Dry Matter Accumulation Patterns Research Articles

Genetic variability in nodulation and root growth affects nitrogen fixation and accumulation in pea.

Legume nitrogen is derived from two different sources, symbiotically fixed atmospheric N(2) and soil N. The effect of genetic variability of root and nodule establishment on N acquisition and seed protein yield was investigated under field conditions in pea (Pisum sativum). In addition, these parameters were related to the variability in preference for rhizobial genotypes. Five different spring pea lines (two hypernodulating mutants and three cultivars), previously identified in artificial conditions as contrasted for both root and nodule development, were characterized under field conditions. Root and nodule establishment was examined from the four-leaf stage up to the beginning of seed filling and was related to the patterns of shoot dry matter and nitrogen accumulation. The genetic structure of rhizobial populations associated with the pea lines was obtained by analysis of nodule samples. The fraction of nitrogen derived from symbiotic fixation was estimated at the beginning of seed filling and at physiological maturity, when seed protein content and yield were determined. The hypernodulating mutants established nodules earlier and maintained them longer than was the case for the three cultivars, whereas their root development and nitrogen accumulation were lower. The seed protein yield was higher in 'Athos' and 'Austin', the two cultivars with increased root development, consistent with their higher N absorption during seed filling. The hypernodulating mutants did not accumulate more nitrogen, probably due to the C cost for nodulation being higher than for root development. Enhancing exogenous nitrogen supply at the end of the growth cycle, by increasing the potential for root N uptake from soil, seems a good option for improving pea seed filling.

Post-flowering dry matter accumulation and partitioning and timing of crop maturity in chickpea in western Canada

A field experiment aimed at determining whether timing of crop maturity was related to patterns of dry matter (DM) accumulation and partitioning to reproductive organs in chickpea was conducted at different locations in Saskatchewan over two seasons, 2003 and 2004. Five genotypes 272-2, 298T-9, E100Ym, CDC Anna, and CDC Frontier were grown in a RCB design with four replications. Beginning at 60 d after seeding (DAS) and every 15 d following, plant samples were taken and separated into stem, leaf and pod fractions. Then dry weights of the sample fractions were determined. Total DM production showed an increasing trend over sampling dates, but the increase was at a decreasing rate beginning in mid-season. The early genotype 272-2 had a pattern of total DM accumulation similar to the others, but had significantly smaller vegetative (stem plus leaf) DM accumulation during the latter part of the growth period. This shows a relatively high proportion of DM partitioning to pod for 272-2. Also, the partitioning of resources to reproductive parts (allometric partitioning) and pod harvest index were each negatively associated with days to maturity, implying that assimilate partitioning for maximum pod DM is important for early maturity in chickpea in western Canada. Key words: days to maturity, post-flowering growth, dry matter, dry matter partitioning, pod harvest index

Effects of varied water regimes on root length, dry matter partitioning and endogenous plant growth regulators in sunflower (Helianthus annuus L.)

A field experiment was conducted to quantify the effect of varied water regimes on root length, partitioning of dry matter and plant growth regulators by using sunflower genotypes differing in maturity and drought tolerance. Significant depressing effect of drought stress was evident on traits (i.e., reproductive dry matter, leaf area index and cytokinin concentrations in leaves). However, root/shoot, reproductive/vegetative ratios and Abscisic acid (ABA) concentration were found to increase under drought stress. Drought stress also changed the dry matter accumulation pattern of genotypes. In most cases it reduced the days to reach the maximum peak showing early senescence. ABA was identified as a multi-functional plant growth regulator under drought stress, causing early senescence of plants and translocation of assimilates to the roots and reproductive part while root growth under drought stress was explained by the indole-acetic acid (IAA) concentrations. Maintaining higher cytokinin contents were involved in accumulation of higher reproductive dry matter under drought stress. Although ABA and IAA were both involved in the development of defense responses during the adaptation and survival to drought stress but higher productivity under drought stress was only realized through maintaining higher cytokinin contents.

