Individual Leaf Area Research Articles

Spring leaf flush in aspen ( Populus tremuloides) clones is altered by long-term growth at elevated carbon dioxide and elevated ozone concentration

Early spring leaf out is important to the success of deciduous trees competing for light and space in dense forest plantation canopies. In this study, we investigated spring leaf flush and how long-term growth at elevated carbon dioxide concentration ([CO 2]) and elevated ozone concentration ([O 3]) altered leaf area index development in a closed Populus tremuloides (aspen) canopy. This work was done at the Aspen FACE experiment where aspen clones have been grown since 1997 in conditions simulating the [CO 2] and [O 3] predicted for ∼2050. The responses of two clones were compared during the first month of spring leaf out when CO 2 fumigation had begun, but O 3 fumigation had not. Trees in elevated [CO 2] plots showed a stimulation of leaf area index (36%), while trees in elevated [O 3] plots had lower leaf area index (−20%). While individual leaf area was not significantly affected by elevated [CO 2], the photosynthetic operating efficiency of aspen leaves was significantly improved (51%). There were no significant differences in the way that the two aspen clones responded to elevated [CO 2]; however, the two clones responded differently to long-term growth at elevated [O 3]. The O 3-sensitive clone, 42E, had reduced individual leaf area when grown at elevated [O 3] (−32%), while the tolerant clone, 216, had larger mature leaf area at elevated [O 3] (46%). These results indicate a clear difference between the two clones in their long-term response to elevated [O 3], which could affect competition between the clones, and result in altered genotypic composition in future atmospheric conditions.

Impact of transient chilling temperatures on individual leaf extension and plant leaf area dynamics in maize

Impact of transient chilling temperatures on individual leaf extension and plant leaf area dynamics in maize

Relationships among productivity determinants in two hybrid poplar families grown during three years at two contrasting sites

The objective of this study was to evaluate the environmental, temporal and genetic stability of the relationships between growth and a selection of tree architectural, leaf and phenological traits (selection based on the conclusions of previous studies carried out on the same experimental trial). Therefore, the growth of two hybrid families, Populus deltoides 'S9-2' x Populus nigra 'Ghoy' (D x N family, 180 F(1)) and P. deltoides 'S9-2' x Populus trichocarpa 'V24' (D x T family, 182 F(1)), was investigated during a 3-year period at two sites, i.e., in northern Italy and central France. At the end of the second growing season, all trees were coppiced and the resprouts were thinned to a single stem. At the end of each growing season, stem circumference and height were measured for all F(1) hybrids. The number of sylleptic branches, individual leaf area (LA) and petiole length of the largest leaf along the main stem, production of new leaves, bud flush and bud set were estimated for a selection of genotypes (31 F(1)) per family at each site during the course of the 3-year experiment. The D x T family was clearly the most productive family and displayed the highest heterosis values. However, there appeared to be a compromise between good growth at a given site and stability between the two different sites, both at family and at genotype levels. Particularly, the less performing trees were stable between Italy and France. Among the studied growth components, the number of sylleptic branches and individual LA of the largest leaf along the main stem were the best growth predictors, irrespective of site and family. Growth strategies in terms of leaf development differed between the two families. Hence, leaf production rate was strongly associated with growth of the D x N family only. These results have important consequences for the use of the studied traits as selection criteria in breeding programmes.

The effects of leaf size, leaf habit, and leaf form on leaf/stem relationships in plant twigs of temperate woody species

