Maximum Seedling Research Articles

Allelopathic Effect of Powdered Russian Knapweed (Acroptilon repens L.) on the Growth Parameters of Redroot Amaranth (Amaranthus retroflexus L.)

To evaluate probable allelopathic effect of different parts of Russian knapweed (Acroptilon repens L.) on the growth of redroot amaranth (Amaranthus retroflexus L.) seedling, a factorial experiment was conducted based on randomized complete block design with three replications at the Faculty of Agriculture, Urmia University in 2012 (Iran). In this experiment, treatments were different parts of Russian knapweed (aerial part, flower and root) in different amounts (1, 2, 3 and 4 g/pot). Pots included 300 g of soil. Results showed the significant effect of Russian knapweed plant parts on the seedling emergence percent, root length, ratio of root/shoot length, seedling length, seedling fresh weight, and the significant effect of plant material amounts on the seedling emergence percent, seedling fresh weight and seedling dry weight. Interaction effect between plant material type and amount on the shoot length, root length, ratio of root/shoot length, seedling length was significant, too. The longest shoot (3.51 cm), root (1.75 cm), the highest ratio of root/shoot length (0.49) and seedling length (5.26 cm) belonged to control treatment. The highest seedling emergence percent of Amaranthus retroflexus (34.73%) and seedling fresh weight (0.176 g) were occurred at pots treated by Russian knapweed aerial part. The lowest seedling emergence percent (21.94 %) and seedling fresh weight (0.111 g) were obtained from application of Acroptilon repens powdered root. The maximum seedling dry (0.0126 g) and fresh (0.177 g) weight of Amaranthus retroflexus were obtained from control treatment.

Effect of sowing time on field emergence and growth of South African grassland species

This study investigated seedling emergence in field sowings in terms of rate, and maximum seedling emergence, for twenty one species of forb, grass and geophyte species associated with montane South African grassland communities. Species were sown in early and late spring to compare the effect of sowing date on emergence characteristics and subsequent growth. RGR and mean individual standing biomass were calculated for a 150day post sowing growth window. Species showed highly significant differences in the time taken to achieve 50% emergence, and species rankings on this basis changed according to the date of sowing. There were large differences in RGR between species that were also reflected in mean standing biomass per individual. The data provide a basis for a preliminary, comparative ecological characterization of these species and an insight into how these species establish and potentially avoid competitive elimination in mixed sowings in restoration ecology or in landscape architecture, in the first growing season. The study also provides some indication on how emergence and growth of individual species might affect recruitment and survival in their habitats.

Germination ecology of Rhynchosia capitata: an emerging summer weed in Asia

Rhynchosia capitata is becoming an increasing problem in summer crops, such as cotton, soybean, pearl millet and mungbean in many Asian countries. Laboratory and greenhouse studies have been conducted to determine the effects of several environmental factors on seed germination patterns and seedling emergence of R. capitata. We investigated whether the diverse ecological factors such as temperature, light, salinity, moisture stress, pH, and soil depth affected germination and seedling emergence of R. capitata. Germination increased as temperature increased from 25ºC and significantly reduced at 45ºC. Presence or absence of light did not influence germination. Germination of R. capitata was sensitive to increased salt and moisture stress, as well as to seed burial depth. Only 48% of seeds germinated at 150 mM salt concentration compared to 100% in control (distilled water). Similarly, 15% of seeds germinated at an osmotic potential of ‑0.8 MPa compared to 88% at ‑0.2 MPa. The optimum pH for seed germination of R. capitata was 7 (98% germination), but the seeds also germinated at lower level of pH 5 (85%) and at higher level of pH 10 (75%). In seed burial trial, maximum seedling emergence of 93% occurred at 2 cm depth, and seedling did not emerge from a depth of 12 cm. The high germination ability of R. capitata under a wide range of ecological factors suggests that this species is likely to be the one to cause more problems in a near future, if not managed appropriately.

Seed germination and seedling emergence of velvetleaf (Abutilon theophrasti) and Barnyardgrass (Echinochloa crus-galli)

Abutilon theophrasti and Barnyardgrass (Echinochloa crus-galli) are major weeds that affect cropping systems worldwide. Laboratory and greenhouse studies were conducted to determine the effects of temperature, pH, water and salinity stress, and planting depth on seed germination and seedling emergence of Velvetleaf and Barnyardgrass. For Velvetleaf, the base, optimum and ceiling germination temperatures were estimated as 5, 35 and 48 ºC, respectively. Seed germination was sensitive to drought stress and completely inhibited by a potential of -0.6 MPa, but it was tolerant to salinity. Salinity stress up to 45 mM had no effect on the germination of Velvetleaf, but germination decreased with increasing salt concentration. Drought and salinity levels for 50% inhibition of maximum germination were -0.3 MPa and 110 mM, respectively. Seed germination of Velvetleaf was tolerant to a wide range of pH levels. For Barnyardgrass, the base, optimum and ceiling germination temperatures were estimated as 5, 38 and 45 ºC, respectively. Seed germination was tolerant to drought stress and completely inhibited by a potential of -1.0 MPa. Salinity stress up to 250 mM had no effect on seed germination. Drought and salinity levels for 50% inhibition of maximum germination were -0.5 MPa and 307 mM, respectively. A high percentage of seed germination was observed at pH=5 and decreased to 61.5% at acidic medium (pH 4) and to 11% at alkaline medium (pH 9). Maximum seedling emergence of Velvetleaf and Barnyardgrass occurred when the seeds were placed on the surface of the soil or at a depth of 1 cm.

