Top Fresh Weight Research Articles

TAGETES PATULA SEEDLING PRODUCTION

The objective of this project was to propose an alternative for ecological destination of residues discarded in the environment. The selected residue was carbonized rice coat mixed with sand in different proportions in order to obtain substrates with 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 g.cm -3 densities. The substrates were tested in an experiment with Tagetes patula seedlings, and the experimental layout adopted was a complete randomized design with 8 treatments, 6 replications and 30 plants per parcel. At the end of the experiment, the phytotechnical parameters and substrate physical characteristics were evaluated. The data obtained were analyzed through the SAEG software and the analyses performed were analysis of variance and Tukey test. When different densities of substrates were evaluated in Tagetes seedlings cultivation it was observed that the 0.2 and 0.3 g.cm -3 densities presented the best results in most of the evaluated variables. Regarding the phytotechnical characteristics, the experiment presented results that are significantly better for height of seedlings, fresh top weight, dry top weight and root weight and roots volume. As for the physical characteristics, the substrates presented total porosity, space occupied by air, available water and easily available water with adequate levels for substrates. When analyzed as a whole, the data obtained in the phytotechnical and physical characteristics showed that the air volume was the limiting factor for the seedlings development.

Pathogenicity and host‐parasite relationships of the root‐knot nematode Meloidogyne incognita on celery

Pathogenicity and host‐parasite relationships in root‐knot disease of celery (Apium graveolens ) caused by Meloidogyne incognita race 1 were studied under glasshouse conditions. Naturally and artificially infected celery cv. D’elne plants showed severe yellowing and stunting, with heavily deformed and damaged root systems. Nematode‐induced mature galls were spherical and/or ellipsoidal and commonly contained more than one female, males and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. The cytoplasm of giant cells was aggregated along their thickened cell walls and consequently the vascular tissues within galls appeared disrupted and disorganized. The relationship between initial nematode population density (Pi) and growth of celery plants was tested in glasshouse experiments with inoculum levels that varied from 0 to 512 eggs and second‐stage juveniles (J2) mL−1 soil. Seinhorst's model y = m + (1 – m)zP–T was fitted to height and top fresh weight data of the inoculated and control plants. The tolerance limit with respect to plant height and fresh top weight of celery to M. incognita race 1 was estimated as 0·15 eggs and J2 mL−1 soil. The minimum relative values (m) for plant height and top fresh weight were 0·37 and 0·35, respectively, at Pi ≥ 16 eggs and J2 mL−1 soil. The maximum nematode reproduction rate (Pf/Pi) was 407·6 at an initial population density (Pi) of 4 eggs and J2 mL−1 soil.

Pathogenicity and Host-Parasite Relationships of Meloidogyne arenaria in Sweet Basil.

Stunted growth of sweet basil (cv. Genovese) associated with large patches and severe soil infestations by the root-knot nematode Meloidogyne arenaria race 2 were observed in open fields at the end of the crop-growing season in Albenga, province of Savona, Northern Italy by early September 2007. Observed morphological traits of nematode life stages and results of analysis of isozyme electrophoretic patterns and differential host tests were used for nematode species and race identification. Nematode-induced mature galls (either in naturally infected plants or in artificially inoculated root tissues) were spherical or ellipsoidal and confluent along the root axis, containing usually several females, males, and egg-masses with eggs. Feeding sites were characterized by the development of giant cells that contained several hypertrophied nuclei and nucleoli. Giant cell cytoplasm was aggregated along the thickened cell walls. Vascular elements within galls appeared disorganized and disrupted. Due to the heavy damage observed, the relationships between the initial population density and growth of basil plants was also tested in a greenhouse experiment in which inoculum levels varied from 0 to 512 eggs and juveniles/cm3 of soil. Height and top fresh weight data of the inoculated and control plants was fitted to Seinhorst's model. Tolerance limits with respect to plant height and fresh top weight of basil cv. Genovese plants to M. arenaria race 2 were estimated as 0.15 eggs and juveniles/cm3 of soil. The minimum relative values (m) for plant height and top fresh weight were 0.39 and 0.19 at initial nematode population density (Pi) ≥16 eggs and juveniles/cm3 of soil, respectively. The maximum nematode reproduction rate (Pf/Pi) was 448.7 times at an initial population density of 4 eggs and second-stage juveniles/cm3 of soil.

