Leaf Area Growth Rate Research Articles

Effectiveness of Commercial Mycorrhizal Inoculants on the Growth of Liquidambar styraciflua in Plant Nursery Conditions

Abstract The effectiveness of several commercial mycorrhizal inoculants on the growth and development of Liquidambar styraciflua (sweetgum) was evaluated. Plants were grown in a nursery potting mix and were inoculated with the mycorrhizal products at the manufacturer's recommended rate. The growth response of mycorrhizal and nonmycorrhizal plants was analyzed at two harvests (8 and 14 weeks after transplanting). Significant differences were found in the growth of L. styraciflua to mycorrhizal colonization with the different commercial products. Fourteen weeks after transplanting, inoculation with products 1 (Earth Roots), 2 (MycoApply endo), and 3 (VAM 80) enhanced the growth of sweetgum relative to the nonmycorrhizal plants. However, plants inoculated with products 2 and 3 had greater leaf area, dry mass and relative growth rates than those inoculated with product 1. Plants of L. styraciflua inoculated with product 4 were less responsive to mycorrhizal colonization and only increased their leaf area relative to the non-inoculated controls. Testing both the infectivity and effectiveness of mycorrhizal fungi is recommended for the successful application of mycorrhizal technology in horticultural practices.

Análise de crescimento de Brachiaria brizantha submetida a doses reduzidas de fluazifop-p-butil

Objetivou-se neste trabalho avaliar o crescimento de Brachiaria brizantha cv. MG5 submetida a doses reduzidas de fluazifop-p-butil, visando a viabilização do consórcio desta espécie com a soja. Os efeitos de três doses do herbicida (0, 18,75 e 37,50 g ha-1) sobre o crescimento de B. brizantha foram avaliados em oito épocas (14, 18, 28, 35, 42, 49, 56 e 70 dias após a emergência - DAE). O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições. Em cada época de avaliação fez-se a coleta das plantas e a determinação da área foliar e da biomassa seca de folhas, colmos e raízes. Com base nesses dados, foram determinadas a taxa de crescimento absoluto e relativo, a taxa de assimilação líquida, a razão de área foliar, a área foliar específica e a razão de biomassa dos colmos e das folhas. Observou-se que doses reduzidas do fluazifop-p-butil promoveram a quebra da dominância apical de B. brizantha, induzindo acentuado perfilhamento. Nessa condição, verificou-se ainda aumento da participação dos colmos na biomassa seca total e redução do comprimento dos colmos em relação ao tratamento sem herbicida. Além disso, as plantas tratadas com fluazifop-p-butil apresentaram folhas mais finas, com redução de área foliar e da taxa de crescimento absoluto, demonstrando a possibilidade da utilização de doses reduzidas de fluazifop-p-butil somente para reduzir o crescimento de B. brizantha.

Wild oat (Avena fatua) habitat and water use in cereal grain cropping systems

Abstract The advent of site-specific weed management has generated research aimed at predicting weed spatial distributions from existing weed maps or correlations with soil properties and edaphic factors. Forecasting the spatial distribution of annual weeds requires knowledge of fecundity, dispersal, management, and suitable habitat distribution. We hypothesized that wild oat habitat was limited by field-scale heterogeneity in plant-available water. We eliminated seed number and dispersal limitations by seeding wild oat in areas with and without historical wild oat patches in three similarly managed spring wheat fields that differed in soil properties and wild oat infestations and were situated within a 160-km radius of Great Falls, MT. Wild oat habitat was quantified by wild oat leaf area growth rate, mature shoot biomass, seeds produced per plant, biomass water use efficiency, and competitive ratio with spring wheat. Soil texture and plot elevation correlated with existing wild oat patch areas in indivi...

Ethylene insensitivity does not increase leaf area or relative growth rate in Arabidopsis, Nicotiana tabacum, and Petunia x hybrida.

The plant hormone ethylene plays a role in various growth related processes. In this detailed study of the vegetative growth of Arabidopsis, Nicotiana tabacum, and Petunia x hybrida plants, we show that ethylene insensitivity does not result in an increased total leaf area or relative growth rate (RGR) under optimal growth conditions. When grown in semiclosed containers, leaf area of ethylene-insensitive plants was larger compared to the wild type. This effect was caused by a buildup of ethylene inside these containers, which inhibited the growth of wild-type plants. Ethylene-insensitive Arabidopsis and N. tabacum plants had a lower biomass, which was mainly the result of a smaller seed mass. RGR of vegetative plants was not affected by ethylene insensitivity, but the underlying components of RGR differed; specific leaf area (leaf area per unit leaf mass) was higher, and unit leaf rate (growth rate per unit leaf area) was lower. The latter was a result of a slower rate of photosynthesis per unit leaf area in the ethylene-insensitive plants.

