Dry Weight Growth Rate Research Articles

Food waste anaerobic biogas slurry as fertilizer: Potential salinization on different soil layer and effect on rhizobacteria community

Biogas slurry(BS) from food waste anaerobic fermentation coexisted a lot of salinity that could damage soil and crops health. So, this study was to explore the effect of the application of biogas slurry on soil salinization in 1 ∼ 4 cm, 4–6 cm and 6 ∼ 8 cm soil layers every 10 days, Chinese cabbage growth and rhizobacteria. The results indicated that ≤ 10% concentration of biogas slurry was uninjurious for soil and plant, the dry weight growth rate was 73.7% compared with CK, long term application should be further evaluated the potential risk of salinity on underground water and human health. As for high concentration of biogas slurry ≥ 10% concentration of biogas slurry could inhibit the seed germination and root elongation, and the germination percentage was declined from 87.6% to 2.4%, but 50% and 100% concentration of biogas slurry showed a promotion of crop growth because of sufficient nutrition. However, the potential accumulation of salinity could be seen in high concentration of biogas slurry for long term application especially in top1-4 cm soil. Correlation analysis showed that Cl- was the main factor resulting high EC in all soil layers. 16S rRNA sequencing showed that UCG-004, Ketobacter, Sphingopyxis and RB41 could be regard as the indicators for determining the potential jeopardize on soil environmental by high salinity from biogas slurry.

Carbon dioxide enrichment promoted the growth, yield, and light‐use efficiency of lettuce in a plant factory with artificial lighting

AbstractLettuce (Latuca sativa L.) is a commercially important crop and a good candidate for production in a plant factory with artificial lighting (PFAL). To explore the influence of CO2 enrichment (eCO2) on lettuce growth, light‐use efficiency (LUE) and various aspects of the growth indicators were specifically assessed. Three CO2 concentrations ([CO2]): ambient CO2 (as the control, approximately 400 μmol mol−1), approximately double the ambient (DA‐CO2, 800 ± 50 μmol mol−1), and approximately quadruple the ambient (QA‐CO2, 1600 ± 50 μmol mol−1) were applied for 30 d. The results indicated that plant height, stem diameter, number of leaves, root length, leaf width, and maximum leaf area were all positively related to [CO2], which illustrated that growth was greater in the treatments with eCO2 than under ambient CO2. The daily average assimilation rate (DAAR), the average dry weight growth rate (GRdw), and yield were also greater for plants grown under DA‐CO2 and QA‐CO2 than under ambient CO2 (DAAR increased by 25.45% and 42.27%, GRdw increased by 28.76 and 37.55%, and yield increased by 33.65 and 44.16%, respectively). Light‐use efficiency increased by 28.51 and 41.12% for DA‐CO2 and QA‐CO2 compared with ambient CO2, respectively. We concluded that eCO2 has the potential to enhance production as well as light utilization in PFAL.

Recovery of terrestrial plants in vegetative vigor and seedling emergence tests from exposure to atrazine.