Effects of plastic mulches on root zone temperature and on the manifestation of tomato spotted wilt symptoms and yield of tomato

Tomato spotted wilt (TSW) disease is a serious constraint to tomato production in various regions of the world. The effect of TSW on tomato yield is largely influenced by time of infection. Early infection usually results in severe stunting of the seedling and even death of the plant. Plastic film mulches affect both the incidence of TSW, and plant growth and yield of tomato. The objective of the present study was to determine the effect of root zone temperature (RZT) as affected by plastic film mulch on the manifestation of symptoms of TSW, and growth and yield of tomato plants either artificially inoculated with tomato spotted wilt virus (TSWV) or under natural TSW infection. In artificially inoculated plants as well as in plants under natural TSW infection, vegetative top fresh weight (FW) and fruit FW both increased with the length of time after transplanting that the plants remained free from TSW symptoms. The root zone temperature was highest under black mulch (seasonal mean = 27.5 °C), followed by gray (27.0 °C), silver (25.8 °C), and white (24.8 °C) mulches. The plants grown on black mulch showed the earliest appearance of TSW symptoms, and had significantly reduced vegetative growth and fruit yields compared to plants on the other mulches. In conclusion, utilization of plastic mulches that created conditions of high RZT stress resulted in reduced plant growth and yield and predisposed the plants to earlier expression of TSW symptoms compared to plants grown at RZTs more favorable to tomato plant growth (optimal RZT = 26.1 °C [Díaz-Pérez, J.C., Batal, K.D., Granberry, D., Bertrand, D., Giddings, D., Pappu, H., 2003. Vegetative top growth and yield of tomato grown on plastic film mulches as affected by the appearance of symptoms of Tomato spotted wilt virus. HortScience 38, 395–399]). Since these plant responses to TSW under heat stress occurred in artificially inoculated plants as well as in plants under natural TSW infection, high RZTs probably affected the plants directly, independently of any possible effects on the thrips vectors.

Growth Promotion for Seedling of Vegetable Plants with Supplemental Lighting

A supplemental lighting system was installed at a large-scale seedling greenhouse (12.5 m×45 m), which supplies high quality and large quantity of seedlings to farmers through out the year. A test experiment of supplemental lighting for seedlings in this house was performed during the rainy season and winter-early spring to prepare for planting, when sunshine is sometimes insufficient. A mercury-free high pressure sodium lamp of 400W with a red to far-red photon flux (R/FR PF) ratio of 1.1 was developed and manufactured for this experiment. The average PPFD was 100μmol m-2 s-1. The experimental plants were lettuce, broccoli, and cabbage. In both rainy and winter-early spring experiments, we found that supplemental lighting was effective for seedling growth. Significant supplemental lighting effects in the rainy season were found for broccoli. Top fresh weights of both a 2h lit area before sunrise and after sunset were 30-60% greater than those of the non-lit area. A drop test of lettuce demonstrated that the remaining ratio of soil of both a 2h lit area before sunrise and after sunset were about 87%, and those of the non-lit areas were about 78%. Thus, good growth in roots was found. A significant supplemental lighting effect in winter-early spring was found in the lettuce experiment. Top fresh weights of both a 3h lit area before sunrise and after sunset were 165-200% greater than those of the non-lit area. In winter-early spring experiments, a clear difference between a 3h lit area before sunrise and after sunset was not found.

Root Zone Temperature as Modified by Plastic Mulches Affect the Appearance of First Systemic Symptoms of Tomato Spotted Wilt and Fruit Yield in Tomato

Tomato spotted wilt (TSW) is a serious constraint to tomato production in various regions of the world. The effect of TSW on tomato yield is largely influenced by time of infection. Early infection usually results in severe stunting of the seedling and even death of the plant. Plastic mulches have been found to affect both the incidence of TSW, and plant growth and yield of tomato. The objective of this study was to determine the effect of root zone temperature (RZT) as affected by plastic mulch on the timing of appearance of first TSW symptoms, vegetative top fresh weight (FW) and fruit FW in tomato. Under natural TSW infection as well as in artificially inoculated plants, vegetative top FW and fruit FW were both linearly related with number of days after transplanting (DAT) the plants were free from TSW symptoms. The plants grown on black mulch during the fall showed earlier appearance of TSW symptoms, and had significantly reduced vegetative growth and fruit yields. The mean RZT during the first 42 DAT—the time before the plants reached full canopy closure—significantly affected the timing of first appearance of TSW symptoms, tomato plant growth and fruit yield. Vegetative top FW (optimal RZT = 24.1 °C) and fruit FW (26.9 °C) fitted the quadratic relationships with the mean RZT during the first 42 DAT. In conclusion, utilization of plastic mulches that created conditions of RZT stress, particularly heat stress, resulted in reduced plant growth and yield and may predispose the plants to earlier expression of TSW symptoms compared to plants grown under RZTs more favorable to tomato plant growth.

