Single Leaf Area Research Articles

Canopy probabilistic reconstruction inferred from Monte Carlo point-intercept leaf sampling

The usefulness of a probabilistic technique to describe 3D foliage geometrical traits depends on the possibility of quickly and cheaply collecting a leaf data sample. The present simulation study was designed to provide the statistical information necessary to drive and control a foliage random sampling process on a real tree canopy (considered as a population of leaves) and to evaluate two corresponding statistical reconstruction outputs. A point-intercept leaf collection method was simulated on a single walnut-tree crown (7.20 m 2 surface area) by performing a Monte Carlo (MC) sampling from a data set obtained by digitising all 1558 leaves. Random (R) and adaptive Kernel (aK) methods were employed for foliage synthesis. Thirty canopies reconstructed from the same MC data sample (describing 250 leaves, i.e. less than 20% of crown leaf number) by both procedures indicated that the variability associated with each simulation process can be neglected, i.e. MC leaf sampling played the principle role in driving foliage reconstruction and deciding canopy geometrical traits. A crucial point of the procedure was to define a method to construct confidence envelopes for the artificial geometrical canopy parameters, given that for practical concerns in the field there is a need to sample the real canopy only once: 30 independent samples (describing 250–300 leaves) were generated by resampling with replacement (bootstrapping) one extracted leaf data sample (describing 300 leaves) and the corresponding canopies were simulated. The reconstructed canopies were characterised from a structural perspective in terms of foliage surface area, vertical leaf area density, single leaf area, and leaf angles. The synthesised canopies were evaluated from a functional perspective in terms of sunlit surface area projected orthogonal to sunbeam direction (silhouettes), and sky vault-integrated silhouette to (canopy) area ratio (STAR SKY). The virtual walnut-tree foliage reproduced by electromagnetic digitising was the reference to corroborate all corresponding reconstructed canopies. The aK method appeared more accurate and precise than the corresponding R technique to represent real foliage geometrical traits. In general, the proposed aK statistical canopy reconstruction method appears to be promising to infer the geometrical features of a broad-leaf tree crown from a foliage sub-set, even if its applicability depends on the size of the considered tree, i.e. on the practicability of collecting a leaf data sample.

The Responses of Momordica Charantia at Different Modular Levels to the Changes of Support Diameter