Evaluation of the CSM-CROPGRO-Peanut Model in Simulating Responses of Two Peanut Cultivars to Different Moisture Regimes

Drought is a major yield limiting factor in peanut production. Characterization of drought stress patterns of major production areas and information on crop responses to different levels of drought stresses are needed for the development of appropriate management strategies for individual locations. The CSM-CROPGRO-Peanut model could help in obtaining the required information, but its capability in predicting crop responses to different levels of drought stress needs to be firstly established. The objective of this study was to evaluate the capability of the CSM-CROPGRO-Peanut model in simulating the responses of two peanut cultivars to three levels of soil moisture regimes. The experiments were conducted under field conditions in the dry seasons of 2004 and 2005 at the Field Crop Research Station of Khon Kaen University in northeast Thailand. A split-plot in a randomized complete block design with 4 replications was used. Three levels of soil moisture (field capacity, 2/3 available water and 1/3 available water) were assigned to main-plots and two peanut cultivars (KK60-3 and Tainan 9) were arranged in sub-plots. Data collected on growth and development of the two peanut cultivars under the three soil moisture regimes were compared with the corresponding simulated data from model simulation using the CSM-CROPGRO-Peanut model. The results showed that the model performed fairly in simulating phonological development and patterns of dry matter accumulation but performed reasonably well in predicting the final biomass and pod yields of the two peanut cultivars under the three soil moisture regimes. The model, however, could predict the relative yield reductions from drought stress of the individual peanut cultivars quite accurately and could provide information on the time of occurrence and severity of water stress during the cropping period. These results indicate that the CSM-CROPGRO-Peanut model is sufficiently capable to be used in generating the required information for determining appropriate managements of drought stress

Seasonal Changes in Dry Matter Partitioning, Yield, and Crude Protein of Intermediate Wheatgrass and Smooth Bromegrass

Seasonal patterns of dry matter partitioning and nutritive value of leaf and stem components of grass species is important for selecting species for planting, planning grazing strategies, and making management decisions. Our objective was to compare dry matter yield and crude protein (CP) yield of blade, sheath, and stem fractions of intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and smooth bromegrass (Bromus inermis Leyss.) during the growing season. Intermediate wheatgrass and smooth bromegrass were sampled on a weekly basis from 14 May to 25 June in 1997 and from 5 May to 23 June in 1998 at Lincoln, NE. Samples were separated into blade, sheath, stem, and inflorescence components and yield and concentration of CP were determined. Smooth bromegrass tended to have greater blade and stem yield than intermediate wheatgrass during the 1997 and 1998 sampling periods. Yield of sheath was similar between species. Crude protein yield of blade and stem was also greater for smooth bromegrass than intermediate wheatgrass in both years. Sheath CP yield was greater for intermediate wheatgrass in 1998. Both species followed a similar pattern of dry matter accumulation; however, intermediate wheatgrass dry matter accumulation, especially stem, tended to be 1 to 2 wk behind smooth bromegrass. Differences in dry matter partitioning, yield, and CP in these two species illustrates the advantages having a complement of forage species. Choosing a diversity of species with differing growth habits would be beneficial for improving the distribution of forage yield and quality to match the seasonal demand of grazing livestock.