AbstractQuestion: Do thick‐twigged/large‐leaf species have an advantage in leaf display over their counterparts, and what are the effects of leaf habit and leaf form on the leaf‐stem relationship in plant twigs of temperature broadleaf woody species?Location: Gongga Mountain, southwest China.Methods: (1) We investigated stem cross‐sectional area and stem mass, leaf area and leaf/lamina mass of plant twigs (terminal branches of current‐year shoots) of 89 species belonging to 55 genera in 31 families. (2) Data were analyzed to determine leaf‐stem scaling relationships using both the Model type II regression method and the phylogenetically independent comparative (PIC) method.Results: (1) Significant, positive allometric relationships were found between twig cross‐sectional area and total leaf area supported by the twig, and between the cross‐sectional area and individual leaf area, suggesting that species with large leaves and thick twigs could support a disproportionately greater leaf area for a given twig cross‐sectional area. (2) However, the scaling relationships between twig stem mass and total leaf area and between stem mass and total lamina mass were approximately isometric, which indicates that the efficiency of deploying leaf area and lamina mass was independent of leaf size and twig size. The results of PIC were consistent with these correlations. (3) The evergreen species were usually smaller in total leaf area for a given twig stem investment in terms of both cross‐sectional area and stem mass, compared to deciduous species. Leaf mass per area (LMA) was negatively associated with the stem efficiency in deploying leaf area. (4) Compound leaf species could usually support a larger leaf area for a given twig stem mass and were usually larger in both leaf size and twig size than simple leaf species.Conclusions: Generally, thick‐twigged/large‐leaf species do not have an advantage over their counterparts in deploying photosynthetic compartments for a given twig stem investment. Leaf habit and leaf form types can modify leaf‐stem scaling relationships, possibly because of contrasting leaf properties. The leaf size‐twig size spectrum is related to the LMA‐leaf life span dimension of plant life history strategies.

Summer-drought constrains the phenology and growth of two coexisting Mediterranean oaks with contrasting leaf habit: implications for their persistence and reproduction

This study analyses how coexisting evergreen and deciduous oaks adjust their phenology to cope with the stressful Mediterranean summer conditions. We test the hypothesis that the vegetative and reproductive growth of the winter deciduous (Quercus faginea Lam.) is more affected by summer drought than that of the evergreen [Quercus ilex L. subsp. ballota (Desf.) Samp.]. First, we assessed the complete aboveground phenology of both species during two consecutive years. Shoot and litter production and bud, acorn and secondary growth were monitored monthly. Second, we identified several parameters affected by summer conditions: apical bud size, individual leaf area (LA), leaf mass per area (LMA) and acorn yield in both species, and leaf-fall in Q. faginea; and analysed their variation over 10 years. Q. ilex performed up to 25% of shoot growth and most leaf development during summer, whereas Q. faginea completed most of both phenophases during spring. Secondary growth was arrested in summer under drought conditions. Approximately, 30–40% of bud and 40–50% of acorn growth was undertaken during summer in both species. Summer drought related to differences in LA, LMA and leaf senescence, but not to acorn yield. Both species had similar year-to-year patterns of acorn production, though yields were always lower in Q. faginea. Bud size decreased severely in both species during extremely dry years. In Q. ilex, bud size tended to alternate between years of large and small buds, and these patterns were followed by opposite trends in stem length. In Q. faginea, bud size was more stable through time. Q. ilex was more phenologically active during summer than Q. faginea, indicating a higher tolerance to drought. Furthermore, bud and fruit growth (the only two phenophases that both species performed during summer) were more severely affected by summer drought in Q. faginea than in the evergreen. The differential effects of summer drought on key phenophases for the persistence (bud growth) and colonization ability (fruit production) of both species may have consequences for their coexistence.

Comparisons of Leaf Area Estimation from Linear Measurements of Red Cabbage

Accurate and nondestructive methods to determine individual leaf areas of plants can be useful in physiological and agronomic research. The red cabbage (Brassica oleracea var. capitata L. f. Rubra), cvs. Red Dynasty, Red Rookie, and Schwarzkopf 2, was used. Several characteristics were measured to assess cabbage for their suitability for production in northern Iran. Determination of individual leaf area (LA) of red cabbage was based on predictive equations constructed from measurement of leaf length (L) and width (W) and their combination. Regression analysis of LA vs. L and W revealed several equations that could be used for estimating the area of individual red cabbage leaves. A linear equation having W as the independent variable provided the most accurate estimate of LA. The linear equation (LA = −338.88 + 3.2859W 2) exhibited a high degree of accuracy and precision in estimating LA.