The morphological plasticity of plants occurs due to the changes of modular quantity dynamics, modular patterns and modular morphologies. Climbing plants differ from non_climbing and self_supporting plants in many growth characteristics, which mainly result from biomechanical constraints. The morphology and growth of climbing plants may be affected by external supports to a large extent. External supports are important resources and determine the strategies which climbing plants use to obtain maximum sunlight. The object of this study is to describe the effects of external support diameter on growth, biomass allocation and morphological plasticity of herbaceous climbing plants at different modular levels. Three questions are addressed in this study: 1) Do plants have growth, biomass allocation and morphological plasticity responses at different modular levels on different external support diameters? 2) If so, what is the difference between the various modular levels? 3) What is the meaning of those responses on climbing plants to search and locate the external support? The garden experiment was carried out in the Ecological Garden of Southwest China Normal University with a perennial herbaceous climbing species- Momordica charantia. On 6 May 2000, the seedlings of M. charantia with the same size were planted in 40 figuline containers filled with cultivated soil, one seedling per pot. External supports were made of iron line covered with PVC at the beginning of the experiment. All plants were divided into four groups, and each group had supports with 2 mm, 4 mm, 8 mm, 12 mm and 16 mm in diameter, respectively. Each plant was supplied with the same quantity of water and nutrient during the experiment. From 7 June to 6 July, the individual's growth conditions and branch numbers were recorded at 10 day intervals. All individuals were harvested at 25 August and divided into main stem and shoot, the following parameters were measured separately: a) internode length, b) internode diameter, c) petiole length, d) single leaf area, e) the number of primary branch and f) second branch and the distance from primary branch to base of main stem. The individuals were separated into root, main stem, shoot, lamina, petiole, flower and fruit, and cleaned by tap water and oven_dried for 72 h at 84 ℃, then weighed separately. The main results of this study were as follows: 1) The climbing efficiency of plants was significantly affected by support diameters with climbing efficiency reducing with increase in support diameter. The climbing growth rate of plants on the 2 mm, 4 mm, 8 mm, 12 mm and 16 mm supports were 3.00, 3.00, 2.13, 0.88 and 0.75, respectively; 2) The changes of support diameters did not affect the timing of shoot occurring but significantly affected the shoot numbers and shoot sites along stem. The first primary shoot of all individuals sprouted between 13 June and 17 June, the means of primary shoot numbers on the 2 mm, 4 mm, 8 mm, 12 mm and 16 mm supports were 12.3,10.0,11.3,14.3 and 14.6, respectively; 3) The individuals had higher sensitivity to the changes of support diameter than those of shoots. Plants showed powerful capacity of searching external supports when they encountered the large diameter supports. In this case, the stem extension slowed, specific stem length enlarged, shoot number and branching ratio increased, shoot length and petiole length prolonged, while R/S ratio decreased. The biomass accumulation of individuals was affected slightly by different support diameters, the biomass of individuals grown on the 2 mm, 4 mm, 8 mm, 12 mm and 16 mm supports were 43.56 g, 47.29 g, 34.32 g, 50.46 g and 31.44 g, respectively; 4) The changes of external support diameters had no significant effect on morphological characteristics and biomass characteristics of shoots; 5) The changes of morphology, biomass allocation and shoot behavior of individuals were the responses of the climbing plants to the availability of external supports, which would help the individuals to enhance the capacity of foraging support

Effects of Elevated CO2 Concentration on Phenotypic, Physiological and Biochemical Characteristics of Submersed Plant Potamogeton crispus Leaf

The effects of elevated CO 2 concentration on growth and development of terrestrial plants have been studied intensively, but less scientific interest h as been raised on aquatic plants. In this study, a greenhouse experiment with su bmersed species Potamogeton crispus, one of dominant species in lakes along Yangtze River Basin, was studied comparatively in higher (1 000±50 μmol·mo l -1 ) and ambient (about 380 μmol·mol -1 ) CO 2 concentration to t e st whether CO 2 has significant impacts on phenotypic and some physiological an d biochemical characteristics as main effect. In addition, allometric analysis w as applied to distinguish whether phenotypic changes such as total leaf area are induced by environment (plastic) or plant size dependent (non_plastic). The res ults showed that phenotypic characteristics of P. crispus leaf in elevated C O 2 concentration changed significantly compared with that in ambient CO 2 concent ration. Leaf shape was more stubby, but leaf width, single leaf area, total leaf area per plant and leaf area ratio increased significantly in elevated CO 2 co ncentr ation. However, specific leaf area and leaf length did not differ between treatm ents. Total leaf area per plant was closely correlated with plant weight, indica ting that change in this phenotypic characteristic may depend on plant size. The result of allometric analysis certified that this change was a non_plastic resp onse, but plant size dependent. In addition, higher CO 2 concentration led to t he changes in pigment concentration. Chlorophyl a, chlorophyl b, total chlorophyl, carotenoid concentration and the ratio of chlorophyl a/b decreased in elevated CO 2 concentration. The soluble sugar concentration increased, but protein, N a nd P content decreased under higher CO 2 condition. It is concluded that elevated a tmospheric CO 2 concentration results in significant changes in some physiologi ca l and biochemical characteristics, especially increase of soluble sugar concentr ation, but not necessary in leaf phenotype. Maybe true adjustment in leaf ph enotype is under strong genetic rather than CO 2 control.