Influence of the root-knot nematode Meloidogyne incognita r. 1 on growth of grapevine

Abstract The effect of Meloidogyne incognita race 1 at different population densities (0, 0.0625, 0.125, 0.25,... 256 eggs and juveniles/cm3 soil) on the growth of a rootstock (1103 Paulsen) and a cv. Italia of grapevine was studied in glasshouse experiment. One-year-old, self-rooted plants were transplanted into 1,200 cm3 plastic pots containing soil infested by M. incognita race 1 at different inoculum levels. Reproduction of M. incognita race 1 was significantly higher on cv. Italia than on the rootstock 1103 Paulsen. Tolerance limits (T) of 1.28 and 0.78 eggs and juveniles/cm3 soil were estimated respectively for 1103 Paulsen and Italia. Minimum relative plant growth of 0.55, 0.80 and 0.85, respectively for shoot length and node number increase and fresh top weight, were estimated for 1103 Paulsen; whereas values of 0.25, 0.50 and 0.60 were assessed for the cv. Italia. Nematode equilibrium density was 33.6 and 137.8 eggs and juveniles/cm3 soil, on 1103 Paulsen and Italia, respectively.

Effects of Nocturnal Soil Temperatures and Meloidogyne incognita Densities on Cotton Seedling Growth and the Interaction with Thielaviopsis basicola

Controlled studies were conducted to evaluate the effects of soil temperatures typical of field conditions during the first 6 weeks of the growing season in Arkansas and different population densities of Meloidogyne incognita on damage to cotton (Gossypium hirsutum) seedlings associated with the interaction between M. incognita and Thielaviopsis basicola. Treatments consisted of varying nocturnal temperatures that approximated the temperatures that occurred during the 2001, 2002, and 2003 growing seasons in southeastern Arkansas. Nocturnal temperatures in the study were as follows: high, the first week at 15°C, followed by 3 weeks at 17°C, 1 week at 21°C, and 1 week at 17°C (approximating the 2002 season); medium, 3 weeks at 15°C and 3 weeks at 19°C (approximating the 2003 season); and low, 1 week at 15°C, 1 week at 13°C, 2 weeks at 17°C, 1 week at 15°C, and 1 week at 17°C (approximating the 2001 season). Pathogen population densities were either 0 or 100 chlamydospores of T. basicola per gram of soil and 0, 2,000, 4,000, or 8,000 eggs of M. incognita per 500 cm3of soil. Plant height and fresh top weight increased with an increase in nocturnal temperature across treatments. There were significant reductions in plant growth and development with T. basicola, but not with M. incognita, at these nocturnal temperatures, but decreased plant height and weight were seen where both pathogens were present in comparison with either pathogen alone. Trends of increased disease associated with T. basicola were observed with increasing inoculum rates of M. incognita, indicating that the interaction between T. basicola and M. incognita occurs even at soil temperatures below the minimum temperature reported as necessary for damage from M. incognita.

Root Zone Temperature, Plant Growth, and Fruit Yield of Tomatillo as Affected by Plastic Film Mulch