Shoot-foliage relationships in deciduous, semideciduous, and evergreen cerrado tree species

The morphology and the biomass allocation in shoots and leaves were investigated in 15 cerrado tree species with distinct leaf phenology growing under natural conditions. Higher values of leaf/shoot ratio on mass base, individual leaf area, leaf area per shoot, leaf display index, and leaf number per shoot length were found in deciduous than in evergreen species. The differences about shoot-foliage relationship across leaf phenological groups could be explained by plagiotropic shoots on deciduous and by erect shoots in semideciduous and evergreen species. Plagiotropic shoots allow similar irradiance along shoots and high biomass allocation in favor of leaves without foliage self-shading in deciduous tree species. The structural differentiation between short and long shoots was indicated by an exponential relationship between leaf display index and shoot length in all deciduous, in three semideciduous, and in two evergreen species. Therefore, especially in deciduous, the short shoots had higher leaf area per unit of length than the long shoots. The differentiation between short and long shoots depends on the shoot length in deciduous because of the leaf number on shoot is predetermined in buds. Contrastingly, the leaf neo-formation in semideciduous and in evergreen tree species keeps the shoot-leaf relationship per shoot length more constant, because of the foliage being produced according to the shoot growth during the year. In conclusion, the foliage persistence, the shoot inclination, the type of leaf production and the resources allocation between autotrophic and heterotrophic vegetative canopy parts are interdependent in cerrado tree species across different leaf phenological groups.

A Method for Estimating Sago Palm (Metroxylon sagu Rottb.) Leaf Area after Trunk Formation

It is important to measure the individual leaf area and leaf area index (LAI) of sago palm (Metroxylon sagu Rottb.) to determine the appropriate planting density and maintain populations that are highly productive with regard to starch production. However, the accurate estimation of sago leaf area from the entire leaf profile or the projecting area of the plant is not possible. Thus, we developed a method for estimating leaf area of sago palm after trunk formationby integrating the leaflet areas. All leaflets were diagrammatically converted to rectangles, each having the same area asthat of the corresponding leaflet, and these rectangles were arranged on the rachis to initiate the shape of a leaf without overlapping leaflets and gaps between their bases and between their tips. The leaf shape thus produced by the arrangement of these rectangles was represented as ellipsoidal in the apical half and as trapezoidal in the basal half. The ratiosof the estimated to the actually measured area of the apical and the basal half of the leaf were 99−107% and 94−108%, respectively. The ratio of the estimated area of the whole leaf to the measured area was 98−104%. From these results, the method for estimating the whole leaf area by converting the leaflets diagrammatically to rectangles, andcalculating the area as the sum of the ellipsoidal apical half and trapezoidal basal half, is considered to be accurate and simple.

Leaf Area Estimation Model for Small Fruits from Linear Measurements

Accurate and nondestructive methods to determine individual leaf areas of plants are a useful tool in physiological and agronomic research. Determining the individual leaf area (LA) of small fruit like raspberry (Rubus idaeus L.), redcurrant (Ribes rubrum L.), blackberry (Rubus fruticosus L.), gooseberry (Ribes grossularia L.), and highbush blueberry (Vaccinium corymbosum L.) involves measurements of leaf parameters such as length (L) and width (W) or some combinations of these parameters. A 2-year investigation was carried out during 2006 (on seven raspberry, seven redcurrant, six blackberry, five gooseberry, and two highbush blueberry cultivars) and 2007 (on one cultivar per species) under open field conditions to test whether a model could be developed to estimate LA of small fruits across cultivars. Regression analysis of LA versus L and W revealed several models that could be used for estimating the area of individual small fruit leaves. A linear model having LW as the independent variable provided the most accurate estimate (highest R 2, smallest mean square error, and the smallest predicted residual error sum of squares) of LA in all small fruit berries. Validation of the model having LW of leaves measured in the 2007 experiment coming from other cultivars of small fruit berries showed that the correlation between calculated and measured small fruit berries LAs was very high. Therefore, these models can estimate accurately and in large quantities the LA of small fruit plants in many experimental comparisons without the use of any expensive instruments.