The Response of Basil Accessions to Date of Planting in North Alabama

Basil (Ocimum sp.), belonging to the mint family, Lamiaceae (Labiatae), is a popular herb grown for the fresh market or for its dried aromatic leaves, which are used as a spice or in potpourris. In Asian countries, basil, particularly O. tenuiflorum, is better known as a medicinal plant species used for treating ailments ranging from colds to complex diseases such as cancers and diabetes. In the United States, however, it has a limited acceptance as a fresh-market herb. There is much potential for developing basil as a medicinal plant to cater to the growing herbal medicinal products industry. A field trial was therefore conducted to determine optimum date of planting basil in Alabama. Six-week-old seedlings were transplanted from the greenhouse into field plots arranged in a split-plot design with four replications. Planting dates at monthly intervals beginning in April were the main plots and three Ocimum accessions, Ames 23154, Ames 23155, and PI 288779 were sub-plot treatments. The accessions were compared for growth, leaf area development, light interception, canopy cover, and dry matter accumulation and partitioning pattern over planting dates. Ames 23154, with greater canopy cover (98.5%) and photosynthetically active radiation interception (96.1%), also produced higher total plant biomass than other accessions. Accession PI 288779 appeared to partition greater dry matter to leaves, which are the primary source of bioactive compounds in basil. Among planting dates, second (May) date of planting appeared to be optimum for both total biomass and leaf dry matter production. Genotypic variation f or dry-matter partitioning and relationships among agronomic parameters as influenced by planting date will be discussed in this presentation.

Acúmulo de macro e micronutrientes nas inflorescências e frutos da lichieira "Bengal"

Estudou-se o acúmulo de macro e micronutrientes durante o desenvolvimento da inflorescência e do fruto da lichieira "Bengal". Inflorescências e frutos foram colhidos quinzenal ou semanalmente, sendo os frutos separados das inflorescências a partir de 35 dias após a antese e em pericarpo, semente e arilo a partir de 77 dias após a antese. Os macro e micronutrientes foram avaliados em cada componente. O acúmulo dos macro e micronutrientes estudados na inflorescência e no fruto da lichieira "Bengal" seguiu, basicamente, os respectivos padrões de acúmulo de matéria seca nestes órgãos. N e K foram os nutrientes presentes em maior quantidade na inflorescência/haste floral. Aos 112 dias após a antese, época da colheita comercial dos frutos, o arilo foi o maior responsável pelo acúmulo de K (58,6%), P (56,3%), N (43%), S (36,7%) e Cu (43,5%). No pericarpo, observaram-se os maiores conteúdos de Ca (75,6%), Fe (71,1%), Mg (47,4%) e Mn (58,1%) e, na semente, verificou-se o maior percentual de Zn (34,3%). A ordem de exportação de nutrientes pelos frutos aos 112 dias após a antese foi a seguinte: K > N > Ca > Mg > P > S > Fe > Mn > Zn > Cu.

Effects of water stress on dry matter content and partitioning in four grapevine cultivars (<em>Vitis vinifera</em> L.)

<p style="text-align: justify;">Three-year-old grapevines of four cultivars (Garnacha tinta (Grenache noir), Tempranillo, Chardonnay and Airén) were grown on 35 L container under full irrigation and restricted irrigation conditions in order to determine the effect of water stress on carbohydrate allocation. Total grapevine dry matter was measured at pruning, fruitset, veraison and harvest. Roots, wood, shoots, leaves and clusters were dried separately. Shoots were the most affected organs by water stress, while wood was the least affected. Vines under water stress partitioned more dry matter to wood and roots to the detriment of fruits and shoots. The period from fruitset to veraison was the most active for dry matter accumulation under conditions of stress, whereas non-water stressed vines accumulated more dry matter from veraison to harvest. Under both irrigation treatments, fruits competed with roots for dry matter partitioning. Irrigation treatment and cultivar determined fruit size. Fruit size determined dry matter partitioning between organs and the dry matter accumulation pattern.</p>

