Rate Of Leaf Production Research Articles

Effects of Carbon Dioxide Enrichment on the Expansion and Size of Kudzu (Pueraria lobata) Leaves

Seedlings of kudzu were grown at 350, 675, or 1000 μl/L CO2in controlled-environment chambers. At elevated CO2concentrations, maximum leaf expansion rates were approximately 40% greater, leaves were fully expanded several days sooner, fully expanded leaves were larger at each leaf position, and leaf production rates were increased 12%. Peak starch accumulation was much greater in plants grown at elevated CO2concentrations. Total xylem water potentials were higher (less negative) at full hydration, and osmotic potentials were decreased (more negative) by CO2enrichment. At 1000 μl/L CO2, leaf turgor pressure was twice that at 350 μl/L CO2. Results suggest that leaf expansion rates and leaf expansivity may have been increased due to higher turgor pressure at the higher CO2concentrations. The potential for successful seedling establishment may be enhanced as the atmospheric CO2concentration continues to rise, increasing kudzu invasiveness.

Response of orchard 'Washington Navel' orange, Citrus sinensis (L.) Osbeck, to saline irrigation water. I. Canopy characteristics and seasonal patterns in leaf osmotic potential, carbohydrates and ion concentrations

Effects of irrigation water salinity on tree canopy volume, leaf area, rates of leaf abscission and production, as well as seasonal patterns in leaf osmotic potential (=), starch, soluble sugars and sodium and chloride concentrations were determined for 24-year-old 'Washington Navel' orange trees (Citrus sinensis [L.] Osbeck) on sweet orange (C. sinensis) rootstock. Trees had been irrigated with water containing either 5 or 20 mol NaCl m-3 for 5 years prior to measurements.Trees irrigated with 20 mol NaCl m-3 had a greater number of vegetative flushes in spring. This occurred at the expense of flowering, as numbers of reproductive and mixed flushes were reduced by salinity. Despite a high number of vegetative buds on trees irrigated with 20 mol NaCl m-3, leaf area was still less than low salinity trees.Extensive abscission of spring flush leaves occurred from mid-summer onwards for trees irrigated with 20 mol NaCl m-3. This was not a consequence of leaf water deficit, as more negative leaf osmotic potentials resulting from increased foliar sodium and chloride concentrations resulted in maintenance of leaf turgor. Excessive concentrations of sodium and/or chloride may have been responsible for abscission observed. Some acclimation of foliage to salinity was evident.Irrespective of salinity treatment, leaf osmotic potential became more negative as the season progressed. This was partly due to increased concentrations of soluble sugars in foliage during autumn and winter. Levels of soluble sugars and starch were consistently lower in leaves on trees irrigated with high salinity water, indicating that production rather than utilization of carbohydrate may limit citrus productivity under saline conditions.

Growth characteristics of a recommended cassava cultivar, Rayong 3, in Thailand.

Growth characteristics of Rayong 3, a recommended cultivar with sparse branching habit, were compared with those of Rayong 1, a traditional cultivar with tall and erect stems. Root production was largely influenced by the total dry matter production during the rainy season which was closely associated with a leaf area index (LAI). Rayong 3 showed some advantages in root production when compared with Rayong 1; i) high dry matter production during the rainy season, which was associated with a high LAI due to mainly the high leaf production rate per plant, ii) a high harvest index and iii) high dry matter and starch contents of storage roots. A moderate branching habit, represented by Rayong 3, could maintain a high harvest index when the total dry matter production and leaf area incrcased under the prevailing growth conditions of cassava in Thailand.

Joint action of sulfur dioxide and hydrogen fluoride on growth of Eucalyptus tereticornis

Eucalyptus teriticornis plants were continuously exposed to SO 2 (< 13,130 and 267 μg/m 3), HF (< 0.06 and 0.38 μg/m 3) or their combination for 90 days in open-top chambers when the plants were 18 months old. The effect of these treatments was a change in the pattern of growth. HF or SO 2 alone reduced leaf surface area and weight in mature and immature leaves. Plants exposed to 130 μg/m 3 of SO 2 may have compensated for reduced leaf area and weight by increasing leaf chlorophyll concentrations and leaf production rate. Treatment with the combination of HF and SO 2 reduced the area and weight of mature leaves, and resulted in higher leaf fluoride concentrations than those exposed to HF alone, possibly as a result of increased stomatal conductance.