Combined Effects of Temperature and Carbon Dioxide on Plant Growth and Subsequent Seed Germinability of Silene noctiflora

Effects of global climate change on invasive alien species of plants and on the resulting progeny have received little attention. We examined the combined effects of temperature and carbon dioxide (CO2) on plant growth and physiological characteristics, reproductive yield components, and subsequent germination patterns of fresh‐ and dry‐stored seeds of night‐flowering catchfly (Silene noctiflora). Plants were grown under two temperature regimes (22°/18°C and 28°/24°C) at ambient (370 μmol mol−1) and elevated (740 μmol mol−1) CO2 concentrations in controlled‐environment growth chambers. Higher temperature reduced plant height; average individual leaf area; capsule length, width, and mass; sound seed number; and mass per capsule but increased specific leaf mass. Elevated CO2 increased single sound seed mass. Higher temperature decreased both percentage and rate of germination, whereas elevated CO2 decreased germination percentage but increased germination rate. Seed germination increased with storage duration. Higher temperature increased transpiration. However, elevated CO2 decreased transpiration but increased net CO2 assimilation and water use efficiency. Elevated CO2 increased chlorophyll b but decreased chlorophyll a:b ratio. Ethylene production was enhanced by increased temperature. We conclude that despite the negative effects of higher temperature on some plant characteristics, S. noctiflora has the potential to thrive under conditions of climate change.

Leaf allometry and prediction of specific leaf area (SLA) in a sugar beet (Beta vulgaris L.) cultivar

Sugar beet cv. Rizor was grown for five growing seasons (2002-2006) in field conditions in Thessaly, central Greece. A total of 55 samplings took place during the growing seasons and allometric growth of the leaves was monitored. Highly significant (p<0.001) quadratic relationships were found between individual leaf mass (LM), individual leaf area (LA), aboveground dry biomass (ADB), and leaf area index (LAI). Only the LM-LA relationship (LA = 43.444 LM2 - 10.693 LM + 118.34) showed a relatively high r 2 (0.63) and thus could be used for prediction of LA. Specific leaf area (SLA) was significantly related with leaf water content (LWC) (SLA = 26 279 LWC2 - 44 498 LWC + 18 951, r 2 = 0.91, p<0.001) and thus LWC could be a good indirect predictor of SLA in this cultivar.

Linking population density and habitat structure to ecophysiological responses in semiarid Spanish steppes

We have studied the underlying factors responsible for the heterogeneous ecophysiological status of a semiarid Stipa tenacissima L. steppe in a subcatchment of SE Spain by assessing population composition and habitat structure of S. tenacissima stands. To do this, we measured and estimated 18 variables (11 biotic and seven abiotic) in 15 plots randomly distributed in the subcatchment, and then zoned this area by plot affinity using PCA. This analysis produced three sectors determined mainly by S. tenacissima cover and soil depth variables. The linear relationship fitted between S. tenacissima tussock biomass and tussock density in monospecific stands (both logarithmic) indicated a curve close to −1, suggesting that the system is close to the maximum constant yield state. Ecophysiological measurements (gas exchange, fluorescence and individual leaf area index) were taken in two periods with different water availability in a representative plot in each sector. The intraspecific competition (inferred from the density dependence of green biomass) and rock outcrops were the main factors influencing the ecophysiological status in the study area. While, in the wet season, intraspecific competition regulated water consumption in zones where S. tenacissima tussocks (monospecific stands) are dominant, during the dry season, stands in zones with extensive rock outcrops and stone cover (tussocks in “soil pockets”) had no access to non-rainfall water gains because of the adjacent bare soil, and so in these stands, gas exchange was lower and photoinhibition higher. This article stresses the importance of considering the connection between tussocks and bare-ground interspace in the functional and structural analysis of semiarid steppes.