Tomatillo (Physalis ixocarpa Brot. ex Hornem) is a popular crop in Mexico and other Latin American countries. There is an increasing demand for this vegetable in the United States, particularly from the growing Latino population. However, there is limited information about tomatillo production. The objectives of this study were to determine the effects of plastic mulches on plant growth, yield, and root zone temperature in two cultivars of tomatillo. The study was conducted in Spring and Summer 2000. The design was a randomized complete block with a split plot arrangement, where plastic film mulch (black, gray, and silver mulches, and bare soil) was the main plot and cultivar (`Toma Verde' and `Verde Puebla]) the subplot. In the spring, mulch treatments had little effect on plant growth during the first 30 days after transplanting and there were no significant differences in fruit yields. In the summer planting, both early growth and fruit yields were greatest with the silver and gray mulch treatments and lowest on bare soil. Plant growth during the establishment was related with subsequent plant growth and yield. In mature plants, vegetative top fresh weight and total fruit yield were higher (P < 0.01) in the spring than in the summer. Total fruit yield (both seasons), marketable yield (spring) and cull yield (spring) were lower in `Toma Verde' than in `Verde Puebla'. Root zone temperatures (RZTs) in the spring (mean = 26.4 °C) were lower than in the summer (mean = 29.3 °C). In both seasons, mean RZT was highest under black mulch and lowest in bare soil. In the summer, plant growth and fruit yields tended to decrease with increasing RZTs. Tomatillo plants grown on mulches with a mean seasonal RZT of 30 °C had fruit yields that were 65% (`Toma Verde') or 50% (`Verde Puebla') lower respectively than those of plants on mulches with a RZT of 27 °C. There were no significant differences in foliar concentrations of N, Ca, Mg, S, B, Zn, Cu and Na among mulches. Foliar concentrations of the majority of mineral nutrients were not related with the mean RZT for the season.

(181) Effect of Mulch, Mycorrhizal Inoculation, and Surround on Late Fall Pepper Production

Four week-old pepper (Capsicum annuum) cultivars Sonora Anaheim and Capistrano were transplanted on 7 Oct. 2004 into a sandy loam soil near Weslaco, Texas (lat. 26°08'N). Plants were subject to eight treatments consisting of sweet sorghum mulch, mycorrhizal (Bio Organics) inoculation, kaolin (Surround) application and their factorial combinations. Mulch was applied at 2.4 kg·m-2 and kaolin weekly at 25 kg·ha-1. Mulch applications reduced soil temperatures at 5 cm typically 8 °C during the 1200–1800 HR period of the day during the first 14 days after planting, but decreased soil temperatures to less than 2 °C by 22 Dec. Volumetric soil moisture content at 0–20 cm was initially 4% (absolute) higher in the mulch treatments during the first week after planting but deceased with time as the mulch deteriorated. Mulching increased root dry weight 70 days after transplanting. Mycorrhizal association was evaluated in four treatments, where incidence of mycorrhizal infection was “mulch + mycorrhizae” > “mycorrhizae only” = `“mulch only” » “control.” Kaolin reduced plant height, plant top fresh weight, and improved yield in both cultivars by increasing earlier flowering and, in the case of `Sonora Anaheim', reducing fruit drop caused by pepper weevil (Anthonomus eugenii). In both cultivars, mulch reduced yields and mycorrhizal inoculation gave no agronomic benefit.

Host-parasite relationships in tobacco plants infected with a root-knot nematode (Meloidogyne incognita) population from the Azores

During a nematode survey, severe infections of tobacco feeder roots and heavy soil infestations byMeloidogyne incognita race 1 were found in S. Miguel (Azores islands, Portugal). This is the first record ofM. incognita infection of tobacco in Azores. Morphology of various life stages, analysis of the esterase electrophoretic pattern and differential host tests were used for nematode characterization and identification. Nematode-induced mature galls were spherical and/or ellipsoidal and usually contained more than one female, males and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density and growth of tobacco plants was tested in a glasshouse experiment in which inoculum levels varied from 0 to 512 eggs and juveniles (J2) cm−3 of soil. Seinhorst’s model was fitted to height and top fresh weight data of the inoculated and control plants. Tolerance limits with respect to plant height and fresh top weight of tobacco cv. ‘Erzegovina’ plants toM. incognita race 1 were estimated as 1.25 eggs and J2 cm−3 of soil. The maximum nematode reproduction rate was 404.7 at an initial population density of 4 eggs and J2 cm−3 of soil.