An inducible activator produced by a Serratia proteamaculans strain and its soybean growth-promoting activity under greenhouse conditions

Serratia proteamaculans 1-102 (1-102) promotes soybean-bradyrhizobia nodulation and growth, but the mechanism is unknown. After adding isoflavonoid inducers to 1-102 culture, an active peak with a retention time of about 105 min in the HPLC fractionation was isolated using a bioassay based on the stimulation of soybean seed germination. The plant growth-promoting activity of this material was compared with 1-102 culture (cells) and supernatant under greenhouse conditions. The activator was applied to roots in 83, 830 and 8300 HPLC microvolts (microV) per seedling when plants were inoculated with bradyrhizobia or sprayed onto the leaves in same concentrations at 20 d after inoculation. The root-applied activator, especially at 1 ml of 830 microV per seedling, enhanced soybean nodulation and growth at the same level as 1-102 culture under both optimal and sub-optimal root zone temperatures. Thus, this activator stimulating soybean seed germination is also responsible for the plant growth-promoting activity of 1-102 culture. However, when sprayed onto the leaves, the activator did not increase growth and in higher concentrations decreased average single leaf area. The results suggest that this inducible activator might be a lipo-chitooligosaccharide (LCO) analogue. LCOs act as rhizobia-to-legume signals stimulating root nodule formation. The activator could provide additional 'signal', increasing in the signal quality (the signal-to-noise ratio, SNR) of the plant-rhizobia signal exchange process.

An inducible activator produced by a Serratia proteamaculans strain and its soybean growth‐promoting activity under greenhouse conditions

Serratia proteamaculans 1‐102 (1‐102) promotes soybean–bradyrhizobia nodulation and growth, but the mechanism is unknown. After adding isoflavonoid inducers to 1‐102 culture, an active peak with a retention time of about 105 min in the HPLC fractionation was isolated using a bioassay based on the stimulation of soybean seed germination. The plant growth‐promoting activity of this material was compared with 1‐102 culture (cells) and supernatant under greenhouse conditions. The activator was applied to roots in 83, 830 and 8300 HPLC microvolts (μV) per seedling when plants were inoculated with bradyrhizobia or sprayed onto the leaves in same concentrations at 20 d after inoculation. The root‐applied activator, especially at 1 ml of 830 μV per seedling, enhanced soybean nodulation and growth at the same level as 1‐102 culture under both optimal and sub‐optimal root zone temperatures. Thus, this activator stimulating soybean seed germination is also responsible for the plant growth‐promoting activity of 1‐102 culture. However, when sprayed onto the leaves, the activator did not increase growth and in higher concentrations decreased average single leaf area. The results suggest that this inducible activator might be a lipo‐chitooligosaccharide (LCO) analogue. LCOs act as rhizobia‐to‐legume signals stimulating root nodule formation. The activator could provide additional ‘signal’, increasing in the signal quality (the signal‐to‐noise ratio, SNR) of the plant–rhizobia signal exchange process.

Modelling compensatory effects of defoliation on leaf area growth and biomass of sunflower ( Helianthus annuus L.)

Leaf area loss is a typical damage of fungal and insect attacks or hail. In this work growth responses to defoliation were analysed by removing 50% of leaf area at different phenological stages in sunflower ( Helianthus annuus L.). Plants defoliated at head-visible stage showed an increased single leaf area which partly compensated the reduction in light interception during the season, while later treatments, during pre-anthesis and complete anthesis, did not show increased single leaf area but a delayed leaf senescence. A decrease in biomass accumulation was observed particularly in pre-anthesis treated plants. Results were implemented into the crop model OILCROP-SUN 6.0 to assess the impact of compensation on growth and yield. It was concluded that leaf area recovery should be incorporated into the growth models for a reliable simulation of yield after partial defoliation.