Effect of leaf extract of resistant teak clone on susceptible clone and vice-versa, on feeding potentiality and larval growth of leaf skeletonizer, Eutectona machaeralis Walker (Lepidoptera: Pyralidae)

Steam distillate leaf extract of resistant teak clone when sprayed on leaves of susceptible clone and vice-versa respectively, exhibited significant (P<0.01) reduction and enhancement of leaf area consumption and growth rate in last instar larvae of E. machaeralis. The findings indicate the role of leaf volatiles in alteration of feeding potentiality and growth of the insect.

Influence of nitrogen and duration of weed interference on corn growth and development

Abstract An improved understanding of the effects of nitrogen (N) on crop–weed interactions is needed for the development of integrated weed management systems where responsible use of N fertilizers is considered. Field experiments conducted in 1999 and 2000 at two locations in eastern Nebraska quantify the effects of N and increasing duration of weed interference on corn growth and development. A naturally occurring population of weeds was allowed to compete with the corn crop for increasing lengths of time and at three rates of N application (0, 60, and 120 kg N ha−1). Weed interference and withholding applied N increased the time to 50% silking by an average of 3.9 and 2.9 d, respectively. Regardless of treatments, relative growth rates of corn leaf area and biomass were maximized between the V1 and V2 growth stages of corn and increased linearly with N rate but were affected to a lesser extent by weed presence. The improvement in early season corn growth with addition of N resulted in greater leaf are...

べたがけに伴う温度変化とコマツナの生長との関係の簡易モデルによる解析

The effect of row cover on the growth of Komatsuna (Brassica campestris L. rapifera group) was evaluated using a simple model describing the relationship between temperature and leaf growth. The model was developed from a growth chamber experiment and shows that a) relative leaf area growth rate (RLGR) varies inversely as the 0.6th power of leaf area (LA) and b) RLGR is related to temperature by a sigmoid curve. Separate field experiments were carried out over six periods of growth and the parameters of the model were derived so as to fit the model to the results of these experiments. The growth-promoting effect of row cover was best described when the model was driven by soil temperature rather than air temperature, and it was therefore concluded that the growth-promoting effect of row cover strongly depends on its ability to warm the soil. The model-aided analysis of field-grown Komatsuna showed that leaf growth under row cover was stimulated most at lower temperatures and in the earlier growth stages. The effect of temperature was explained by the relationship between soil temperature and RLGR, in which the temperature-stimulation of RLGR decreases at higher temperatures. The effect of early growth stage was due to the enhanced rate of soil warming that results from better penetration of solar radiation to the soil surface when canopy leaf area is relatively undeveloped. Although both of these effects are already known empirically, the model-aided analysis used in the present study is able to explain them quantitatively.

Sodium and chloride distribution in roots and transport in three poplar genotypes under increasing NaCl stress

We investigated the effects of increasing soil NaCl on growth, water flow, ion transport and intracellular compartmentation of Na + and Cl − in 1-year-old seedlings of Populus euphratica Oliv. and 1-year-old rooted cuttings of P.× euramericana cv. I-214 (cv. Italica) and P. ‘ popularis 35-44’ ( P. popularis). Relative growth rates of leaf area (RGR A) and shoot height (RGR H) of cv. Italica and P. popularis were severely restricted by increasing salinity, whereas in P. euphratica both were not significantly inhibited . Salinised trees of P. euphratica experienced 10% leaf area loss during a 30-day study, however, cv. Italica and P. popularis shed over 50% of their initial surface area. Leaf necrosis of the two salt-sensitive genotypes (cv. Italica and P. popularis) was attributed to excessive salt accumulation and reduced water loss. The rapid built-up of leaf salt in these two genotypes was mainly the result of high ion concentrations in the transpiration stream. An artificially generated lower shoot-to-root ratio, which was reached by removing approximately 50% of total leaf area from shoots of cv. Italica and P. popularis prior to the salt treatment did not enhance their salinity tolerance since root-to-shoot salt fluxes were largely independent of water flow. Compared with cv. Italica and P. popularis, P. euphratica maintained considerably higher unit leaf transpiration rates with lower salt concentrations in the transpiration stream during the period of salt stress. Therefore, salt tolerance of P. euphratica likely depends on its ability to restrict salt transport to leaves. X-ray microanalysis of root compartments showed that there was genotypic difference in the pattern of ion compartmentation. Cv. Italica exhibited a greater capacity to accumulate salt in cortical vacuoles compared with P. popularis, even though both were considered as salt-sensitive genotypes. P. euphratica was more effective than the other two genotypes to block apoplasmic ion transport and sequester Cl − in cortical vacuoles at high salinity. These limited ion loading into the xylem during radial transport, and thus contributed to the restriction of subsequent axial transport.