Solar radiation interception and canopy expansion of sweet corn in response to phosphorus

Insufficient phosphorus (P) availability decreases the yield of Zea mays, particularly for sweet corn crops grown in cool environments. This research examined the mechanisms of yield reductions with initial emphasis on canopy expansion processes that affect the interception of solar radiation. Experiments in two consecutive seasons (2001/2002 and 2002/2003) were grown at a low P site (Olsen P = 6 μg ml −1) at Lincoln, New Zealand. Each experiment contained five rates of P application. In 2001/2002 rates of 0, 50, 100, 150, or 200 kg P ha −1 were applied. In 2002/2003 an additional 0, 0, 10, 20 or 40 kg P ha −1 was applied to the same plots producing total P treatments of 0, 50, 110, 170 or 240 kg P ha −1 summed over the two seasons. When P availability was limited (0 or 50 kg P ha −1) the rates of leaf tip and fully expanded leaf appearance were slower in both seasons. Phyllochrons (°Cd leaf tip −1) were ∼5 °Cd longer in crops that received 0 kg P ha −1 than those fertilised with ≥100 kg P ha −1. The area of individual leaves was also reduced by low P inputs but the ranking of leaf area by main stem leaf position was conservative. The leaf area of the largest leaf of the unfertilised crops was at least 22% less than the maximum measured leaf area in both seasons. In contrast, P fertiliser application had no effect on leaf senescence. The rate of leaf appearance per plant, individual leaf area and plant population were integrated to calculate green leaf area index (GLAI) and to estimate accumulated radiation interception (RI cum) for these crops. The total RI cum throughout the season in the unfertilised crops was 12–28% less than for those crops that received ≥100 kg P ha −1 in both seasons. This difference partly explained the differences in crop biomass production in response to P availability. A sensitivity analysis showed that RI cum was equally sensitive to changes of the rate of leaf appearance and the area of individual leaves in response to P supply. Both processes need to be incorporated in mechanistic models of P effects on Z. mays which can be used to design efficient P fertiliser strategies.

Contributions of foliage distribution and leaf functions to light interception, transpiration and photosynthetic capacities in two apple cultivars at branch and tree scales

Both the spatial distribution of leaves and leaf functions affect the light interception, transpiration and photosynthetic capacities of trees, but their relative contributions have rarely been investigated. We assessed these contributions at the branch and tree scales in two apple cultivars (Malus x domestica Borkh. 'Fuji' and 'Braeburn') with contrasting architectures, by estimating their branch and tree capacities and comparing them with outputs from a radiation absorption, transpiration and photosynthesis (RATP) functional-structural plant model (FSPM). The structures of three 8-year-old trees of each cultivar were digitized to obtain 3-D representations of foliage geometry. Within-tree foliage distribution was compared with shoot demography, number of leaves per shoot and mean individual leaf area. We estimated branch and tree light interception from silhouette to total leaf area ratios (STAR), transpiration from sap flux measurements and net photosynthetic rates by the branch bag method. Based on a set of parameters we previously established for both cultivars, the outputs of the RATP model were tested against STAR values, sap fluxes and photosynthetic measurements. The RATP model was then used to virtually switch foliage distribution or leaf functions (stomatal and photosynthetic properties), or both, between cultivars and to evaluate the effects on branch and tree light interception, transpiration and photosynthetic capacities in each cultivar. 'Fuji' trees had a higher proportion of leaf area borne on long shoots, fewer leaves per unit shoot length and a larger individual leaf area than 'Braeburn' trees. This resulted in a lower leaf area density and, consequently, a higher STAR in 'Fuji' than in 'Braeburn' at both branch and tree scales. Transpiration and photosynthetic rates were significantly higher in 'Fuji' than in 'Braeburn'. Branch heterogeneity was greater in 'Braeburn' than in 'Fuji'. An analysis of the virtual switches of foliage distribution or leaf function showed that differences in leaf spatial distribution and functions had additive effects that accounted for the lower transpiration and photosynthetic rates of branches and trees of 'Braeburn' compared with 'Fuji'. Leaf distribution had a more important role at the branch scale than at the tree scale, but the leaf function effect exceeded the leaf distribution effect at both scales. Our study demonstrated the potential of FSPM to disentangle physiological differences between cultivars through in silico scenarios.