Estimation of Leaf Area in Tropical Maize

Leaf area development at regular time intervals during the growing season is estimated by many crop growth models and is needed for competition studies. In plant breeding programs, observation is generally restricted to a single leaf area estimate or assessment of the plant type. Two procedures that build on earlier studies are presented to estimate total plant leaf area of maize (Zea mays L.). Leaf area development of six tropical maize cultivars grown in 1995 and 1996 in several tropical environments in Mexico (both favorable and moisture‐ and N‐limited) was observed and analyzed. First, the validity of a bell‐shaped curve describing the area of individual leaves as a function of leaf number was investigated. When individual cultivar–environment combinations were normalized for area of the largest leaf and for total leaf number, one parameter set described all combinations. It remained difficult, however, to estimate these parameters in advance, which limits predictive applications in crop growth models. Analytical application after flowering, when parameter values can be determined, is possible. Second, a method was developed to directly estimate total leaf area when total leaf number and area of the largest leaf are known. The method makes use of the facts that the area of the largest leaf relative to total plant leaf area is constant and that this constant is linearly related to total leaf number. This study has shown that approaches previously presented by others are applicable in modified form over a wide range of environmental conditions.

An analysis of the growth of leaf area of oil palms in Indonesia

In two cultivar × density trials for oil palms (Elaeis guineensis) planted in Indonesia, single leaf area, number of green leaves per tree, leaf opening rate per year and rachis length of leaves were followed over fourteen years. The data were analysed to determine the time course of canopy leaf area and to predict the moment of canopy closure.Growth functions were fitted to the observed data. Estimates of leaf area index (L) were based on single leaf area, number of green leaves, leaf opening and planting density. The time course of L was modelled on the basis of the fitted functions to the components. The moment of canopy closure was calculated from the planting density and the functions fitted for rachis length.The modelled time course of L was considerably different from the function fitted to the single leaf area data. The expansion of L was not as rapid as expected from the area growth of single leaves and, after maximum L was reached, a steady decline was observed. The continuously declining number of green leaves was the main cause of these two observations.The time course of L differed considerably between the two experiments. Not only were there large differences in the number of green leaves maintained per tree in the experiments but also the final area of single leaves differed between both experiments. The first factor was a result of the management of the experiments, whereas the second factor was most likely influenced by a difference in soil-related factors at the two locations.Leaf areas and numbers of leaves per tree were different for each cultivar, as was L. This was also the parameter most sensitive to planting density. Individual leaf area and leaf number per tree were not affected by planting density, but rachis length was affected by the planting density treatment. The moment of canopy closure was similar in both experiments. Planting density was the main factor that determined the onset of canopy closure.

Evaluation of Discriminant Analysis in Identification of Low‐ and High‐Water Use Kentucky Bluegrass Cultivars

Identification of water conserving Kentucky bluegrass (Poa pratensis L., KBG) is an important objective in turfgrass breeding programs. Warm‐season turfgrass selections with low evapotranspiration (ET) rates have been successfully identified by components of canopy resistance to ET and leaf area. The objective of this study was to determine the effectiveness of discriminant analysis in distinguishing water conserving KBG on the basis of canopy resistance and leaf area from a population of 61 KBG cultivars. By means of cluster analysis, the 61 KBG cultivars were categorized as either low‐ or high‐water use cases based on ET rate evaluated in the growth chamber at three VPD environments (1.263,1.664, and 2.261 kPa). Fourteen morphological and growth characteristics were assessed in the greenhouse with unmowed, spaced plants and mowed turfgrass (20‐cm‐diam. lysimeters). Based on single plant morphology, five‐ and seven‐variable discriminant functions were identified that correctly classified cases into their actual water use groups with an estimated 70.5% actual error rate from cross‐validation with the leave‐one‐out method (LOER). Compared with single plant morphology, turfgrass morphology was more efficient in requiring fewer predictors (hence fewer measurements) to perform classification. Based on turfgrass morphology, two and three‐variable functions were identified that correctly classified an estimated 75.4% of the cases into their true water use groups. A 75.4% correct classification was the best achieved and was as good as that obtained with all 14 original variables in the analysis simultaneously. Leaf angle, a component of canopy resistance, was the most important discriminator of water use group, predicting actual group membership in 72.1% of the cases. Correct classification was improved only slightly over leaf angle alone by incorporating a single leaf area component such as leaf width or leaf extension rate. These results show that discriminant analysis may be an efficient and useful tool for predicting the water use patterns of new cultivars on the basis of a few plant measurements that are routinely assessed by breeders.