Analysing crop yield and plant quality in an intercropping system using an eco-physiological model for interplant competition

An eco-physiological model was used to improve understanding of interplant competition based on physiological, morphological and phenological processes. The model was parameterised based on characteristics of the plants in monocultures and its performance was evaluated for the crop mixtures using experimental data from different growing seasons. A light interception routine accounting for row-geometry was compared to a routine assuming a homogeneous horizontal leaf area distribution. The models simulated the light distribution among the species equally well. The production of the two crops in the mixture was accurately simulated using parameter values based on monoculture growth characteristics. Morphological characteristics of the species such as the relative growth rate of leaf area during early growth and specific leaf area largely determined the competitive strength of the species. Dry matter production of the species, particularly if grown in mixture, was highly sensitive to maximum plant height and radiation use efficiency. Celery was found to be a stronger competitor than leek and clear responses of quality characteristics to plant density in monoculture and mixtures were observed. The model was used to determine ranges of plant densities that enable the intercropping system to meet current quality standards of the component crops.

Growth and physiological responses of Kandelia candel and Bruguiera gymnorrhiza to livestock wastewater

Growth and physiological responses of two mangrove species (Kandelia candel and Bruguiera gymnorrhiza) to livestock wastewater under two salinity conditions (seawater with salinity of 30þ and freshwater) were examined in greenhouse pot-cultivation systems for 144 days. Wastewater treatment significantly enhanced growth of Kandelia candel and Bruguiera gymnorrhiza in terms of stem height, stem basal diameter, leaf production, maximum unit leaf area and relative growth rate. Wastewater discharges and salinity levels did not significantly change biomass partitioning of Kandelia candel, however, more biomass of Bruguiera gymnorrhiza was allocated to leaf due to wastewater discharges. In Bruguiera gymnorrhiza, contents of chlorophyll a and chlorophyll b increased with wastewater discharges but such increase was not observed in Kandelia candel. On the other hand, livestock wastewater increased leaf electric conductance in Kandelia candel but not in Bruguiera gymnorrhiza. The peroxidase activity in stem and root of Kandelia candel under both salinity conditions increased due to wastewater discharges, while the activity in root of the treated Bruguiera gymnorrhiza seedlings decreased under freshwater condition but increased at seawater salinity. The superoxide dismutase activity in treated Bruguiera gymnorrhiza decreased but did not show any significant change in Kandelia candel receiving livestock wastewater.

Elastic and osmotic adjustments in rooted cuttings of several clones of Eucalyptus camaldulensis Dehnh. from southeastern Australia after a drought