Ten species of terrestrial plants, including 6 dicotyledonous and 4 monocotyledonous species, were exposed to a direct overspray of atrazine according to US Environmental Protection Agency seedling emergence and vegetative vigor study guidelines and subsequently evaluated for potential recovery. For each species, no-observed-effect rate (NOER), 10% effect rate, 25% effect rate, and 50% effect rate values were calculated (where possible) for a variety of guideline-required endpoints (but focusing on growth rate) for both the standard experimental phase and a recovery phase; and the rates subsequently were compared. For the seedling emergence study, the standard experimental (designated test 1) and recovery (designated test 2) phases encompassed days 0 to 14 and days 14 to 28, respectively. Similarly, for the vegetative vigor study, test 1 and test 2 encompassed days 0 to 21 and days 21 to 42, respectively. Plants were exposed to atrazine at nominal application rates ranging from 1.1 g active ingredient (a.i.)/ha (0.0010 lb a.i./A) to 28,000 g a.i./ha (25 lb a.i./A), depending on the species; the 28,000 g a.i./ha rate is greater than 12 times the maximum application rate of 2250 g a.i./ha (2 lb a.i./A) registered on corn. For seedling emergence, only 2 of 10 species tested, cabbage and tomato, provided clear rate responses in the initial 14 d of exposure (test 1). Based on a comparison of x% effect rate (ERx) and NOER values for growth rates of shoot length and shoot dry weight for days 0 to 14 relative to days 14 to 28, recovery was apparent for cabbage shoot length growth rate and tomato shoot length and shoot dry weight growth rates. Test application rates selected for the remaining 8 species showed either a weak response that did not allow a clear assessment of recovery or no response at all. For the vegetative vigor study, 9 of the 10 species tested provided clear rate responses in test 1 (days 0-21); corn did not demonstrate any herbicidal response up to the highest rate tested, 28,000 g a.i./ha. Based on comparison of day 0 to 21 (test 1) relative to day 21 to 42 (test 2) ERx and NOER values for shoot length, average growth rates indicated that 8 of 9 species clearly demonstrated an increase in 2 or more metrics (cabbage did not demonstrate a response based on shoot length). Clear recovery was also indicated by an increase in ERx and/or NOER values from test 1 to test 2 for shoot dry weight average growth rates for 7 of the 9 species (corn did not show a response, and oat and soybean showed variable responses). Thus, in most species, where initial herbicidal effects were observed, the effects are largely ameliorated over time.

Microalgal growth with intracellular phosphorus for achieving high biomass growth rate and high lipid/triacylglycerol content simultaneously

Nutrient deprivation is a commonly-used trigger for microalgal lipid accumulation, but its adverse impact on microalgal growth seems to be inevitable. In this study, Scenedesmus sp. LX1 was found to show similar physiological and biochemical variation under oligotrophic and eutrophic conditions during growth with intracellular phosphorus. Under both conditions microalgal chlorophyll content and photosynthesis activity was stable during this growth process, leading to significant increase of single cell weight and size. Therefore, while algal density growth rate dropped significantly to below 1.0×105cellsmL−1d−1 under oligotrophic condition, the biomass dry weight growth rate still maintained about 40mgL−1d−1. Meanwhile, the lipid content in biomass and triacylglycerols (TAGs) content in lipids increased significantly to about 35% and 65%, respectively. Thus, high biomass growth rate and high lipid/TAG content were achieved simultaneously at the late growth phase with intracellular phosphorus. Besides, microalgal biomass produced was rich in carbohydrate with low protein content.

Ontogeny of swimming capacity in plaice (Pleuronectes platessa) larvae

Little is known regarding the swimming ability of the larvae of European plaice (Pleuronectes platessa) in relation to changes in total length (TL), dry weight (DW) and developmental stage, which is surprising given the importance of transport processes to the recruitment dynamics of this species in the North Sea and elsewhere. We investigated ontogenetic changes in the critical swimming speed (Ucrit) of plaice from hatching to the onset of metamorphosis (50 days post-hatch, dph) at 8 °C. The mean (±SD) TL and DW growth rates were 1.59 ± 0.81 and 7.7 ± 0.35 % d−1, respectively. Larvae were unable to swim at against a minimum current speed of <0.5 cm s−1 until 10 dph (7 mm TL), after which Ucrit significantly increased with increasing TL until the onset of metamorphosis and subsequent settlement. Mean (±SD) Ucrit was 0.38(0.35), 1.59(0.54), 2.27(0.49) and 2.99(0.37) cm s−1 for stage I (6.61 ± 2.64 mm TL), stage II (7.75 ± 0.60 mm TL), stage III (9.10 ± 1.00 mm TL) and stage IV (11.59 ± 0.85 mm TL) larvae, respectively. Larval TL, DW, DNA content, RNA content and Ucrit significantly increased, whereas sRD significantly declined as larvae developed from stage I to V. Although inter-individual differences in Ucrit (coefficient of variation, CV = 33 %) were as large as those in biochemical and morphological condition (CV’s of 21–42 %), differences in Ucrit were not significantly related to those in nutritional condition and larvae with lower DNA/DW had also better swimming abilities. These estimates should be useful to ongoing efforts to create individual-based models of the transport, foraging and growth of plaice larvae in the North Sea.