DRY MATTER AND NITROGEN ACCUMULATIONS AND PARTITIONING IN TWO POTATO CULTIVARS

ABSTRACT Potato plant dry matter and nutrient accumulation and partitioning patterns into various parts of the plant are important to fine tune management practices that optimize the nutrient uptake efficiency and tuber production-dates printpubdate="07/01/2002". Accumulation and partitioning of dry matter and nitrogen (N) during the growing period were evaluated in this four year study for two potato cultivars in high yielding production-dates printpubdate="07/01/2002" conditions in the Columbia Basin production-dates printpubdate="07/01/2002" region in Washington, under irrigated farming. Studies were conducted on a Quincy fine sand, which represents a typical potato production-dates printpubdate="07/01/2002" soil in this region. A full season indeterminate potato cultivar (Russet Burbank) and an early maturing determinate cultivar (Hilite Russet) were used in this study. Partitioning of assimilates into the tuber was similar for both cultivars. The tuber weight accounted for 76 to 87% of total plant weight, while that of stem and leaf weight accounted for 3 to 11, and 9 to 13%, respectively. Tuber weight increased rapidly during 60 to 100 days after planting. Nitrogen content in the tuber, in relation to the total N in the plant, accounted for 81 to 86, and 83 to 89%, for the Hilite Russet and Russet Burbank cultivars, respectively. Nitrogen in the leaves comprised 6 to 18%, and in the stem 3 to 5% of the total plant N. Prior to senescence of the vines, total N in the plants (excluding roots) accounted for up to 350 kg ha−1. At this growth stage, the N in tubers, leaves, and stems represented 68.6, 19.4, and 12.0%, respectively. The above information is useful for N management with the knowledge of soil residual N and availability of N from mineralization of crop residue during the crop growing season.

Changes in moisture, dry matter and soluble sugars of dry-on-the-vine raisins with special reference to sorbitol

SummaryThe moisture, dry matter and soluble sugar composition of Vitis vinifera L. advanced selections of dry-on-the-vine raisins were determined over several seasons. Moisture loss from post-veraison berries occurred in a graduated stepwise manner, with a rapid decline from an initial 86±2% to 60±5% 108 d from first bloom, a slower loss and a final accelerated loss to 25±4% after 151 days from first flowering. The pattern of dry-matter accumulation was similar in large, medium, or small berries but dry matter was higher in large (0.65±0.04 g dry wt. per berry) than medium (0.52±0.03 g dry wt. per berry) or small (0.36±0.03 g dry wt. per berry raisin). Incipient browning was seen with raisin formation at the distal berry region with a higher sugar concentration than in the proximal (pedicel) region. Sucrose in the raisins exhibited two maxima, one (1.4±0.2 mg g–1 fresh wt.) 96 d from first bloom, and a second (2.4±0.4 mg g–1 fresh wt) 123 d after first bloom, with each maximum occurring before the rise in glucose, fructose, and sorbitol, and decreasing as these sugars increased. Sorbitol was not detected initially in mature berries, but increased in raisins. It was proposed that sorbitol or its biosynthetic enzyme might be useful for determining raisin harvest. Raffinose and sucrose contents of the peduncle were higher than raisins and may indicate a role of these sugars in the physiology of the peduncle.

Effect of manure on accumulation of dry matter, nitrogen, and phosphorus by soybean

Manure application for soybean [Glycine max (L.) Merr.] production is being considered by livestock producers, but the manure's influence on dry matter (DM), nitrogen (N), and phosphorus (P) accumulation is not well documented. The objectives of this study were to measure N, P, and DM accumulation patterns and quantities by three genetically-different soybean varieties. Two preplant, sweep-injected manure application rates and a control were main plot treatments and three soybean varieties were subplots at seven experimental sites in 1996 and 1997. Starting in mid-June and continuing on a 15-d schedule until maturity, whole-plant samples were collected, dried, weighed, and analyzed for N and P. Plant DM increased with increasing manure rates at each sampling after mid-June. Nitrogen concentration differences among manure rates were greatest early in the season and diminished with time, whereas P concentration differences were consistent throughout the sampling period. Compared to the control treatment, manure resulted in an average of 25% more N accumulation at the first sampling date, 35% more at the second sampling, 42% at the third sampling, and then steadily decreased to a 10% increase at the final sampling date. Similar to N accumulation, mean P accumulation differences between the control and the manure treatments increased to 27% at the third sampling and then gradually decreased to 14% by the final sampling date. The overall effect of variety was minimal, yet statistically significant, and interactions between manure rate and variety were not found. Applying manure for soybean increased end-of-season accumulation of DM, N, and P by 9, 10, and 14%, respectively, compared to the non-manure treatment.