Summary Eucalyptus camaldulensis Dehnh., considered as a drought tolerant species, was examined in relation to some mechanisms linked to drought tolerance (cell-wall elastic adjustment and osmotic adjustment) and to the intraspecific variation related to those features. Rooted cuttings of five clones obtained from three different provenances from Australia (Gilgandra: 106, 109; Lake Albacutya: 119, 125; Condamine: 105) were gradually submitted to a water limitation regime. Water stress curtailed relative leaf area growth rate, pre-dawn relative water content (RWC) and noon stomatal conductance (gs) in all clones. Shoot water parameters were estimated at the end of the drought period by pressure-volume (P–V) analysis through a repeat pressurization method. The curves obtained were analyzed by Schulte’s P–V Curve Analysis Program. Drought decreased very significantly the osmotic potential at full turgor (χπFT) and at the turgor loss point (χπTLP), with a significant clone effect: 105 had the lowest values (–2.12±0.04 MPa and –2.39±0.05 MPa). Osmotic adjustment (OA) on average was 0.34±0.02 MPa. Drought increased maximum bulk modulus of elasticity (ɛMAX) by 6.60.7 MPa. There were no clonal differences in either OA or elastic adjustment.Water stress increased significantly turgor potential at full turgor (χFT), and differences between control and stress plants show that the OA recorded did not fully account for the positive changes in turgor of stressed plants. Drought decreased shoot turgid mass/dry mass ratio (TM/DM), again with a significant clone effect: 105 had the lowest value (2.66±0.11). Reduced shoot TM/DM combined with increases in ɛMAXduring stress were indicative of cell wall adjustment, reduced turgor-loss volumes and tightening of the cell walls around the protoplasts, suggesting a cell size reduction. No effects were observed on RWC at the turgor loss point. A regression model that considered ɛMAX and χπFT explained best the response patterns of stressed plants. The mechanisms observed in Eucalyptus camaldulensis that delay growth while maintaining turgor and water uptake allow us to consider it as a dehydration postponement species.

Equations for Predicting Diameter, Height, Crown Width, and Leaf Area of San Joaquin Valley Street Trees

Although the modeling of energy-use reduction, air pollution uptake, rainfall interception, and microclimate modification associated with urban trees depends on data relating diameter at breast height (dbh), crown height, crown diameter, and leaf area to tree age or dbh, scant information is available for common municipal tree species. In this study, tree height, crown width, crown height, dbh, and leaf area were measured for 12 common street tree species in the San Joaquin Valley city of Modesto, California, U.S. The randomly sampled trees were planted from 2 to 89 years ago. Using age or dbh as explanatory variables, parameters such as dbh, tree height, crown width, crown height, and leaf area responses were modeled using two equations. There was strong correlation (adjusted R2 > 0.70) for total height, crown diameter, and leaf area with dbh. Correlations for dbh with age and crown height for several species were weaker. The equations for predicting tree sizes and leaf area are presented and applied to compare size and growth for all species 15 and 30 years after planting. Tree height, crown diameter, and dbh growth rates tended to slow during the second 15 years, but the leaf area growth rate increased for most species. Comparisons of predicted sizes for three species common to Modesto and Santa Monica trees suggest that pruning has a significant impact on tree size and leaf area, potentially more than climate and soil characteristics.

Higher Leaf Area Growth Rate Contributes to Greater Vegetative Growth of F1 Rice Hybrids in the Tropics

The early vigor of hybrid rice (Oryza sativa L.) developed in temperate areas has been mainly attributed to its higher tillering rate. The objective of this study is to identify factors that contribute to greater vegetative growth of Fi hybrid rice recently developed in the tropics. We analyzed data from field experiments conducted from 1994 to1997 in both dry and wet seasons at the International Rice Research Institute farm. Each experiment had one to four pairs of comparisons between best hybrids and best conventional varieties. Parameters used for comparison were tillering rate, leaf area growth rate (LAGR), and crop growth rate (CGR) between transplanting (TR) and midtillering (MT) and also between MT and panicle initiation (PI). In most cases, the hybrids exhibited greater CGR than the conventional varieties, either between TR and MT or between MT and PI or both. The difference in CGR was associated with the difference in LAGR between hybrids and conventional varieties. However, the tillering rate of hybrids was significantly lower than or equal to that of conventional varieties. Therefore, the higher LAGR, independent from tillering, contributed to greater CGR of recently developed F1 hybrid rice in the tropics. The difference in LAGR and CGR between hybrids and conventional varietieswas not associated with tillering. The higher LAGR of the Fl hybrids than that of the conventional varieties could be attributed to their thinner leaf blades.

Compensation of differences in light absorption at the levels of photosynthetic primary processes, CO 2 uptake and growth of tobacco plants