Ontogenetic patterns of growth and lipid composition changes of blue swimmer crab larvae: insights into larval biology and lipid nutrition

Blue swimmer crab, Portunus pelagicus, is a commercially important crab throughout the Indo-Pacific region, that plays an important role in the food chains of coastal ecosystems. P. pelagicus undergoes four pelagic zoeal stages and a post-larval megalopal stage before settling as benthic juvenile; however, very limited information is available on larval biology and lipid nutrition of this species. The present comprehensive study investigated survival, growth and ontogenetic changes in lipid composition of P. pelagicus larvae under laboratory conditions. Larvae were fed rotifers (zoea I), rotifers and Artemia (zoea II) and enriched Artemia (zoea III – megalopa), consecutively. Among five larval stages of P. pelagicus, zoea I and II had the shortest durations (2.2–2.3 days), whereas megalopa had the longest duration (4.7 days). As larvae developed, their wet weight, dry weight and carapace length increased exponentially. Lower mortality occurred during zoea II (12.5%) and zoea III (14.3%), coincidental with the lower percentage increments in dry weight and specific growth rate of dry weight during these two stages. Generally, fatty acid composition of larvae can reflect that of their diets. However, increases in mono-unsaturated fatty acids, 20 : 4n-6 and 22 : 6n-3 in megalopa and the first crab compared with zoea IV might suggest that the later larvae were still deficient in essential fatty acids, and that 20 : 4n-6 and 22 : 6n-3 were preferentially accumulated. Therefore, measures of ontogenetic patterns of growth and lipid composition will provide valuable insights for better understanding of larval biology and lipid nutrition of P. pelagicus.

Differential proteomic analysis of soluble extracellular proteins reveals the cysteine protease and cystatin involved in suspension-cultured cell proliferation in rice

Extracellular matrix proteins play crucial roles in plant development, morphogenesis, cell division, and proliferation. To identify extracellular proteins that regulate cell growth, the soluble proteins of extracellular matrix were extracted from suspension-cultured rice cells for different lengths of time. The extract obtained from 3-d cultures was found to increase cells' fresh weight, while extracts from 6-d and 9-d cultures showed no effect on cells' growth. A comparative proteomic analysis was used to identify soluble extracellular proteins differentially expressed between 3 and 6 days in suspension-cultured cells. Ten unique protein spots were isolated and identified by mass spectrometry. Among them, included a cysteine protease (OsCP) and a putative cysteine protease inhibitor (cystatin, OC-I). OsCP has been down regulated in vivo using RNAi transgenic lines. The fresh and dry weight growth rates of OsCP RNAi cell lines were lower than empty vector control. Recombinant protein of OC-I could inhibit the OsCP protease activity, also it could inhibit the weight increase of suspension-culture cell as well as extracellular protease activity. These results suggest that OsCP and OC-I may be involved in the process of suspension-cultured rice cells proliferation.

Annual Production of &lt;i&gt;Bellamya aeruginosa&lt;/i&gt; in Houhu Lake, Wuhan

1996-1997年对后湖铜锈环棱螺进行了周年研究,结果表明其种群含三个年龄组,其中1996年组生长最快,其去壳干重瞬时生长率为2.80.采用瞬时生长率法测算其周年生产量为:带壳湿重33.13g m^-2a^-1;去壳千重1.932g m^-2a^-1;P/B系数为0.85.;An investigation on one of the dominant species of gastropods, Bellamya aeruginosa in Houhu Lake, Wuhan was carried out from April, 1996 to March, 1997.The results showed that the population was composed of three year classes, among which the 96 year class grew most quickly, with instantaneous growth rate of dry weight (unshelled) 2.80.The annual production of the animal calculated by instantaneous growth rate method was: wet weight, 33.13 g m^-2a^-1;dry weight (unshelled), 1.932 g m^-2a^-1.The corresponding annual P/B ratios was 0.85.