Dry matter partitioning differences between shoots and roots in two contrasting genotypes of orchids and their relationship with endogenous levels of auxins, cytokinins and abscisic acid

Epiphytic orchids have been considered an interesting model for plant development and may have unusual features related to the hormonal control of shoot and root growth. In the present experiment we have studied two genotypes of Catasetum fimbriatum Lindl. (Orchidaceae) with an inverse pattern of shoot and root dry matter accumulation. Whereas the CFC1 genotype directs 60% of dry matter towards the shoot system, this same amount is directed towards the root system in the CFC4 genotype. Differences in the endogenous content of cytokinins, IAA and ABA, as well as differences in IAA conjugation and oxidation in shoots and roots were observed in the two genotypes. These differences were correlated with their dry matter partitioning patterns. Thus, the genotype that directed 60% of dry matter towards the root system showed a 20-fold higher auxin accumulation in those organs, while the one that accumulated 60% of dry matter in the shoots showed a 10-fold higher cytokinin accumulation in this plant part. Based on the well established information about auxin and cytokinin biosynthesis, conjugation, oxidation, transport, and effect on organ growth, we have presented an integrative working hypothesis to interpret the data obtained in this study. This working hypothesis may also account for the understanding of the complex relationships involving the hormonal control of the relative growth of shoots and roots in other plant models.

Jerusalem artichoke growth, development, and field storage. II. Carbon and nutrient element allocation and redistribution

Jerusalem artichokes store carbon (C) predominately in the form of inulin, a functional food of increasing interest due to its dietary health benefits for humans and calorie replacement potential in processed foods. To better understand the developmental and agronomic requirements of this crop, the allocation of C and nutrient elements into individual plant parts (stems, leaves, stolons, tubers, ‘seed’ tuber, and roots) was monitored at 2‐week intervals throughout the entire growth cycle of the cultivar ‘Sunchoke’ grown on a Cecil sandy clay loam. Accumulation patterns of C and nutrient elements in individual plant parts were generally in accordance to the pattern of dry matter accumulation, though concentration patterns differed. Overall, nutrient element levels in vegetative structures decreased with the onset of rapid tuber development. Leaves had the highest nutrient levels, except iron (Fe) and sodium (Na). The concentrations of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and copper (Cu) in tubers were greater than in stems. Total N, P, and K concentrations in the stolons were at lower levels and the total calcium (Ca), Fe, and manganese (Mn) at higher levels compared to the tubers. During rapid tuber growth, the concentration of individual phloem‐mobile nutrient elements (e.g., N, P, and K) in the leaves and stems decreased progressively due in part to reallocation. In contrast, the concentration of less mobile nutrient elements (e.g., Ca and Mn) in the leaves and stems generally increased due to losses of C and other mobile materials. In the tubers, the concentration of C and most nutrient elements remained fairly constant through the final harvest, indicating carbohydrates and nutrient elements were accumulating at the same rate. Knowledge of C and nutrient element allocation/ reallocation in the Jerusalem artichoke is of value for improving fertilization strategies and in identifying critical traits for the selection of new, high yielding cultivars.

Dynamics of Abscisic Acid Levels during Grain-Filling in Rice : Comparisons between Superior and Inferior Spikelets

In a rice panicle, the superior spikelets display higher growth rates than the inferior spikelets during the initial phase of grain-filling. To better understand the regulatory mechanism of this phenomenon, we examined the dynamics of endogenous abscisic-acid (ABA) levels and the effects of shading on the dynamics during the grain-filling period in superior and inferior spikelets. While ABA content in the superior spikelets increased rapidly after flowering, that in the inferior spikelets increased slowly and reached the maximum later than in the superior spikelets. Shading significantly exaggerated the inherently different ABA dynamics between the superior and inferior spikelets. We concluded that ABA levels are correlated with the dry matter accumulation patterns of spikelets. These results support our hypothesis that ABA is involved in assimilate partitioning among spikelets in a panicle during the initial phase of grain-filling of rice.