Summary Photosynthesis and growth were studied in tobacco ( Nicotiana tabacum L.) plants exhibiting gradually reduced chlorophyll levels as a result of a glutamate 1-semialdehyde aminotransferase antisense transformation. Measurements of leaf pigmentation, spectral absorptance, chlorophyll fluorescence, CO 2 gas exchange, and leaf area growth were carried out on leaves with an equal state of leaf and plant ontogeny, i.e., the 8 th to 12 th leaf from the top of plants with a total of 22 to 26 leaves. The combination of different growth light intensities (300 and 30 μmol · m −2 · s −1 ) and of differences in chlorophyll accumulation resulted in photon absorption rates of the leaves differing by a factor of 31. As a result of the gradually reduced energy input, rates of electron transport, net CO 2 assimilation, and growth were lowered. However, the extent of this reduction varied between the hierarchic process levels: In relation to leaves of the experimental variant with the highest energy input, leaves with 10 % of the rates of photon absorption and electron transport reached 13 % of the assimilation rate and 53 % of the maximum leaf area growth rate. The data show that the electron transport rate was adjusted to a level slightly in excess of the energy demand of carbon assimilation, and the rate of net CO 2 uptake was in excess of the carbohydrate demand of leaf area growth. The effort of these excessive flows of energy and carbon is the increased stability of the system under conditions of varying resource availability. As a result of excessive flows, differences in energy input restriction are compensated to a certain extent at higher hierarchic levels in leaves. Regarding the whole plant, another compensating mechanism plays a role: The differences between the variants were further diminished, as plants growing under severe energy input limitation reached total leaf areas equal to those of control plants with a delay of 40 days.

Does elevated ozone have differing effects in flowering and deblossomed strawberry?

Fruiting and deblossomed plants of strawberry (Fragaria×ananassa) were exposed to 92 ppb ozone or filtered air in open-top chambers for 69 d. Flower and fruit production, relative growth rate of leaf area, leaf gas exchange and plant biomass were investigated. Ozone caused an initial acceleration in inflorescence production, which was followed by a reduction in inflorescence production, fruit set, and, later, individual fruit weight, although total fruit yield was not affected before the end of the fumigation period. Ozone accelerated leaf senescence and had a greater negative effect on the rate of photosynthesis in older than in younger leaves in fruiting and deblossomed plants, but the response of net photosynthesis to ozone did not differ between the two groups of plants. Relative growth rate of leaf area was the first parameter to be reduced by ozone fumigation, with the effect being significant in fruiting, but not in deblossomed, plants. Final above-ground biomass was also significantly decreased by ozone in fruiting plants, but not in deblossomed plants. Root and crown biomass were not significantly affected by ozone fumigation in either fruiting or deblossomed plants.

Testing the performance of ORYZA1, an explanatory model for rice growth simulation, for Mediterranean conditions

ORYZA1 is an explanatory model to simulate rice growth, development and leaf area index (LAI) under potential production. The present study aims at testing the performance of ORYZA1 for Mediterranean conditions (farming practices, cultivars, weather) for fully irrigated direct-seeded rice. ORYZA1 was calibrated and validated with field data of two cultivars, a short-grain (Tebre) and a long-grain cultivar ( L-202), grown in various years in the Ebro Delta of Spain. Phenological development of the rice crop, daily dry matter production and leaf area development were calibrated. Tebre and L-202 had no significant differences in the total length of the development period. The pre-heading period, however, was longer and the post-heading period shorter in L-202 than in Tebre. This induced differences in translocation characteristics, spikelet number per unit area, weight of the grains and harvest index. The following crop characteristics were similar between cultivars: extinction coefficient (increased with development stage), dynamics of nitrogen distribution, partitioning of assimilates, relative death rate of leaves, relative growth rate of leaf area during exponential growth, specific leaf area and a strongly decreasing specific stem green area. The simulated curve fitted much better the observations, which was clear from a strongly reduced value of RMSE, when considering that LAI comprises the leaf blade area only, without a photosynthetic contribution by stem green area. The model simulated rice growth very accurately until flowering. After flowering, however, divergences appeared and increased especially at the yellow ripe stage. From then on the crop did not grow much more, whereas it continued in the simulation. This reduction of growth rate was usually accompanied by an increase in the relative death rate of leaves and the drying of the grains. The main source of error may be a limited understanding of the ripening and sink limitation processes. A considerable yield gap between potential and observed yield remained. A climatic variability assessment over 10 years, from 1987 to 1996, showed a small but correlated variation ( r=0.7) in both simulated and measured rice yields.

Analyses of assumptions and errors in the calculation of stomatal conductance from sap flux measurements.