Interactive Effects of Carbon Dioxide and Water Stress on Potato Canopy Growth and Development

Reductions in potato (Solanum tuberosum L.) canopy growth are observed with mild water stress. Potato growth is enhanced by elevated atmospheric carbon dioxide ([CO2]), but interactions of [CO2] and water stress on canopy formation and dry matter partitioning have not been studied. Two soil‐plant‐atmosphere research (SPAR) experiments were conducted at 370 or 740 μmol mol−1 [CO2] and six different irrigations from 10 to 100% of the daily water uptake of the control. Increases in plant length from 23 to 111 cm at 60 d after emergence (DAE), leaf appearance duration from 38 to 71 d, leaf appearance rate from 0.5 to 0.93 leaves d−1, individual leaf area from 50 to 175 cm2, and lateral branch elongation were observed as irrigation increased. Values were generally smaller for elevated [CO2] plants under water stress. Biomass increased with irrigation from 73 to 346 g plant−2. The percentage allocated to the canopy increased with irrigation from 50 to 80% in ambient and 30 to 80% in elevated [CO2]. Despite decreased canopy size, elevated [CO2] plants produced similar total biomass, but higher yield, at most irrigations. Reduced canopy mass in elevated [CO2] plants was attributed to suppressed lateral branch development due to an interactive effect of [CO2] and water stress on tuber sink strength. These results indicate that water stress predicted by climate change models will be mediated somewhat under [CO2] enrichment.

Removal of understory dwarf bamboo (Sasa kurilensis) induces changes in water-relations characteristics of overstory Betula ermanii trees

We investigated how removal of understory dwarf bamboo (Sasa kurilensis Makino et Shibata) affected growth and water use of young Betula ermanii Cham. trees in a secondary forest in northern Japan. We compared current-year shoot morphology, leaf water-relations characteristics, and whole-tree water use of B. ermanii trees growing with dwarf bamboo in the understory (intact plot) to those of trees growing where dwarf bamboo was experimentally removed (removal plot). Current-year shoot length and internode frequency increased, while internode length and individual leaf area decreased in response to dwarf bamboo removal. Carbon isotope composition (δ13C) of leaves did not change indicating that leaf water-use efficiency was unaffected by the presence/absence of dwarf bamboo. Pressure–volume analysis indicated that leaves in the removal plot had lower water uptake ability. During mid-summer, trees in the removal plot sustained high sap flow velocity after peaking at midday, while that of trees in the intact plot declined. In addition, whole-tree sap flux and soil-to-leaf hydraulic conductance were both higher for trees in the removal plot. We inferred that the observed changes reflect hydraulic homeostasis of B. ermanii trees to maintain constant water-use efficiency in response to belowground competition with dwarf bamboo. Removal of dwarf bamboo is, therefore, an effective silvicultural prescription to enhance growth of overstory trees by relieving belowground competition for soil water.

Ecological responses of Primula nutans to centimeter‐scale topographic and environmental variability in an alpine wetland

AbstractPrimula nutans Georgi is a herbaceous species broadly distributed in wetlands on the Qinghai–Tibetan Plateau. These wetlands are often spatially highly heterogeneous because of their hummock‐and‐hollow microtopography. To address how P. nutans can be so broadly distributed on these wetlands, we examined ramet distribution, abundance, and growth performance in environmentally variable microsites at the centimeter scale. P. nutans showed significantly higher ramet density on the south‐orientated microsites than on the north‐orientated microsites. With increasing relative microsite elevation on the hummocks, ramet density increased significantly, but individual leaf area decreased significantly. Principle component analysis and multiple regression analysis indicated that microsites at higher elevations tend to have higher light availability and higher ramet density. The study suggests that P. nutans shows high plasticity in the distribution, abundance, and growth performance in response to the microtopography at the centimeter scale, which may contribute to the broad distribution of the species in the hummock‐and‐hollow wetlands in harsh alpine environments on the Tibetan Plateau.

Accurate and Rapid Technique for Leaf Area Measurement in Medlar (Mespilus germanica L.)