Dry Matter Accumulation and Dinitrogen Fixation of Annual Medicago Species

AbstractAssessment of the N2 fixation potential of annual medics (Medicago spp.) in the upper Midwest is important for predicting the net N contribution to cropping systems. Our objectives were to determine the dry matter (DM) accumulation pattern of herbage, roots, and nodules of several annual medic species used as summer annuals and to measure the percentage and amount of N derived from N2 fixation by annual medics using isotope dilution and difference methods. Experiments were conducted on a Hubbard loamy sand (Udorthentic Haploboroll) at Becker, MN, and a Tallula silt loam (Typic Hapludoll) at Rosemount, MN. The experimental design at both locations was a randomized complete block with six replicates. Medicago truncatula Gaertn., M. polymorpha L., M. scutellata (L.) Mill., and M. rugosa Desr. were inoculated with commercial rhizobial inoculant and were seeded in late May. Herbage, root, and nodule DM of N2‐fixing annual medics continued to increase until about 72 d after planting (DAP). The highest maximum herbage, root, and nodule DM yields were 10 669, 648, and 169 kg ha−1, respectively, from M. polymorpha in 1993. Based on the estimate from the isotope dilution (ID) method, herbage of annual medics at maximum DM accumulation contained 86% N derived from atmosphere (%Ndfa), using ryegrass (Lolium multiflorum Lam.) as a reference crop, or 79% Ndfa, using noninoculated M. rugosa as a reference crop. The amount of Ndfa in annual medic herbage ranged from 100 to 200 kg ha2212;1 based on estimates using either the ID method or the difference method (D‐method), with M. polymorpha producing the highest and M. rugosa producing the lowest amount. Estimates of Ndfa from the ID and D‐methods were strongly correlated. We conclude that annual medics have the potential to contribute a significant amount of N to cropping systems when seeded in the spring and harvested or incorporated into the soil 2 to 3 mo. later.

Dry matter production and partitioning of maize hybrids and dwarf unes at four plant populations

This experiment was conducted in Ames, Iowa, USA, to compare dry matter accumulation patterns of maize genotypes contrasting in height and leafiness, and to test whether reduction in plant height an leaf number through the use of dwarfing genes or earliness can improve grain dry matter allocation. Five plant genotypes were tested: a full season hybrid adapted to central lowa (NK 4525), a short season hybrid adapted to northern Minnesota (C1070), and three dwarf lines (156-A, 302-E and I17- A). The dwarves contained, respectively, the homozygous, independent, recessive dwarfing genes d3, d1 and br2. Each genotype was sown at four plant populations: 25, 50, 75 and 100.000 plants. ha-1. Hybrids had the greatest rates of decrease in total biomass and grain dry matter per plant when population was increased, though they also had larger absolute values of these variables at any given density. Hybrids produced more grain dry matter per unit of leaf area, and a higher harvest index, regardless the plant population used. Reduction in plant height or leaf number did not improve maize efficiency in producing and partitioning dry matter to the grain.

Specific distribution of gibberellins, cytokinins, indole-3-acetic acid, and abscisic acid in radish plants closely correlates with photomorphogenetic responses to blue or red light