Temperature-dependent feedback inhibition of photosynthesis in peanut

Arachis hypogaea L. is a tropical crop that is slow-growing at temperatures below 25°C. Unadapted CO2-assimilation rate (A) showed insufficient variation between 15 and 30°C in the short term (hours) to explain this marked reduction in growth. However, at longer periods (12 d), A was depressed as were growth rate and leafproduction rate. To examine the possible relationship between growth, A and sink demand plants were transferred from 30°C, which is near the optimum for growth, to a suboptimal temperature (19°C). In the first 2 d of cooling, A decreased by 50-70%, the stomata stayed open, and the intercellular CO2 concentration (ci) rose, i.e. the decrease in A of the cooled plants was the result of non-stomatal factors. Changes in dark respiration did not account for the decline in A.Clear evidence was obtained of sink control of A by independently manipulating the temperature of different leaves on the plant. Cooling (to 19°C) most of the plant (the sink) led to a 70% decline in A of the remaining leaves at 30°C after 3 d, whereas the converse treatments (30°C sink, 19°C source) resulted in small changes (17%). In plants at 19°C which were exposed to low CO2 concentration to prevent photosynthesis, A was not reduced when measured at normal CO2 concentrations, indicating that carbohydrate accumulation was responsible for the decline in A. Dry-matter build-up at suboptimal temperature was also consistent with end-product inhibition of photosynthesis.

Quantitative genetic variation and natural selection in Cleome serrulata growing along a mild soil moisture gradient

The purpose of this study was to determine the potential for evolutionary change for several growth characters in a natural population of the annual plant Cleome serrulata Pursh by measuring directional selection pressures and quantitative genetic variation. The population grew along a mild soil moisture gradient, which allowed changes in selection pressures along the environmental gradient to be assessed. Directional selection pressures were calculated for initial height, height growth rate, initial leaf number, and leaf production rate for the wet and dry halves of the population separately. Narrow-sense heritabilities and genetic correlation estimates for these four variables, along with seed mass and emergence time, were estimated in the greenhouse from the offspring of controlled crosses. Selection pressures varied among phenotypic characters for different fitness components and subpopulations. Viability selection on the four characters was similar in the wet and dry subpopulations, with faster height growth rates being favored. Fecundity selection on all four characters was quite different in the wet and dry subpopulations. Overall, there was significant net positive selection on height characters in the dry subpopulation and on leaf number characters in the wet subpopulation. Height characters had lower heritabilities than leaf number characters but showed stronger maternal effects. Initial size measures showed negative genetic correlations with growth rates. The results suggested that these morphological characters had a greater impact on fitness in wetter areas, while physiological characters were more important in the drier areas.

Genetic variation in aspects of leaf growth of Populusclones, using the leaf plastochron index

Leaf growth characteristics of seven clones of Populustrichocarpa, P. nigra, and interspecific hybrids with P. deltoides were examined on 1-year-old cuttings grown in a controlled-environment growth chamber. The plastochron index, a morphological time scale that is a linear function of time and correlated with other morphogenetic and physiological developmental processes, was applied to this development and growth study. Uniformity of leaf initiation was studied; new leaves were initiated at regular time intervals, at least under the controlled conditions of this study. Clones with a high leaf production rate (e.g., P. nigra clone Italica) had a low leaf growth rate and leaves reached maturity at a high leaf plastochron index (LPI 11). Fast-growing and high-yielding P. trichocarpa × P. deltoides hybrids showed the highest leaf growth rates and had a similar leaf production rate to P. trichocarpa. Despite considerable differences in leaf production rates, leaf maturity, and absolute leaf growth rates, only small differences in relative leaf growth rate were observed among the clones.