Variation in Larval Growth Rate among Striped Bass Stocks from Different Latitudes

Field observations of a variety of fish species at different latitudes suggest that there is an inverse (countergradient) relationship between growth rate within the first growing season and the length of the growing season. In this study, larvae of striped bass Morone saxatilis from four different latitudes—Hudson River, New York (NY) (41°N); Nanticoke and Patuxent rivers, Maryland (MD) (38°N); Santee–Cooper river system, South Carolina (SC) (33°N); Apalachicola River, Florida (FL) (30°N)—were raised in captivity under identical conditions to determine if differences in growth could be detected among the populations. Larvae from two mothers per latitude were reared at two temperatures (17°C and 21°C) with replication. The general result was that MD and NY larvae exhibited the highest growth rates and SC larvae grew the slowest. At 17°C, a significant difference in standard length growth rate was detected between MD larvae, the fastest growing population, and SC larvae, the slowest growing population. At 21°C, the rank order for growth in standard length was MD = NY > FL = SC. No significant differences in dry weight growth were found at 17°C. At 21°C, a significant difference in dry weight growth rate was detected between NY larvae—the fastest growing population—and SC larvae—the slowest growing population. Significant differences among the populations also were found in egg weight and egg oil volume. However, these maternal effects did not exert a statistically significant influence on growth rate. Results indicate the existence of a countergradient relationship between larval growth rate and the length of the growing season among striped bass from different latitudes.

Analysis of translocatory balance in durian (Durio zibethinus) fruit

We estimated translocatory balance in fruit of the tropical tree Durio zibethinus Murray on the basis of a compartment model. Rates of fruit respiration, dry weight growth and translocation increased with time. Over the 8.2 weeks of fruit development, the relative distribution of translocation was 80% to dry weight growth and 20% to respiration. The ratio of respiration rate to translocation rate, which ranged from 14 to 32%, tended to decrease with time, whereas the ratio of dry weight growth rate to translocation rate, which ranged from 68 to 86%, tended to increase with time. The relationship between dry weight growth rate and translocation rate was fitted by a power function, where dry weight growth rate was statistically proportional to translocation rate. The relationship between respiration rate and translocation rate was formulated by a smooth curve, where respiration rate increased as translocation rate increased. Examination of these ratios with respect to the translocation rate indicated that the dry weight growth rate/translocation rate ratio increased slightly with increasing translocation rate, whereas the respiration rate/translocation rate ratio decreased with increasing translocation rate. A comparative analysis of these results with those obtained for Cinnamomum camphora (L.) J. Presl revealed a lower ratio of translocation to dry weight growth in D. zibethinus than in C. camphora, indicating that D. zibethinus fruits have a low translocatory efficiency.

Papaya Fruit Growth, Calcium Uptake, and Fruit Ripening

The uptake of Ca by `Sunset' papaya (Carica papaya L.) fruit and its role in ripening was studied. The highest mesocarp Ca uptake rate occurred in fruit that were &lt;40 days postanthesis when fruit transpiration was probably highest. Ca uptake rate by the mesocarp was low, from 60 to 80 days postanthesis when fruit fresh and dry weight increased. Mesocarp Ca uptake rate increased again from 100 to 140 days postanthesis when fruit fresh weight growth rate declined and dry weight growth rate increased. Mesocarp Ca concentration did not significantly differ from the peduncle to the blossom end. although Ca was significantly higher in the outer than inner mesocarp at the fruit equator. Mesocarp Ca concentration fluctuated significantly throughout the year ranging from 68 to 204 μg·g-1 fresh weight (FW). Soil Ca application did not always increase fruit mesocarp Ca concentration, while K and N fertilization decreased mesocarp Ca concentration. Attempts to increase mesocarp Ca concentration by spraying CaCl2 onto papaya fruit during growth and by postharvest vacuum infiltration and dipping of the cut peduncle into CaCl2 were unsuccessful. Mesocarp Ca concentration was positively correlated to the firmness of ripe papaya fruit and the rate of softening of mesocarp plugs. Less correlation was found between fruit firmness and the ratio of Ca concentration to K or Mg concentration, or to Mg plus K concentrations. Mesocarp Ca concentration of 130 μg·g-1 FW or above was associated with slower fruit softening rate than fruit with a lower concentration.