Summary Ontogenetic patterns of dry matter accumulation and contents of cytokinins, gibberellins, indole-3-acetic acid (IAA), and abscisic acid (ABA) in shoot and hypocotyl were studied in radish (Raphanus sativus L.) plants grown under blue (BL) or red (RL) light. BL promoted the development of storage organ (swollen hypocotyl), whereas RL favoured petiole and stem growth. RL did not prevent tuber formation, but delayed tuberization, which started on days 14 and 20 in BL- and RL-grown plants, respectively, and severalfold reduced tuber weight. About 10-times higher (as compared with BL-grown plants) levels of gibberellins were found in shoots of 11-day-old RL-grown plants, and the difference between RL and BL-grown plants increased with age. The 2.5-times higher level of IAA was found in shoots of 11-day-old BL-grown plants compared with RL-grown ones. IAA levels in shoot abruptly decreased with age regardless of light quality. Compared with RL, BL increased the contents of IAA and cytokinins (zeatin plus zeatin riboside and isopentenyladenine plus isopentenyladenosine) severalfold in hypocotyls of 11- and 14-day-old plants. By day 21, IAA content in hypocotyls decreased in BL, while it increased under RL. Unlike IAA, an increase in cytokinins of hypocotyls continued by day 21, which was much more pronounced in RL-grown plants. These findings indicate that both IAA and cytokinins are involved in tuber initiation regardless of light quality, while cytokinins appear to stimulate the assimilate flow to developing storage tissue. Specific morphogenetic responses of radish plants to BL or RL seem therefore to be closely associated with the specific action of light quality on phytohormones in shoot and hypocotyl: RL enhances sink strength of aboveground organs (petioles and stem) by stimulating gibberellins, whereas BL stimulates assimilate flow to hypocotyls by an increase in IAA, cytokinins, and, probably, ABA. Mechanisms by which BL- or RL-grown plants maintain contrasting levels of different hormones in shoots and hypocotyls are discussed.

Above- and Belowground Dry Matter Accumulation Pattern Derived from Dimensional Biomass Relationships

Abstract A model of dry matter accumulation pattern is derived from above- and belowground dimensional biomass relationships as a function of basal diameter growth and total height increment. Without loss of generality, the model is illustrated utilizing previous results of analyses with eight years of growth records from precompetitive red pine (Pinus resinosa, Alt.) plantations in northern Michigan. Model behavior corresponds with previous knowledge concerning the seasonal patterns of dry matter accumulation in conifers and with the response of plant allocation patterns to temperature and moisture stress. Changes in accumulation fraction as a function of tree size also agree with previous observations. This model can be developed using existing above- and belowground dimensional biomass equations and functions describing the seasonal growth of diameter and height. The range of its applicability depends on the ranges of applicability of the component equations. Unification of this "mensurational" approach to modeling dry matter accumulation with previous functional balance methods can be achieved by placing appropriate constraints on model components. For. Sci. 42(2):236-241.

Accumulation and Partitioning of Dry Matter in Taro [ Colocasia esculenta (L.) Schott

A field study was conducted as part of an ongoing effort to collect data on patterns of leaf area development and dry matter accumulation and partitioning among various plant parts during growth and development of two taro cultivars. Plants were harvested for biomass about every 6 weeks during the growing season. At each harvest, plants were separated into various plant parts, and their dry matter content was determined. The first 80 d after planting were characterized by low rates of dry matter accumulation, with only leaves, petioles, and roots showing substantial growth. Afterwards, increases in total dry matter were mainly the result of corm and sucker growth. Corm bulking occurred after the attainment of maximal leaf area indices. The absence of an optimal leaf area index for a longer period of time may have prevented the realization of higher dry matter yields. The partitioning of dry matter to the corms of both cultivars remained almost constant especially after 150 d after planting. This process was in contrast to the partitioning of dry matter to the suckers, which increased significantly until the end of the growing cycle.

Organic Production of Angelica

Angelica (Angelica archangelica) is a tall biennial grown for its root-bound active ingredients. A research was conducted to adapt conventional angelica production methods to organic principles and nordic growing conditions. Seeds should be stratified for 7 to 8 weeks before sowing and transplant production done in multicellular trays filled with compost-peat media and supplemented with organic soluble fertilization. A sequential sampling program was conducted to better-understand the dry matter and active ingredients accumulation patterns over the growing seasons. In light of these results, the recommended production schedule consists of a fall planting and a harvest the following fall. In this manner, both dry matter yield and active ingredient concentration in the root are improved. Root yields increase linearly with planting densities up to 111,111 plants/ha. After 5 years of research, most of the limiting factors have been studied and the problems solved. Our research clearly shows how much yield, quality, and profitability of a newly introduced crop can be improved when a comprehensive research program is implemented.