Photosynthetic and growth responses of old and modern spring wheat cultivars to atmospheric CO 2 enrichment

Cultivars of spring wheat ( Triticum aestivum L.) introduced between 1890 and 1988 were cultivated in pots under optimal growth conditions and exposed during the whole growing season to normal (379 p.p.m.) and elevated CO 2 concentrations (689 p.p.m.) in open-top chambers. CO 2 effects were measured at anthesis on flag leaf composition (chlorophyll and protein) and photosynthetic parameters, and at maturity on plant growth and yield. CO 2 enrichment did not affect light saturated rate of photosynthesis measured at 400 p.p.m. CO 2 or protein, total chlorophyll and dry weight content per unit leaf area. However, single flag leaf area and fresh weight per leaf area were increased by CO 2. This increase was possibly responsible for a significant decrease in the chlorophyll a/b ratio. Under normal atmospheric CO 2 concentration, the total above-ground biomass, stem weight and height, and ear number were negatively correlated with the year of cultivar release. Despite no evidence of CO 2 acclimation, i.e. changes in flag leaf composition, CO 2 enrichment resulted in a greater growth stimulation of the older than the modern cultivars. This was due to a greater CO 2 effect on those growth components that were altered during plant breeding of wheat in the past, i.e. stem weight and height, and ear number. The average CO 2-related increase in biomass and grain yield amounted to ca 46% and 28% for the three old (1890–1943) and three modern cultivars (1965–1988), respectively. Differences in yield response to CO 2 enrichment between old and modern cultivars could be mainly explained by changes in ear number.

Molecular genetics of growth and Development in Populus (Salicaceae). V. Mapping quantitative trait loci affecting leaf variation

We examined the genetic variation of leaf morphology and development in the 2-yr-old replicated plantation of an interspecific hybrid pedigree of Populus trichocarpa T. & G. and P. deltoides Marsh. via both molecular and quantitative genetic methods. Leaf traits chosen were those that show pronounced differences between the original parents, including leaf size, shape, orientation, color, structure, petiole size, and petiole cross section. Leaves were sampled from the current terminal, proleptic, and sylleptic branches. In the F2 generation, leaf traits were all significantly different among genotypes, but with significant effects due to genotype X crown-position interaction. Variation in leaf pigmentation, petiole length. And petiole length proportion appeared to be under the control of few quantitative trait loci (QTLs). More QTLs were associated with single leaf area, leaf shape, lamina angle, abaxial color, and petiole flatness, and in these traits the number of QTLs varied among crown positions. In general, the estimates of QTL numbers from Wright's biometric method were close to those derived from molecular markers. For those traits with few underlying QTLs, a single marker interval could explain from 30 to 60% of the observed phenotypic variance. For multigenic traits, certain markers contributed more substantially to the observed variation than others. Genetic cluster analysis showed developmentally related traits to be more strongly associated with each other than with unrelated traits. This finding was also supported by the QTL mapping. For example, the same chromosomal segment of linkage group L seemed to account for 20% of the phenotypic variation of all dimension-related traits, leaf size, petiole length. and midrib angle. In both traits. the P. deltoides alleles had positive effects and were dominant to the P. trichocarpa alleles. Similar relationships were also found for lamina angle. abaxial greenness, and petiole.