Growth and Yield of Tomato on Plastic Film Mulches as Affected byTomato Spotted Wilt Virus

Tomato spotted wilt virus (TSWV) is a serious constraint to tomato production worldwide. Losses are significant because the disease is difficult to control and most of the commercially available tomato cultivars are susceptible to TSWV. This study was intended to provide information that could be used to design more appropriate disease management strategies. The objective was to determine the relationship of tomato plant growth and fruit yield with the time of TSWV symptom appearance. Experiments were carried out during Spring 1999 and 2000, using drip irrigation and plastic film mulched beds with black plastic mulch alone (1999) or different colored mulches (2000). The mulches used were black, black-on-silver, gray-on-black, red, silver-on-black, silver (painted) and white-on-black, and bare soil. The 1999 experiment included a single TSWV-susceptible cultivar (Florida-47), while the 2000-experiment included two TSWV-susceptible (Florida-91 and Sun Chaser) and one TSWV-resistant cultivars (BHN-444). Colored mulches and tomato cultivars affected the time between transplanting and appearance of first symptoms of TSWV. For all tomato cultivars, vegetative top fresh weight (FW), fruit number and total fruit yield increased linearly with the time the plants remained free from TSWV symptoms. Marketable fruit yield also increased as the time from transplanting to the first appearance of symptoms increased. When data for cultivars were pooled, vegetative top FW and total fruit yield were reduced by 2.1% and 2.3%, respectively, for each day prior to harvesting that plants showed TSWV symptoms.

Further Contributions to the Development of a Differential Set of Pea Cultivars ( Pisum sativum ) to Investigate the Virulence of Isolates of Aphanomyces euteiches

Common root rot (Aphanomyces euteiches Drechs.) has become a very destructive disease in the French pea crops since 1993. For an accurate investigation of the virulence variability among French A. euteiches populations and between French and foreign populations, a new set of differential pea genotypes was developed. Thirty-three American and European pea lines, displaying different levels of resistance, were screened in a growth chamber against two French isolates. Symptoms (disease severity from 0 to 5, evaluating symptom surface on roots and epicotyl) and percentage of top fresh weight (inoculated/uninoculated top fresh weight ratio) were measured. From this screening 12 relatively resistant lines, from various genetic backgrounds, were identified along with a highly susceptible control. This set of 13 genotypes was inoculated under controlled conditions with 14 isolates from France, Sweden, USA, Canada and New Zealand, to investigate genotype–isolate interactions. Root symptoms were rated (disease severity), and a susceptibility/resistance threshold was established at disease severity = 1. Significant quantitative interactions were observed, and five 'resistance patterns' were identified, leading to a set of six pea genotypes: Baccara (susceptible), Capella, MN313, 902131, 552 and PI180693. Fields trials of this set in 1999 and 2000 gave the same resistance rankings than in growth chamber conditions. This set will allow more accurate assessments of the variability in virulence/aggressiveness of A. euteiches isolates from France and foreign countries, and further investigations of the epidemiological and genetic basis of pea–A. euteiches interactions.

Colored Plastic Film Mulches Affect Tomato Growth and Yield Via Changes in Root-zone Temperature

Soil warming is one of the benefits associated with use of plastic film mulches. However, under high temperature conditions during the summer, especially in the southeastern United States, some mulches warm the soil to temperatures that might be deleterious to plant growth. Tomato (Lycopersicon esculentum Mill.) plants grown in the field were exposed to a range of root-zone temperatures (RZTs), resulting from growing the plants in different seasons and by using colored mulches that differed in their soil-warming ability. The objective was to determine the relationship of mean seasonal RZT, as affected by different colored plastic film mulches, with plant growth and fruit yield. The study consisted of experiments carried out in three seasons: Fall 1999 (five mulches, one cultivar), Spring 2000 (eight mulches and three cultivars), and Fall 2000 (four mulches and three cultivars). Treatments were black (n = 2), gray, red, silver (n = 3), and white (n = 2) mulches, and bare soil. Over the season, mean RZT decreased in the fall (from 32 to 24 °C) and increased in the spring (from 20 to 29 °C). Daily mean values of RZT over the season under plastic mulches were higher (1 to 5 °C) than those of air temperature. The highest RZT at midday occurred under black mulch, and the lowest under bare soil and white mulch. Bare soil showed the largest diurnal RZT fluctuation. RZT at midday was up to 4 °C higher under black or gray mulch compared to the other mulches or bare soil. The degree of soil warming was correlated with reflectivity of the mulch. Black mulch had the lowest light reflectance [10% photosynthetically active radiation (PAR)] while silver mulch had the highest (55% PAR). There were, however, differences in reflectance among mulches of the same color depending on the manufacturer. RZT affected vegetative top fresh weight (FW), fruit yield, fruit number, and individual fruit FW. All these growth attributes fitted a quadratic relationship with mean RZT for the season, with an optimal that ranged between 25.4 and 26.3 °C. The effects of colored mulches on plant response depended on the impact of the mulch on RZT. Plant growth and yield were highest as RZT approached the optimal RZT for the plants.