Development of the Fifth Leaf is Indicative for Whole Plant Performance at Low Temperature in Tomato

In the search for early-detectable selection criteria for growth at low temperature conditions in tomato, first the initiation and growth of individual leaves was analysed. Scanning electron microscopy revealed that the first four primordia had already developed during the germination period at 25°C. The primordium of the fifth leaf, however, was initiated after the transfer of seedlings to the experimental conditions. The increase in length of the first three leaves, and to a lesser extent of the fourth leaf, was considerably smaller in comparison with that of later formed leaves. Moreover, the morphology of the first three to four leaves was deviant, whereas the others showed the normal compound leaf architecture. All these results indicated that the fifth leaf was the earliest formed leaf with growth characteristics that might reflect the growth potential of the whole plant.Development of the fifth leaf was tested as a marker for whole plant growth. At three temperature, 18, 15 and 12°C, growth responses of the fifth leaf were similar to that of whole plants in four tomato genotypes: Line A, Line B, Premier and MXXIV-13. Significant differences in relative growth rate of dry weight of whole plants and fifth leaves (RGRW)and of leaf area of the fifth leaves (RGRLA between two fast growing and two slow growing genotypes were found. No genotype by temperature interaction for RGRW and RGRLA was found, indicating that the effect of temperature decrease was similar for the four genotypes.The structure of the mature fifth leaf of one fast and one slow growing genotype, Line A and MXXIV-13, was analysed. For both genotypes, leaves were small and thick at low temperature, 12°C. The total number of epidermis and palisade parenchyma cells per leaf was smaller but the size of the cells developed at 12°C was larger than at 18°C. Consequently, the slow growth at 12°C was due to a low rate of cell division. At both temperatures, the fifth leaf to MXXIV-13 was smaller compared to that of line A. Since the size of the cells were similar, the smaller leaf size was due to lower number of leaf cells.The results confirm the suitability of the growth, especially expressed as RGRLA , of the fifth leaf as a nondestructive market for vegetative development of tomato at low temperature. Growth differences between genotypes were mainly reflected by differences in cell number of leaves, which might be correlated with genetically determined differences in cell number of leaf primordia.

Effects of microsite light availability on the survival and growth of oak seedlings within a grassland

Effects of microsite light availability on the growth and survival of transplantedQuercus serrata Thunb. seedlings in aMiscanthus sinensis Anderss. grass canopy were investigated by a “plant's eye view” approach. Diffuse site factors, i.e., the fractional transmissions of diffuse photosynthetic photon flux density, were estimated at 15 cm aboveground in 108 microsites where the seedlings grew. Microsite diffuse site factors were significantly different between surviving and dead seedlings during the experiment period from April to October (F[1,14]=10.9, P<0.01). Relative growth rate of dry weight for individual seedlings positively depended on the diffuse site factors (r2=0.482, P<0.001 in May; r2=0.312, P<0.001 in October). Only 16 seedlings produced their second stem flush within the grass canopy. The ratio of height to dry weight of the second stem flush was significantly higher for the seedlings grew in shady microsites than for those in less shady microsites (r2=0,471, P<0.01 in May). This study suggests that the microsite heterogeneity of light availability is one of the important factors affecting the establishment of tree seedlings in patchy grasslands.

Nutritional value of spray-dried Tetraselmis suecica for juvenile bivalves

Juvenile bivalves of five commercially important species ( Tapes philippinarum, T. decussata, Mercenaria mercenaria, Crassostrea gigas and Ostrea edulis) were fed a spray-dried preparation of Tetraselmis suecica. Growth and carbohydrate content of the juveniles were measured and compared with animals fed live T. suecica, a live diatom ( Chaetoceros calcitrans), or a mixture of these two algae. Dry weight growth rate and carbohydrate content were similar for juveniles fed dried or live T. suecica. Growth rate was less and carbohydrate content greater than those for animals fed C. calcitrans or the mixed live diet. Food cell consumption rates of the various diets were compared. In most cases, the weight of each diet eaten was similar for each bivalve species. Preliminary observations on the effect of supplementing the dried diet with live algae show that a mixture containing 20% C. calcitrans gave improved growth.