The effects of ozone and nutrient supply on stomatal response in birch (Betula pendula) leaves as determined by digital image‐analysis and X‐ray microanalysis

Cuttings of Betula pendula Roth were grown in field fumigation chambers throughout one growing season in filtered air with < 3 nl l-1 O3 (control; C) or day/night = 90/40 nl 1-1 O3 (ozone fumigation: O3 ). Plants were watered with either low (0·005 %: LF) or high-concentrated (0·05%: HF) fertilizer solution. Discs between second-order veins in the central portion of the leaves were excised and immediately cryofixed in liquid nitrogen for low-temperature scanning electron-microscopy (LTSEM) at 1000 hours and 1400 hours. Stomatal width, area and density were measured by digital image-analysis. X-ray counts of potassium (K) and calcium (Ca) ions were determined by means of energy-dispersive X-ray microanalysis in guard and subsidiary cells. Accurate and fast measurements of stomatal apertures by image analysis were possible in birch leaves, because the darkness of the stomatal pore contrasts with the brightness of the guard cells and the cuticular ledges. Regression analysis showed a close relationship between the stomatal width and the pore area (r= 0·938, P < 0·01). At all harvest times, the stomatal pores were significantly narrowed in the high fertilization control treatment (O3 /HF vs. O3 /LF), and in the ozone treatment at 1400 hours (O3 /HF vs. C/LF). In addition to this fertilization effect, ozone had also narrowed the stomatal pores (O3 /HF vs. C/HF at 1400 hours, O3 /LF vs. C/LF at all harvest times). In addition to these functional effects, morphological effects (individual leaf area, stomatal density) were determined. Single-leaf area was increased by high fertilization, with a tendency to decrease with O3 fumigation. The stomatal density in intercostal fields was increased by O3 but decreased by high fertilisation. Stomatal widening was accompanied by increased K count rates in the guard cells, in contrast to constant K values in the subsidiary cells, irrespective of the fumigation or fertilization regimes. Calcium counts in the guard cells were similar to those in the subsidiary cells, and were independent of the aperture width. In samples with established ozone injury, the K/Ca ratio in collapsed guard cells increased compared with turgid guard cells irrespective of the pore aperture. Collapsed subsidiary cells only differed from turgid subsidiary cells when the guard cells had also collapsed and thus closed the pore.

White Clover Response to Grazing Method

AbstractGrazing management is a major factor influencing white clover (Trifolium repens L.) growth. Our objective was to determine the response of white clover cultivars differing in leaf size to grazing method (continuous vs. rotational stocking) using cattle (Bos spp.). In each of 2 yr, a predominantly tall fescue (Festuca arundinacea Schreb.) sod on a Savannah fine sandy loam (fine‐loamy siliceous, thermic Typic Fragiudult) was oversown in September with ‘Grasslands Huia’ (medium‐small leaf), ‘Louisiana S‐1’ (medium‐large leaf), and ‘Regal’ (large leaf) white clover. From March to August of the following year, plots of each cultivar were stocked continuously (3‐ to 5‐cm stubble) on rotationally (grazed to 5‐cm stubble every 35 to 38 d). Clover growth was measured prior to rotational grazing and stolon survival was determined in November. When precipitation during the grazing season was 59% above normal, grazing method had no influence on mean single leaf area, stolon dry weight, and stolon growing point density of white clover. In contrast, continuous stocking reduced these responses when precipitation was 32% below normal the following year. Cultivar ranking for mean single leaf area was generally the same as that for leaf size category: Grasslands Huia &lt; Louisiana S‐1 &lt; Regal. Although stolon length and growing point density were frequently greatest for Grasslands Huia, stolon survival of Grasslands Huia was no greater than that of the larger‐leafed cultivars. Despite varying effects of grazing method on growth and morphology, stolon survival of white clover was always greater under rotational stocking.

Coconut milk enhancement of axillary shoot growth in vitro of kiwifruit

Abstract We sought to improve methods for micropropagation of kiwifruit (Actinidia deliciosa var. deliciosa) by enhanced axillary branching. We added 10% coconut milk to the treatment medium before autoclaving. We then measured shoot length, shoot freshweight, petiole length, number of single nodes, leaf area, and basal callus freshweight of shoots from the control and treatment media. The addition of 10% coconut milk significantly increased all six shoot parameters over 74 days of incubation. The number of single nodes produced, shoot length, petiole length, and leaf area were approximately doubled. Statistically significant linear correlations between basal callus freshweight and all shoot parameters measured, except leaf area, were found only in the coconut milk‐supplemented medium. This suggests the basal callus was acting as a pseudoroot.