EFFECT OF MANIPULATION OF WATER AND NITROGEN SUPPLIES ON THE QUANTITATIVE PHENOLOGY OF LARREA TRIDENTATA (CREOSOTE BUSH) IN THE SONORAN DESERT OF CALIFORNIA

Two years of water and nitrogen augmentation experiments on Larrea tridentata (creosote bush) were carried out in a southern Californian warm desert wash plant community. Treatments consisted of control (C), water (W), water and soil nitrogen (W + SN), and soil nitrogen (SN). Quantitative phenological data and microclimatic measurements were collected prior to the onset of and during the growth period and treatments. Predawn and midday water potentials were lower in nonirrigated than irrigated individuals. Leaf conductance was higher in irrigated than in nonirrigated shrubs, with a maximum difference of 1 cm s‐1 observed in July 1984 under relatively low vapor pressure deficit conditions. Leaf production rates were significantly higher in the irrigated (W and W + SN) treatments than in the nonirrigated (C and SN) treatments in 1984. Addition of soil nitrogen caused no increased in vegetative growth rates in 1984. In 1985, a drier year, there was only minimal growth during the spring and summer growth periods in the nonirrigated treatments, while the W and W + SN treatments resulted in significantly higher leafand shoot growth rates. Growth rates in 1985 were significantly higher in the W + SN treatment than in the W treatment. Reproductive growth was higher in the nonirrigated than the irrigated treatments, with the lowest reproductive activity noted in the W treatment.

Litterfall and productivity in a tropical rain forest, Southern Baakundu Forest Reserve, Cameroon

ABSTRACTLitterfall was measured monthly in ten 1 m2 traps in each of two 0.25 ha plots in the rain forest of Southern Bakundu Forest Reserve, Cameroon for 18 months from 1 July 1982 to 31 December 1983. Particular emphasis was placed on measuring species contributions and in relating litterfall to climatic factors; the litterfall data were also used in estimating leaf production. Annual litterfall ranged between 12.9 and 14.1 t ha−1 and was partitioned to leaves (61–66%), branches (23–38%), fruits and flowers (8–12%) and ephiphytes (0.8%). Emergents and top canopy species like Desbordesia glaucescens (evergreen) and Ceiba pentandra (deciduous) contributed more litter than the numerically dominant lower storey species like Cola lepidota and Diospyros spp. Litter fell throughout the year but was greatest during the dry season (November to March); litterfall was thus strongly negatively correlated with environmental moisture variables and could be predicted from its linear regression on time of year, throughfall and relative humidity. By correcting the leaf fall data for leaf weight losses due to grazing and re-translocation, leaf production rates of 10.2 to 11.2 t ha−1 yr−1 were estimated for the forest.

Genotypic Differences in the Temperature Responses of Tropical Crops

In greenhouse trials, seedling emergence and leaf growth of 5 pearl millet [P. americanum] and 7 groundnut cultivars were measured at soil temp. of 7-27°C. Rate of seedling emergence varied greatly between pearl millet cultivars, but was very similar in all groundnut cultivars. In pearl millet there were strong correlations between germination rate and leaf production rate, hourly leaf extension and seedling emergence. The thermal time requirements of various processes are discussed

Growth and Yield of Barley Isopopulations Differing in Solute Potential1

The active accumulation of solutes by osmotically stressed plants is thought to be an adaptive response that increases the ability of drought‐ or salt‐stressed plants to maintain leaf water content, turgor, and possibly growth. In an earlier study we developed two barley (Hordeum vulgare L.) isopopulations differing in solute potential (ψs), and these isopopulations were characterized for their response to salt stress in the growth chamber. At each stress level tested, the low‐ψs population had about 0.1 MPa lower ψs. In the present study we used these isopopulations to test the effect of genetic differences in ψs on growth in well‐watered and drought‐stressed conditions in the greenhouse and field. When grown in the greenhouse, the low ψs population had a slower rate of leaf production and accumulated significantly less total aboveground dry matter by midanthesis than did the high‐ψs population. This difference (up to 35%) was greatest in optimal environmental conditions (adequate water, high irradiance, warm temperatures) and decreased in less favorable environments. The growth differences were not associated with differences in partitioning of dry matter to the leaves or differences in water use efficiency. The growth disadvantage of the low‐ψs population was also observed for grain yield (11–44%) and total aboveground biomass production (10–25%) under dryland and irrigated conditions in multisite field trials. Thus the development of a barley isopopulation with constitutively lower ψs resulted in a reduction in yield potential.