Growth and biomass partitioning in zinc‐toxic bush beans

Abstract Bush bean plants (Phaseolus vulgaris L.) were grown during the exponential growth phase in nutrient solution containing 2, 6.6, 9.6 or 13.5 μM Zn. At six different harvest intervals samples were taken for dry weight and Zn content determinations. The primary growth data were fitted to exponential curves, from which the relative growth rates (RGR) and the net assimilation rates (NAR) were derived. With the RGR data the biomass partitioning coefficients of the different organs were calculated. Zinc toxicity generally decreased both the NAR and the growth of all organs, and increased their Zn contents. The relative root expansion rates (RER) and the relative root dry weight growth rates were the most affected parameters, while the leaf expansion rates and the stem dry weight growth rates were hardly affected. The biomass partitioning coefficients indicate that after long‐term exposure to toxic Zn levels the root growth is more affected than the photosynthetate production. This leads to a relative in...

The use of artificial diets in rearing bivalve spat

Spat of five species of commercially cultivated bivalve molluscs were reared in 50-l recirculating sea water systems. They were held in one of three feeding regimes: a live algal diet, a microencapsulated artificial diet, and not fed. Dry weight growth rates of oyster and clam spat fed the artificial diet were up to 54% and 64%, respectively, of the rates with the algal diet. Unfed spat showed almost no growth. Substitution of the microencapsulated diet with 40% and 15% by weight of algae for oysters and clams, respectively, gave growth similar to that with the algal control diet.

クロガシラガレイ稚子魚の成長に伴うたんぱく質量と核酸量の変化

Protein, DNA and RNA contents, together with the growth rates of body length and dry weight were measured for the cresthead flounder Limanda schrenki, during one month after hatching. The larvae showed no remarkable changes of external morphology in the first two weeks, started metamorphosis in the third week, and then into benthic phase in the fourth week. The maximum value of growth rates of body length and dry weight were observed in the second week. The changes in increasing rate of the protein showed the same tendency as that of dry weight. The values of protein increasing rate in the first week was almost equal to the growth rate of dry weight, while in the second week the former was lower than the latter. This result may be caused by the fact that some nonprotein materials accumulated in the second week. The pattern of changes in DNA content tended to be similar to changes in RNA content. The increasing rates of DNA and RNA were highest in the second week, and minimum rates were seen in the third week. Protein/DNA ratio indicated cell size, decreased rapidly during the first two weeks, whereas only in the third week did the ratio increase. The result indicated that cell proliferation occurred actively in the first two weeks and cell enlargement was taking place primarily in the third week. In the fourth week, there is less significant difference among the increasing rate of dry weight, protein, DNA and RNA.

Studies on the growth and productivity of maize for whole-plant silage in the north-marginal area, Nemuro district in Hokkaido.

The object of this report is to clarify the dry-matter accumulation habits during the early vegetative growth period and to investigate the effect of the early growth on yield and quality of maize for whole-plant silage in the north-marginal area in Japan (where accumulated temperature from May to September is 2200°C.). Experiments were conducted for 6 years (1978∼'83), based on the same design. Wase-homare (an eary hybrid) was planted on three dates from mid-May to early-June in 1978∼'82 and late-May in 1983. The dry-matter weight in each organ was measured at the 4th-, 7th-, and 11th-leaf fully developed stages, and dry-matter yields were measured at harvesting date. The results obtained were as follows : 1. Root dry weight growth rate in each growth period from emergence to the 11th-leaf stage showed highly positive correlations with leaf expansion rate and top growth rate (TGR)(Table 1). 2. TGR during the period from emergence to the 4th-leaf stage showed highly positive correlations with daily maximum temperature and sunshine hours, but was not correlated with solar radiation (Table 2). 3. TGR in each growth period from emergence to the 7th-leaf stage showed a highly positive correlation with LAI. TGR during the period from the 7th-leaf stage to the 11th-leaf stage showed highly positive correlations with both of LAI and NAR (Table 3). 4. TGR during the period from emergence to the 4th-leaf stage showed highly positive correlations with ear DM yield, total DM yield and percentage of dry-matter in whole-crop, but was not correlated with stover DM yield (Fig. 4). 5. Thus it was concluded that the early growth is of great significance on the growth and development of ears which are essential for stable and high yield, and high quality of maize for whole-plant silage under severe conditions in the north-marginal area.