Soybean cultivar difference in leaf photosynthetic rate and its relation to seed yield.

In a field experiment using 17 soybean cultivars and lines with a diverse variation of seed yield within each maturity group (early, middle and late), the association of apparent photosynthetic rates per leaf area (AP) with seed yields was examined. AP was measured of intact leaves of most actively working at three growth stages :vegetative (VT), pod formation (PF), and seed development (SD). Significant cultivar differences in AP within maturity groups were observed at VT and PF of early maturing, at all the three stages of middle maturing, and at SD of late maturing cultivars, respectively. AP tended to increase with growth stage, being accompanied by a variation of' cultivar ranking. Across cultivars and lines in each group, AP tended to be correlated negatively with single leaf area, and positively with specific leaf weight (SLW) and chlorophyll content at VT, but the tendency became ambiguous at later stages. APs measured at VT and PF did not bear significant correlations with crop growth rates (CGR) or net assimilation rates (NAR) determined between the two stages. Seed yields were positively correlated with APs measured at SD in the late maturing group, but no significant correlations between them were observed at other growth stages, or in the early and middle maturing groups. We presumed that greater sink demand by high-yielding cultivars were responsible for a higher AP, not that a higher AP contributed to an increased seed yield.

Growth response to nitrogen in Japonica and Indica rice varieties. II. Differences in the rate of increase in culm length and leaf area due to nitrogen fertilization.

Field experiments on the growth response to nitrogen were conducted for three years (1983-1985) using 49 rice varieties including japonica, indica and japonica-indica hybrid. Rates of increase in culm length and lower internodes as a result of nitrogen fertilization to japonica, japonica-indica hybrid and semidwarf indica were large, intermediate and small, respectively. The rate of decrease in dry weight of the leaf sheath and culm per unit culm length was larger in japonica than that in japonica-indica hybrid and semidwarf indica. The ratio of leaf area to the spikelet number was obviously smaller in japonica-indica hybrid and semidwarf indica compared to that in japonica. However, the ratio of the rate of increase in leaf area to that in the spikelet number due to nitrogen fertilization was larger in these groups than that in japonica. Furthermore, the rate of increase in single leaf area and specific leaf area of japonica-indica hybrid and semidwarf indica were larger than those of japonica. The obtained results suggested that one of the reasons of higher lodging resistance of japonica-indica hybrid and semidwarf indica was ascribed to a little changes in the culm length due to nitrogen fertilization compared to that of japonica. It was also suggested that these groups had a tendency of over-luxuriant growth due to nitrogen fertilization compared to japonica. This characteristic should be improved for breeding high-yielding varieties by using japonica-indica hybrid or semidwarf indica as genetic resources.

Long-term effects of an increased CO2 concentration on terrestrial plants in model ecosystems. Morphology and reproduction ofTrifolium repens L.and Lolium perenne L.

Mixtures (ratio 1∶1, 45 seeds·dm−2) of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) were enclosed in environmentally controlled acrylic mini-glasshouses and supplied with additional CO2 from September 1981 until September 1982 (547–600 ppm, control: ∼340 ppm CO2). At growth optimum the single leaf area of white clover was 30% greater and the specific leaf weight 19% higher with additional CO2; with the perennial ryegrass it was 18% resp. 29%. The length growth of the white clover petioles was enhanced by the additional CO2: in the beginning 67% longer leafstalks, at growth optimum no effect and at the end of the experiment 100%. At growth optimum the specific petiole weight was approximately 52% higher. When the growing was terminated the blades of perennial ryegrass were 19% longer at high CO2. The average volume of the flowerheads was about 53% greater and the adult ears 13% longer. The number of flowers per flower head and the number of earlets per ear did not increase significantly. On an average the white clover seeds were 28% heavier and the caryopses were 4% lighter.

