘Tamnut’, and five experimental lines were used. Planting patterns (interrow × intrarow spacing) of narrow row (0.46 × 0.15 m), row [(0.69−0.23) × 0.15 m], and conventional row (0.91 × 0.08 were each established at 15 plants m−2 (150 000 ha−1) in mid‐April of 1985 and 1986. The soil was an Arreodondo loamy sand (loamy, siliceous, hyperthermic, Grossarenic Paleudult) on The Agronomy Farm located near Gainesville, FL. Plots were 6.1 m long and three rows wide (conventional) or four rows wide (narrow and twin row). Florunner, Tamnut, and line 84‐516 from the seven genotypes were sampled biweekly for growth analysis. Plants in the narrow‐ and twin‐row planting patterns, compared to the conventional, had significantly greater ground cover, leaf area indices, canopy light interception, crop growth rates, and yields of total dry matter, pods, and kernels. Planting pattern had no significant effect (P > 0.05) on market quality. Florunner and Tamnut were superior to the experimental lines in growth and kernel yield. Planting pattern and genotype interaction effects on pod and kernel yields were not significant. We conclude that planting patterns that approach equidistant spacing or a square arrangement can produce higher pod and kernel yields than conventional (wide) rows. Furthermore, either narrow‐ or conventional‐row patterns are suitable for screening or testing genotypes of diverse growth habit and market type.

Influence of Growth Retardants (Anti‐Gibberellins) on Corn Vegetative Growth, Water Use, and Grain Yield under Different Levels of Water Stress1

AbstractCorn (Zea mays L.) grown under the semiarid conditions of the Central Great Plains requires supplemental irrigation to obtain maximum yields. This practice has become increasingly less profitable as the cost of application of irrigation water has risen. It may prove to be more cost effective to reduce the water requirement of corn by limiting the vegetative development of the plant. Two anti‐gibberellin, seed‐applied, experimental plant growth regulators (PGRs), BAS 106. .W and BAS 110. .W, were used on corn grown under low and high levels of irrigation in a 2‐yr (1984 and 1985) field study on a Rago silt loam soil (fine, montmorillonitic, mesic Pachic Argiustolls) to determine the effect of these PGRs on vegetative growth, water use, water stress, grain yield, and yield components. The PGRs were applied at three rates in both years (0, 100, and 200 mg a.i. kg−1 of BAS 106. .W in 1984 and 0, 125, and 250 mg a.i. kg−1 of BAS 110. .W in 1985). Increasing application rates of the PGRs caused a significant reduction in early season plant height, leaf area index (monitored in 1985 only), and dry matter accumulation (monitored in 1985 only), resulting in reduced early season evapotranspiration in both years. The PGR treatments reduced plant water stress during silking and early grain fill, particularly under the low irrigation treatment. The changes in plant growth and development associated with the PGRs resulted in a 9 and 16% increase in grain yield in 1984 and 1985, respectively, under the low irrigation treatment and a 7 and 9% reduction in grain yield in 1984 and 1985, respectively, under the high irrigation treatment. Therefore, reducing early season vegetative growth with the PGRs proved to be advantageous to productivity under water stress and counterproductive under nonlimiting water conditions.

Comparative Growth of Obsolete and Modern Cotton Cultivars. III. Relationship of Yield to Observed Growth Characteristics1

Yield differences among cotton (Gossypium hirsutum L.) lines have been used as the measure of cultivar suitability in this century. The result has been a steady increase in yields as progressively newer cultivars have been developed, while little or no information pertaining to the alterations in growth responsible for the enhanced performance has been collected. To assess the association of growth response to lint yield, 12 cotton cultivars representing release years since 1900 were examined for yield, yield components, and their relationship to seasonal vegetative and reproductive growth patterns resulting from two planting dates during 1982. The observed yield of lint exhibited a linear increase in association with the increased year of cultivar release. The largest contributor to yield variation was the number of bolls produced. The modern cultivars (since 1950) produced a greater proportion of their total lint and boll number before 135 days after planting. The early lint production of these cultivars is associated with smaller vegetative plant canopies and an earlier transition to reproductive growth. The modern cultivars exhibited smaller boll weights and a greater lint percentage. Fiber quality, with the exception of micronaire, showed little improvement due to plant breeding. Micronaire tended to increase in the newer cultivars. The data indicate that breeding efforts have altered the number of harvestable bolls to a greater extent than any other characteristic.

A SPATIALLY RESPONSIVE HYDROLOGIC MODEL TO PREDICT EROSION AND SEDIMENT TRANSPORT1

ABSTRACT: A finite element numerical model has been developed by the authors which routes overland and channel flows in a watershed, given soils, land use, topographic descriptors, and rainfall as input. Such processes as infiltration, canopy interception, seasonal growth of vegetation, and depression storage are described in the hydrologic context of the model. These capabilities, along with the spatial detail and responsiveness of the model, allow a ready adaptation of the model to provide for the prediction of sediment transport and yield.It is assumed that the best results can be obtained by a technique which utilizes the following procedures. Sediment yield to the channel is described by functions describing soil detachment by rainfall and overland flow and transport by overland flow. Since the model description of the channel flow processes involves a more realistic representation of the physical drainage system, an attempt was made to define sediment transport in the channel by erosion and sedimentation mechanics.A conceptual framework is provided whereby the integrated effects of various land use activities on sediment transport and yield can be evaluated. Inherent in this provision of the model is the capability of determining the effects of any control measures to be implemented on a watershed.

Phragmites performance in reed beds in the Tay Estuary

SynopsisAn extensive reed bed on the north shore of the inner Tay Estuary is briefly described. Studies in the summers of 1975, 1976 and 1978 showed it to comprise monodominant stands of Phragmites communis Trin. The standing crop of shoots was sampled at the end of the season of vegetative growth and analysed by simple biometrical methods. Certain important spatial and architectural characteristics of the community varied in a regular manner with position in the bed. Estimates of the above ground productivity of intact stands ranged from 100 to 150 tonnes/ha in a poor growing season. Commercial harvesting operations, conducted since 1975, produced an immediate and consistent decrease in shoot stature, apparently followed by a slow increase in density and productivity. The behaviour of the downshore edge of the bed and the details of its annual development above and below ground require further study.

Growth and Development of Highbush Blueberry. I. Vegetative Growth

Abstract The seasonal vegetative growth sequences of the highbush blueberry (Vaccinium corymbosum Ait.) and certain features, including apical abortion, are described during growth under usual conditions and under the influence of succinic acid-2,2-dimethylhydrazide (daminozide) sprays. Apical abortion, followed by chlorosis and necrosis of the distal portion of the shoot is a natural phenomenon in highbugh blueberry and results in episodic, sympodial extension growth. Daminozide sprays did not substantially alter the abortion pattern, though shoot growth was substantially reduced the first year of spray application. Shoot growth was not significantly reduced in bushes sprayed but not pruned for 2 years.