We analyzed assumptions and measurement errors in estimating canopy transpiration (E(L)) from sap flux (J(S)) measured with Granier-type sensors, and in calculating canopy stomatal conductance (G(S)) from E(L) and vapor pressure deficit (D). The study was performed in 12-year-old Pinus taeda L. stands with a wide range in leaf area index (L) and growth rate. No systematic differences in J(S) were found between the north and south sides of trees. However, J(S) in xylem between 20 and 40 mm from the cambium was 50 and 39% of J(S) in the outer 20-mm band of xylem in slow- and fast-growing trees, respectively. Sap flux measured in stems did not lag J(S) measured in branches, and time and frequency domain analyses of time series indicated that variability in J(S) in stems and branches is mostly explained by variation in D. Therefore, J(S) was used to estimate transpiration, after accounting for radial patterns. There was no difference between D and leaf-to-air vapor pressure gradient, and D did not have a vertical profile in stands of either low or high L suggesting a strong canopy-atmosphere coupling. Therefore, D estimated at one point in the canopy can be used to calculate G(S) in such stands. Given the uncertainties in J(S), relative humidity, and temperature measurements, to keep errors in G(S) estimates to less than 10%, estimates of G(S) should be limited to conditions in which D >/= 0.6 kPa.

Response of Cassava to Water Deficit: Leaf Area Growth and Abscisic Acid

Cassava (Manihot esculenta Crantz) responds to decreases in water status by pronounced stomatal closure and decreased leaf area growth. Many water deficit responses are thought to be regulated by abscisic acid (ABA). To evaluate the extent to which ABA accumulated in a temporal pattern related to water deficit and leaf area growth, five cassava genotypes were grown in greenhouse conditions and subjected to water deficit and recovery treatments during the vegetative‐growth stage. Young and mature leaves were sampled for analysis of area growth and ABA. Under water deficit, leaves from all genotypes rapidly accumulated large amounts of ABA in both mature and young leaves. Correspondingly, young leaves halted leaf expansion growth and transpiration rate decreased. Young leaves accumulated more ABA than mature leaves in both the control and stressed treatments. The high ABA levels under water deficit were completely reversed to control levels after 1 d of rewatering. This rapid return to control ABA levels corresponded with a rapid recovery of leaf area growth rates. We postulate that the rapid reduction in leaf area growth and stomatal closure observed in our study may be due to cassava's ability to rapidly synthesize and accumulate ABA at an early phase of a water deficit episode.

Ecophysiological characteristics of four maize hybrids and Abutilon theophrasti

Combining empirical research with simulation modelling may improve our understanding of the dynamics of crop:weed competition and for testing hypotheses on the importance of specific traits for enhancing crop performance in mixtures. Two field experiments were conducted to quantify and compare estimates of traits important for radiation interception and utilization in four maize hybrids and Abutilon theophrasti grown in monoculture. Early leaf area growth rate did not vary among maize hybrids within a year, but varied among years. The response of CO2 assimilation rate to absorbed radiation and leaf nitrogen content did not differ among hybrids. Abutilon theophrasti and two old maize hybrids partitioned more new biomass to stem relative to reproductive organs than newer hybrids. Old hybrids had greater specific leaf area during the period of most rapid growth, grew taller, and leaf area was distributed higher in their canopy. Extinction coefficients for diffuse radiation did not differ among hybrids or between years. Results suggest that these four maize hybrids may differ in their ability to intercept incident radiation, which may influence their ability to compete for light.

AFLP mapping of quantitative trait loci for yield-determining physiological characters in spring barley

An amplified fragment length polymorphism (AFLP) map covering 965 cM was constructed using 94 recombinant inbred lines of a cross between the spring barley varieties Prisma and Apex. This map was employed to identify quantitative trait loci (QTLs) controlling plant height, yield and yield-determining physiological characters using an approximate multiple-QTL model, the MQM method. The seven physiological traits were parameters used in a process-based crop-growth model that predicts barley biomass production as affected by daily temperature and radiation. The traits were measured in experiments conducted over 2 years. Except for the relative growth rate of leaf area, all traits examined had at least one QTL in each year. QTLs and their effects were found to vary with developmental stages for one trait, the fraction of shoot biomass partitioned to leaves, that was measured at several stages. Most of the traits were associated, though to different extents, with the denso dwarfing gene (the height-reducing allele in Prisma) located on the long arm of chromosome 3. Some of the QTLs were mapped to similar positions in both years. The results in relation to effects of the dwarfing gene, the physiological basis for QTL×environment interaction, and the relative importance of the parameter traits with respect to yield, are discussed.