Leaflet expansion rates for fifteen soybean cultivars

Abstract In determining soybean (Glycine max (L.) Merr.) yield, the rate of leaf area expansion may be more important than the rate of apparent photosynthesis per unit leaf area. Fifteen soybean cultivars from two Maturity Groups were surveyed for the rate at which terminal leaflets of the sixth, eighth, and tenth trifoliate leaf expanded under field conditions. Leaflets lenght (LL) and width (LW) were measured every day from when the leaflets were 10–15 mm long until full expansion, a period of 11 or 12 days. Leaflet lenght expansion (LLE) and leaflet width expansion (LWE) rates were calculated from these data. After full expansion, leaflet area (LA) and specific leaf weight (SLW) were determined. Maturity Group III cultivars differed for: LA, LW, and LWE of the sixth, eighth, and tenth leaves; SLW of the sixth and eighth leaves; LLE of the eighth and tenth leaves; and LL of the tenth leaf. Maturity Group IV cultivars differed for SLW, LA, LL, LW, LLE, and LWE for all three leaves. The tenth leaf of most cultivars was smaller and expanded at a slower rate than the sixth leaf. Highly significant correlations between LA and leaflet expansion rates were found (r = 0.55 to 0.90). For the eighth and tenth leaves of Maturity Group IV, high values for SLW were associated with slow rates of leaflet expansion. Specific leaf weight of Maturity Group III was not correlated with any other leaflet characteristic. Because single leaflet expansion and total leaf area expansion rates are negatively related to SLW or apparent photosynthesis, it may be difficult to identify cultivars that combine a fast rate of leaf expansion with a fast rate of apparent photosynthesis.

Studies on Nitrogen Metabolism in Crop Plants : XVI. Changes in photosynthesis and nitrogen metabolisem in relation to leaf area growth of several rice varieties

Using several rice varieties of rice ecotypes, Aman, Aus, Bulu and Tjereh, including Japonica varieties, it was attempted to clarify the relationships between the leaf area growth, light-saturated photosynthetic rate and soluble protein level, and furthermore to investigate the assimilation of 15N-labelled ammonium nitrogen into the protein fractions in the leaf blades: The results obtained are as follows: 1. In the eleven rice varieties, it was found that there was negative association betwecn single leaf area and light-saturated photosynthetic rate per unit leaf area. 2. The contents of soluble protein per unit leaf area in the leaf blades of the varieties which developed smaller single leaf area were much higher than those of the varieties which developed larger single leaf area. Accordingly, there existed strong negative association between single leaf area and soluble protein content in the leaf blades. This, in turn, appeared to being about the negative correlation between single leaf area and photosynthetic rate as described above. 3. The assimilation of 15N-labelled ammonium nitrogen was studied in the five rice varieties which were contrastive in the leaf area growth. As a result, it was concluded that fraction-1 protein among soluble proteins was accumulated greatly in the leaf blades of the varieties which developed smaller single leaf area as compared with those of the varieties which did larger single leaf area, because protein synthesis predo-minated over protein degradation in the upper leaf blades and protein degradation was suppressed greatly in the lower leaf blades.

Estimation of Leaf Area in Grain Sorghum from Single Leaf Measurements1

AbstractStudies were made to examine the applicability of a common leaf product constant (K‐constant × length × width), for estimating the area of single leaf and it was found that the same constant was applicable for the 3 sorghum genotypes (Sorghum bicolor L Moench) studied (K=0.71). Adaptability of the common leaf product constant for individual leaves according to its position in the plant was also tested by regression analysis, and the same constant was found to be applicable in most cases.Because complete measurement of all leaves of a plant in field trials is time‐consuming and involves prohibitive labor input, the most representative leaf was identified through correlation studies to use it in working out the leaf area index. The largest leaf was found to be the most representative. This representative leaf differed with genotype, depending upon total leaf number. An appropriate factor to work out leaf area of the whole plant from a single leaf was determined. This leaf area factor was found to vary from 4.106 to 5.873 among the sorghum genotypes.