Biological Control of the Root-Knot Nematode Meloidogyne javanica by Trichoderma harzianum

ABSTRACT The fungal biocontrol agent, Trichoderma harzianum, was evaluated for its potential to control the root-knot nematode Meloidogyne javanica. In greenhouse experiments, root galling was reduced and top fresh weight increased in nematode-infected tomatoes following soil pretreatment with Trichoderma peat-bran preparations. The use of a proteinase Prb1-transformed line (P-2) that contains multiple copies of this gene improved biocontrol activity in the greenhouse experiments compared with the nontransformed wild-type strain (WT). All the Trichoderma strains showed the ability to colonize M. javanica-separated eggs and second-stage juveniles (J2) in sterile in vitro assays, whereas P-2 also penetrated the egg masses. This protease-transformed line presented the same nematicidal and overall proteolytic activity as the WT in in vitro tests in which concentrated soil extracts from Trichoderma-treated soils immobilized the infective J2. However, the J2 immobilization and proteolytic activities of both P-2 and the WT were higher than those obtained with strain T-203. Characterization of the activity of all Trichoderma strains soil extracts on J2 showed that it was heat resistant and restricted to the low-molecular-weight fraction (less than 3 kDa). It is suggested that improved proteolytic activity of the antagonist may be important for the biological control of the nematodes.

Host-Parasite Relationships in Root-Knot Disease of White Mulberry.

Severe infections of white mulberry feeder roots and heavy soil infestations by Meloidogyne arenaria race 2 were found in southern Spain. This is the first record of M. arenaria on white mulberry in Europe. Morphometric observations, analysis of the esterase electrophoretic pattern, and artificial inoculations of race differentials were used to characterize nematodes. Nematode-induced mature galls were spherical and usually contained one or more females, males, and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density (Pi) in a series from 0 to 1,024 eggs and juveniles/cm3 soil and growth of white mulberry seedlings was tested in the greenhouse. A Seinhorst model was fitted to plant height and top fresh weight. Tolerance limits of white mulberry to M. arenaria race 2 for plant height and top fresh weight were, respectively, 1.1 and 1.38 eggs and juveniles/cm3 soil. The minimum relative values for plant height and top fresh weight were 0 at Pi ≥ 64 and Pi ≥ 128 eggs and juveniles/cm3 soil, respectively. Maximum nematode reproduction rate was 435-fold at the lowest Pi.

Effects of Temperature, Shade, and Nitrogen Application on the Growth and Accumulation of Bioactive Compounds in Cultivars of Plantago lanceolata L.

Effects of temperature, shade, and nitrogen application on the growth and contents of bioactive compounds in Plantago lanceolata L. were investigated by using two cultivars in a controlled environment. The cultivars that were grown at 15°C/10°C day/night temperatures were higher in top dry-matter weight, top dry-matter content, and the contents of acteoside, the phenylehtanoid glycosides, compared to those that were grown at 20°C/18°C temperatures. On the other hand, the contents of catalpol and aucubin, the iridoid glucosides, were higher in the plants grown at 20°C/18°C temperatures. It is assumed that the response of the accumulation of the compounds to temperature is different between phenylehtanoid and iridoid glucosides. Plants grown under shading treatment were lower in number of leaves per plant, top dry matter weights, and top dry matter contents, though they were higher in plant height. The contents of aucubin and acteoside were extremely lower in plants grown in the shade. It is apparent that shade represses the growth and accumulation of aucubin and acteoside in the cultivars of Plantago lanceolata L. Nitrogen application enhances the growth of the cultivars, especially the top fresh weight; on the other hand, it significantly diminished the top dry-matter content. The contents of aucubin and acteoside were apparently lower in the plants treated with nitrogen than in those that did not receive it.