Leaf production, growth rate, and age of the palm Prestoea montana in the Luquillo Experimental Forest, Puerto Rico

ABSTRACTLong-term growth rates of 32 palms (Prestoea montana) were studied using height and diameter measurements taken four times between 1946 and 1982. All leaf scars were counted to estimate leaf production rate, and the distance between scars was measured to establish relationships between leaf production and height growth. Height and diameter growth and leaf production of these palms were not constant during this 36-year period. A greater distance between leaf scars was indicative of rapid height growth but not of high leaf production rate. Dominant palms always grew fast (&gt; 20 cm/yr) in height when they were small, but height growth slowed down when they reached the canopy. Small palms with slow height growth remained suppressed and lost the capacity to grow rapidly in height as adults. Diameter growth decreased with age from 0.07 cm/yr (SE = 0.02) between 1946–51 to 0.01 cm/yr (SE = 0.003) between 1951–82. Annual leaf production averaged 4 leaves/yr over the 36 years of study, was significantly different (P = 0.001) between 1946–51 (5.6 leaves/yr) and 1951–82 (3.8 leaves/yr), and was 4.6 leaves/yr for palms that grew &gt;5 m since 1946 and 3.7 leaves/yr for those that remained suppressed. The best estimate for the mean age of all palms was 61.1 yr (SE = 2.4), obtained from long-term population leaf production rates.

Demography, Dispersal and Production of Pandanus tectorius (Pandanaceae) in Fiji

Populations of Pandanus tectorius (Pandanaceae) were examined at coastal and peat swamp sites in Viti Levu, Fiji. Rates of leaf production (10-90 year-1), stem and branch growth (2-80 cm year-1)) were determined and used in conjunction with observations of the number and spacing of leaf scars and peduncle scars to estimate plant age. A semiprostrate juvenile phase of 4.5-9 years is followed by erect trunk growth for c. 5-12 years followed by a flowering phase lasting 40 years or more. Male plants form about 30 branches and flower annually, while female plants form about 16 branches and flower biennially. Each fruit forms about 76 phalanges (drupes) and each phalange contains up to eight embryos, although many were parasitised by insect larvae. Dispersal of phalanges by Pteropus tonganus (Chiroptera), water, man and crabs or rats was recorded. In swamp sites occasional fires kill many of the small-medium-sized plants, while cyclones damage and kill large plants at all sites. Because infrequent but severe destructive events limit survivorship, it is difficult to define characteristic natalities or mortalities. The sex ratio of the population indicates a slight preponderance of females. The allocation of biomass to reproduction is estimated to be c. 34% in females and 15% in males, at 60 years.

Demography of Cyathea hornei (Cyatheaceae), a Tropical Tree-Fern in Fiji

A population of the tree-fern Cyathea hornei (Cyatheaceae) was studied in the tropical forest environ- ment of Viti Levu, Fiji. Plants monitored over a 2.5 year period indicated that leaf production is greatest in the hot, wet season and that leaf longevity is 1.1-1.6 years. Plants vary in the rates of leaf production (3-9 year-1) and stem growth (1.5-40 cm year-1). From the spacing of leaf scars on the stems and observed growth rates it is possible to estimate the growth history and age of plants. The age class structure of the populations is consistent with a 2% annual mortality, and the largest plants observed (550 cm stem length) have an age of 80-105 years. Reproduction commences in plants of about 150 cm stem length, and each fertile plant produces 4 x 107 2 2 x 107 s.d. spores year --1. Annual net production varies greatly, up to 760 g year--1, and in typical fertile plants is allocated as follows: roots 15%; stems 23%; leaves 58%; and sori 4%.