Studies on the Growth and Productivity of Maize for Whole-Plant Silage in the North-Marginal Area, Nemuro District in Hokkaido : II. Dry-matter accumulation habits and climatic factors.

The object of this report is to clarify the dry-matter accumulation habits and to investigate the effects of climatic factors on the dry-matter production and yield of maize for whole-plant silage in the north-marginal area in Japan. Experiments were repeated in the same method except variety and planting date over 6 years (1976∼'81). Heigen-wase (early hybrid) was used over a 3-year period (1976∼'78), and Wase-homare(early hybrid) was used over a 4-year period (1978∼'81). Both varieties were planted on 4 or 3 different dates from mid-May in each year. The dry-matter weight in each organ was measured at 3-week intervals, from 6 weeks before silking date, and dry-matter yields were measured at harvesting date. The results obtained were as follows: 1. The dry weight of leaf blade showed little variation during the ear-filling period. The dry weight of stem (culm+leaf sheath+tassel) increased slowly during the first half of the ear-filling period and then showed increase or decrease during the latter half of the ear-filling period. The dry weight of ear )kernel+cov+husk) increased linearly, and showed extremely large differences among years. The dry weight of top was affected remarkably by the weight of ear, which resulted in large differences among years in the dry weight of top (Fig. 2 and Fig. 3). 2. Top dry weight growth rate (CGR) changed like a shape of unimodal curve with a peak value occurring at about silking in each year, and showed a rapid decrease during the ear-filling period. Net assimilation rate(NAR) showed a tendency to have a maximum value during the period of 3 weeks before silking. Leaf area index (LAI) reached a maximum at silking or 3 weeks after silking and then decreased gradually (Fig. 4). 3. CGR in each growth period indicated highly positive correlation with different growth parameters: with LAI during the period of 6∼3 weeks before silking, with NAR during the period of 3 weeks before silking (period II) and the first half of the ear-filling period (period III), and with both of NAR and LAI during the latter half of the ear-filling period (period IV), respectively (Table 1). 4. CGR in the period II positively correlated with temperature of daily mean, maximum and minimum, and sunshine hours, but negatively correlated with rainfall. CGR in the period III and IV indicated highly positive correlation with the three temperature factors described above, sunshine hours and solar radiation, and indicated the highest positive correlation with daily maximum temperature. But CGR in the period IV indicated negative correlation with daily mean wind speed (Table 2). 5. Stover DM yield indicated positive correlation with CGR in the period II. Ear DM yield indicated highly positive correlation with CGR in the period III and IV. Although total DM yield was affected by the ear ratio, total DM yield indicated the highest positive correlation with CGR in the period III and IV. Both of percentages of dry-matter in ear and whole-plant, and ear/total ratio indicated highly positive correlation with CGR in later growth period. CGR during the latter half of the ear-filling period showed the greatest influence on yield and quality of maize for whole-plant silage (Table 4). 6. From above results, it was concluded that increase of CGR during the latter half of the ear-filling period was essential for stable and high yield and quality of maize for whole-plant silage under severe conditions in the north-marginal area.

Relative abundance and growth of mussels (Mollusca: Eulamellibranchia) in pools 8,9 and 10 of the Mississippi River

SUMMARY. Twenty‐three species of unionid mussels were sampled during the summer of 1975 from a 76‐mile reach of the Upper Mississippi River; this represented eight species fewer than were recorded in a 1930–31 survey for the same section of the river. Of the 244 sites sampled in 1975, mussels were found at 116 sites and the ten most productive sites accounted for 40.8% of the 1205 mussels collected. There were as many as thirteen different mussel species taken from one sampling site. The two most abundant species (Amblema peruviana and Megalonaias gigantea) constituted 54.5% of the mussels sampled in 1975; these two species made up only 8.3% of the 1930–31 survey. Individuals of the twelve most abundant mussel species were aged, and shell‐length growth equations were determined. In addition, shell‐free dry weight growth rate and shell weight growth rate was determined for Amblema peruviana. The calculated annual production for A. peruviana (assuming a mean density of 1 per m2) was 482 mg/m2 shell‐free dry weight, and 14.471 g/m2 shell weight.