人工光源による深夜補光が数種水耕そ菜の生育に及ぼす影響

Effects of supplemental lighting 23 : 00-7 : 00 on the growth and photosynthesis of vegetable crops were studied. In Experiment 1, lettuce (Lactuca sativa L.), pakchoi (Brassica campestris L. var. chinensis) and tsukena (Brassica campestris L.) grown on NFT in a greenhouse, were subjected to supplemental lighting with high pressure sodium lamps. Plants were grown for 24 days under normal photoperiod and then separated into 5 groups, as follows ; subjected to supplemental lighting 1) for 24 days, 2) first 8 days, 3) the second 8 days, 4) the last 8days of the 24 days period and control continued natural photoperiod. In Experiment 2, lettuce, garland chrysanthemum (Chrysanthemum coronarium L.) and tomato (Lycopersicon esculentum Mill.) plants were grown under the light source and 1, 2, and 3m apart horizontally away from the light source. Results obtained are as follows ; 1. In Experiment 1, supplemental lighting for 24 days increased top fresh weights of all crops. In lettuce and pakchoi, the supplemental lighting for the second 8 or last 8 days increased the top fresh weights when compared to the control. 2. In lettuce, garland chrysanthemum, and tomato, growth increased with increasing light intensity of the supplemental lighting ; in garland chrysanthemum it enhanced the dry weights of stems. 3. Supplemental lighting increased the chlorophyll concentrations as measured with a Minolta chlorophyll meter, SPAD-502 ; the increment levels corresponded to the light intensity of the supplemental lighting. The increases in SPAD values under supplemental lighting appeared on the 8th day after the onset of the supplemental lighting. However the elevated SPAD values resulting from supplemental lighting decreased to the same levels as the control during the subsequent 8 days when supplemental lighting was halted. 4. Supplemental lighting during the night accelerated the photosynthetic rates of lettuce, garland chrysanthemum, and tomato plants. In addition, plants grown under supplemental lighting maintained a higher photosynthetic rates during the day than the control plants did.

303 Effect of Growth Regulators on the Growth and Performance of Celosia plumosus

Seedlings of Celosia plumosus `New Look', a new variety, were evaluated for their response to the recommended rates of three different plant growth regulators commonly used by growers. The plant growth regulators were B-nine, paclobutrazol, and uniconizole. These plant growth regulators were applied at the rate recommended by the manufacturer for this species. Group I, the control, was not treated with a plant growth regulator, but was sprayed with water at the same time the other treatments were applied. Plants were grown in 5-inch plastic pots in the greenhouse. Plant height was recorded before treatment and once weekly thereafter for the duration of the experiment. Upon termination of the experiment, plant top fresh weight and top dry weight were measured. Results showed that at the recommended rate for all three plant growth regulators, there were no significant difference in height or weight between the plant growth regulator-treated groups of plants or the control group. The only observable difference noted was in leaf coloration of the plants treated with plant growth regulators.

収穫前のＮＯ３‐Ｎまたは全肥料成分の補給停止が水耕ホウレンソウの生育と可食部の硝酸濃度ならびに廃液の無機成分濃度に及ぼす影響

NFT毛管水耕システムを用いたホウレンソウ(Spinacia oleracea L.品種'ジョーカー'および'オリオン')栽培において, 収穫前にNO3-Nのみの補給停止(実験1 : 夏作), または全肥料成分の補給停止(実験2 : 秋作)が, 生育, 可食部の硝酸含量, 廃液の無機成分濃度に及ぼす影響を検討した.実験1 : 収穫6日前からのNO3-Nの補給停止で, 可食部の硝酸含量は2, 199 ppm, 廃液のNO3-N濃度は1.0 me・liter-1と, 食品・廃液の許容基準を満たすことができた.NO3-N以外の成分は初期濃度と同じか, それ以上に廃液中に残存した.実験2 : 2∿6日前からの追肥停止で, 廃液のNO3-N濃度は0.7 me・liter-1以下, 可食部の硝酸含量は2, 870 ppm以下となり, 食品・廃液の許容基準を満たすことができた.さらに, 他の主要無機成分についても, 残存濃度を低減できた.しかし, 6日前からの追肥停止では, 地上部生体重が低下した.以上より, 夏作で収穫予定日の6日前, 秋作では2∿4日前から, 肥料成分を含まない水を補給する方法が, 可食部の硝酸濃度の低いホウレンソウの生産と, 廃液中の主要無機成分含量の低減に有効と考えられた.