Light Variation and Carbon Gain in Rain Forest Understorey Palms

(1) The consequences of light variation for daily carbon gain in three understorey palm species are described. Detailed measurements of photosynthetic photon flux density (PPFD) were made in closed-canopy understorey, gap-edge and gap-centre sites to determine the range of light conditions. Based on these results and the responses of seedlings grown in full shade, computer simulations were used to compute total daily leaf carbon gain. (2) Median daily total PPFD in gap-edge habitats was 1-1.5 mol m-2, compared with 0.26-0-33 mol m-2 in adjacent understorey sites. Median daily PPFD in the gap centre increased with gap size. In the understorey, more than 80% of averages calculated for 5-min periods were below 10 ,umol m-2 S-1, whereas most readings in the centre of a 150-M2 gap were between 50-100 ,umol m-2 s-1 and along the gap edge 20-50 ,umol m-2 s(3) For Asterogyne martiana and Geonoma cuneata, two dwarf species, median daily total PPFD did not increase from ground level to 1-5 m. Fifty per cent of all PPFD measurements below 1-5 m were between 0 -18-0-39 mol m-2. At crown heights above 1.5 m, median daily total PPFD increased to 0.51 mol m-2. Within clones of G. congesta, daily total PPFD increased significantly with crown height; median PPFD incident on crowns 3-5-4-0 m tall was five times greater than PPFD at heights below 1.4 m. (4) On sunny days, the proportion of daily total PPFD contributed by sunflecks ranged from 10% to 78%. The relative proportion of daily PPFD contributed by sunflecks increased as the PPFD of background diffuse radiation decreased. (5) Photosynthesis of seedlings grown in full shade did not differ significantly among the three species. Light compensation points of full-shade-grown plants were between 3-4 ,umol m-2 s-1, and light-saturated photosynthetic rates measured as CO2 uptake were between 3 and 4 ,umol m-2 s-1. Light saturation occurred between 200 and 400,umol m-2 s(6) Carbon gain simulations of full-shade-grown seedlings indicate that a positive carbon gain over 24 h occurs at PPFD greater than 0.20 mol m-2. When most of the total daily PPFD was in the form of diffuse radiation, total daily carbon gain was linearly related to total daily PPFD. Daily carbon gain was not a simple function of daily total PPFD when sunflecks contributed more than 50% of the total quantum flux. On days with sunny periods, the proportion of total daily carbon gain during sunflecks ranged from 15% to 60%. (7) Seedlings of the three species grown in the gap edge had higher rates of leaf production, were taller and had larger leaves than seedlings grown in a closed-canopy understorey site. Measurements of growth and photosynthesis, and carbon-gain simulations suggest that light conditions along gap edges and within small gaps are ideal for these species.

EFFECT OF AGING ON GROWTH AND FLOWERING OF THE TERMINAL BUD OF PHARBITIS NIL

The tendency of the terminal bud of Pharbitis nil to flower after one long night was studied in the context of growth changes occurring with aging. Seedlings were grown under constant light and temperature, selected for uniformity and subjected to a 16‐hr dark period at ages ranging from 3 to 14 days. A decline in percent terminals flowering was observed after day 6, to zero at day 10. Flowering of the terminal was obtained in some plants, thereafter. Floral index of development scored lower for terminals flowering on days 7–9 and 11–14 than on days 3–6. Loss of the tendency to flower was associated with a decline in rate of leaf production in the terminal bud and a change in rate of elongation of the epicotyl axis. The data lend support to a nutrient‐diversion hypothesis in the control of flowering in Pharbitis.

Effect of Aging on Growth and Flowering of the Terminal Bud of Pharbitis nil

The tendency of the terminal bud of Pharbitis nil to flower after one long night was studied in the context of growth changes occurring with aging. Seedlings were grown under constant light and temperature, selected for uniformity and subjected to a 16-hr dark period at ages ranging from 3 to 14 days. A decline in percent terminals flowering was observed after day 6, to zero at day 10. Flowering of the terminal was obtained in some plants, thereafter. Floral index of development scored lower for terminals flowering on days 7–9 and 11–14 than on days 3–6. Loss of the tendency to flower was associated with a decline in rate of leaf production in the terminal bud and a change in rate of elongation of the epicotyl axis. The data lend support to a nutrient-diversion hypothesis in the control of flowering in Pharbitis.

Leaf dynamics and profitability in wild strawberries.