Accurate measurements of leaf area are important for agronomic and physiological studies. Deter- mining the individual leaf area (A) of medlar (Mespilus germanica L.) involves measurements of leaf parameters, such as length (L) and width (W), or some combinations of these parameters. A two-year investigation was car - ried out in 2005 (on seven genotypes) and in 2006 (on one cultivar) underopen-field conditions to test whether a model could be developed to estimate leaf area across genotypes. Regression analyses of A versus Land W revea- led several models could be used for estimating the area of individual medlar leaves. A linear model having LW as the independent variable (A = 1.81 + 0.68 LW) provided the most accurate estimate (R 2 = 0.981, MSE = 7) of medlar leaf area. Validation of the model having LW of leaves from another genotype measured in the 2006 expe- riment showed that the correlation between calculated and measured areas was very high. Using the selected model, agronomists and physiologists can accurately and reliably estimate the leaf area of medlarwithout the use of expensive instruments.

Okra ve Normal Yapraklı Pamuklarda (Gossypium hirsutum L.) Bazı Fizyo-Morfolojik Oluşumların Verim ile Olan ilişkileri

Pamukta yaprağın şekli, büyüklülüğü, sayısı ve alanı bitkinin fotosentetik faaliyetlerini ve dolayısıyla verimliliğini etkileyen faktörlerdendir. Çalışmada, okra ve normal olmak üzere iki farklı yaprak şekline sahip dört pamuk (Gossypium hirsutum L.) çeşidinde yaprak sayısı, ortalama tek yaprak alanı, yaprak alanı indeksi, yaprak klorofil miktarı, bitki boyu ve kütlü pamuk verimi özellikleri incelenmiştir. Okra ve normal yapraklı çeşitlerde, incelenen özelliklerin kütlü pamuk verimi ile olan ilişkileri, korelasyon analizleri yapılarak belirlenmiştir. Normal yapraklı çeşitler, ortalama tek yaprak alanı, yaprak alan indeksi, bitki boyu, meyve dalı sayısı ve kütlü verimi yönünden daha iyi sonuçlar vermişlerdir. En yüksek yaprak klorofil değeri, 50.54 ile Maraş 92 çeşidinden en düşük ise 46.44 ile Dicle 2000 çeşidinden elde edilmiştir. Kütlü pamuk verimi yönünden Maraş 92 pamuk çeşidi, 509.93 kg.da-1 ile en yüksek değere, Siokra % okra yapraklı pamuk çeşidi ise 365.56 kg.da-1 ile en düşük değere sahip olmuştur. İncelenen özellikler arası ilişkilerde ise, pamuk kütlü verimi ile yaprak sayısı arasında olumsuz ve önemli; yaprak alanı indeksi ile olumlu ancak önemsiz ilişkiler saptanmıştır.

Modelling foliage characteristics in 3D tree crowns: influence on light interception and leaf irradiance

Because of the difficulty and time involved in making exhaustive measurements of the geometric parameters of large tree crowns, simplifying hypotheses are often used in 3D virtual plant modelling, but the effects on the radiation balance of each approximation are rarely assessed. Three hybrid walnut trees aged 7–9 years were digitized to analyse the effect of the crown geometric variables on light capture. The six studied variables were: (1) leaf area, (2) number of leaves per annual shoot, (3) position of leaves, (4) orientation of leaves, (5) leaflet inclination, and (6) lamina shape. For each variable, a sensitivity analysis compared a reference, based on observed values, with scenarios consisting of simplifying hypotheses. The total incident light intercepted during a bright day and the distributions of leaf irradiance were calculated using the Archimed radiative transfer model. Since some of the crown parameters were generated stochastically, the radiation simulations were repeated until results stabilised. Simplified models can be used to calculate with satisfactory results individual leaf area and number of leaves per shoot. Conversely, differentiating statistical distributions of individual leaf area between short and long shoots is more difficult and may generate errors up to 30%. Leaf clumping is a determining factor and requires correct grouping of leaves around the annual shoots bearing them. The effect of position of leaves along the shoot is less than 2%. Simple statistical distributions are adequate for representing leaf angle. Finally, the effect of specific leaf geometry is very important, but it can be approached using a limited number of representative leaf shapes.