Leaf dynamics and carbon gain were evaluated for two species of wild strawberry, Fragaria virginiana and F. vesca. Five populations on sites representing a gradient of successional regrowth near Ithaca, N.Y., U.S.A., were studied for two or three years each. A computer-based model of plant growth and CO2 exchange combined field studies of leaf biomass dynamics with previously-determined gas exchange rates to estimate carbon balances of leaves and whole plants in different environments.Leaves were produced throughout the growing season, although there was usually a decline in rate of leaf-production in mid-summer. Leaves produced in late spring had the largest area and longest lifespan (except for overwintering leaves produced in the fall). Specific Leaf Weight (SLW) varied little with time of leaf production, but differed greatly among populations; SLW increased with amount of light received in each habitat. The population in the most open habitat had the least seasonal variation in all leaf characters. F. vesca produced lighter, longer-lived leaves than F. virginiana.Simulations showed that age had the largest effect on leaf carbon gain in high-light environments; water stress and temperature had lesser effects. Leaf carbon gain in lowlight environments was relatively unaffected by age and environmental factors other than light. Leaves in high-light environments had the greatest lifetime profit and the greatest ratio of profit to cost. Increasing lifespan by 1/3 increased profit by 80% in low-light leaves and 50% in high-light leaves. Increasing the number of days during which the leaf had the potential to exhibit high photosynthetic rate in response to high light led to little change in profit of low-light leaves while increasing profit of high-light leaves by 49%.

Influence of Tillage on Phenology and Carbohydrate Metabolism of Spring Wheat1

AbstractNo‐tillage systems help reduce soil erosion, yet crop growth is often adversely affected by the presence of surface residue. The specific effects of no‐tillage systems on phenological events of spring wheat (Triticum aestivumL.) have been poorly characterized. A field study was conducted on a Palouse silt loam (fine‐silty, mixed, mesic Pachic Ultic Haploxeroll) during 1983 and 1984 to examine the growth and development of four spring wheat cultivars grown under conventional (fall plow and spring disk) and no‐tillage (direct drilling) tillage systems. Throughout the two growing seasons, leaf and tiller production, tiller abortion, and soil moisture were monitored while leaf area, leaf weight, and stem weight were determined at weekly intervals in 1983. The length of the second leaf on the main stem, rate of leaf production, and rate of tiller production were reduced in plants grown in no‐tillage compared with conventional tillage. Except for the cultivar ‘Waverly’, tiller production was reduced by no‐tillage but tiller abortion was not. More soil water was available throughout the season in the no‐tillage plots, yet the plants grown in no‐tillage tended to be smaller than conventionally grown plants. Total nonstructural carbohydrates in the lower stem‐crown area at 12 days after anthesis were not affected by tillage treatment, and all cultivars had used most of this stored carbohydrate by physiological maturity. Overall, these results indicated that stresses that occur early in seedling development under no‐tillage reduced early growth and the plants were unable to overcome these effects prior to maturity. However, cultivars differed in tolerance to these early stresses. Thus, it should be possible to develop spring wheat cultivars for growth under no‐tillage.

Early growth of Potamogeton pectinatus L. in response to temperature and irradiance: Morphology and pigment composition

When recently germinated Potamogeton pectinatus L. tubers were grown at temperatures ranging from 10 to 37°C under low irradiances (6–120 μE m −1 s −1), temperature exerted a stronger influence on levels of the pigments chlorophyll a and chlorophyll b than did irradiance. Temperature and irradiance interacted to influence the level of total carotenoids. At low irradiances, changes in temperature modified the concentrations of accessory pigments relative to chlorophyll a. Two indicators of growth were also strongly affected by temperature. The relative rate of shoot elongation varied from −0.04 to 1.23 mm cm −1 day −1. At 23–30°C, the relative shoot elongation rate was inversely related to irradiance, but at temperatures outside this range irradiance had no influence on the relative shoot elongation rate. The relative leaf production rate varied from 0 to 0.28 leaves leaf −1 day −1 and increased with temperature and irradiance. No leaves were produced at 37°C. These results indicate that the optimum temperature for early growth of P. pectinatus is near 23–30°C, and that, during the early growth period, temperature may be as important as irradiance in influencing growth of P. pectinatus.