A new phenotyping technique for screening for drought tolerance in lentil (Lens culinaris Medik.)

AbstractScreening for drought tolerance is severely handicapped by the lack of a simple and reliable phenotyping technique. The objective of this study was to develop a new screening technique based on seedling survivability, drought tolerance score, root and shoot length, and fresh and dry weight of roots and shoots of lentil plants exposed to drought under hydroponic conditions. Its effectiveness was compared with two soil culture techniques. The hydroponic technique involved removing 15‐day‐old seedlings of 80 genotypes from the nutrient solution and exposing them to air for 5 h daily for 6 days. Three genotypes received from ICARDA, ‘ILL‐10700’, ‘ILL‐10823’ and ‘FLIP‐96‐51’, showed maximum seedling survivability and minimum reduction in the growth parameters with a drought score of 0.0–0.2 indicating higher tolerance to drought stress, while Indian genotypes ‘JL‐3’, ‘E‐153’ and ‘VL‐507’ showed no seedling survivability and maximum reduction in growth parameters with a drought score of 4.0 indicating low drought tolerance. The results suggest that this new phenotyping technique is effective, rapid and easy for screening a large number of genotypes.

An Evaluation of the Effects of Organic and Inorganic Fertilizers on the Growth Performance of Three Timber Species: Cedrella odorata L., Entandrophragma angolensis Welw. and Terminalia superba Diel., in Nursery

Aim: To evaluate the effects of fertilization on the growth performance of Cedrella odorata, Entandrophragma angolensis and Terminalia superba in nursery. Study Design: A complete randomized block design was used. Place and Duration of the Study: Screen house of the Department of Botany and Plant Physiology, from September 2011 to July 2012. Methodology: We used 10 nutrient treatments, nine of which were nutrient combinations and one, a negative control. Urea was added at 75 mg and 112.50 mg while super phosphate simple was added at 30 mg and 60 mg. Poultry manure from broilers was added at 625 g. A total of 180 uniformly growing seedlings were treated with fertilizers two weeks after transplanting. There were six replicates per treatment per species. Research Article British Journal of Applied Science & Technology, 3(4): 1044-1054, 2013 1045 Information on height (cm), collar diameter (mm), leaf number, leaf area (cm) and biomass production (g) was collected fortnightly from the day of fertilizer application, for a 120 days period. Results: Cedrella odorata produced maximum seedling height (13.55 cm), leaf number (9.99), leaf area (509.20 cm) and total biomass (18.47g), Terminalia superba showed maximum collar diameter (4.78 mm) while Entandrophragma angolensis had the least growth performances. Conclusion: Fertilization of seedlings of threatened species in nursery would be necessary, because this will ensure their survival and improve their regeneration following out planting.

Rice Husk Biochar Influences Seedling Emergence of Junglerice (<i>Echinochloa colona</i>) and Herbicide Efficacy

The use of carbonized rice husk biochar improves the fertility and productivity of poor soils in rice-based cropping systems. However, biochar may also influence weed seedling emergence and the efficacy of soil-applied herbicides. Experiments were conducted in a screenhouse to evaluate the effect of biochar rates (0, 20, 40, and 80 t·ha?1) and seed burial depth (0, 1, and 2 cm) on seedling emergence of junglerice (Echinochloa colona) and the effect of biochar rates and pendimethalin (0, 500, 1000, and 1500 g·a.i.·ha?1) and pretilachlor doses (0, 300, 600, and 900 g·a.i.·ha?1) on seedling emergence and seedling biomass of junglerice. Data were analyzed using nonlinear regression. The burial depth to inhibit 50% of maximum seedling emergence was 0.76 cm when biochar was not added to soil and the depth increased with an increase in biochar rates for soil. Similarly, compared with the soil with no biochar, the use of bichoar increased the pretilachlor dose to inhibit 50% of maximum emergence or biomass. The pretilachlor dose to inhibit 50% of maximum biomass of junglerice was 100, 130, 240, and 240 g·ha?1 when biochar was added at 0, 20, 40, and 80 t·ha?1. However, the efficacy of pendimethalin was not influenced by biochar rate. The results of this study suggest that rice husk biochar may increase weed seedling emergence from deeper burial depths and may decrease the efficacy of some soil-applied herbicides.

Influence of Vam and Rhizobium Inoculation at Different Levels of N and P on Seedlings Growth in Dalbergia Sissoo

A study was carried out to see the effect of VAM, Rhizobium and inorganic fertilizers, alone and in combination, on plant growth in Dalbergia sissoo. Nine combinations comprising three levels of nitrogen and three levels of phosphorus were main plot treatments and four biofertilizers levels (No inoculation, VAM, Rhizobium) served as sub plot treatments. Significantly higher seedling length and diameter were recorded in dually inoculated plants than in VAM or Rhizobium inoculation alone. Nitrogen x phosphorus, phosphorus x bioferrtilizer and nitrogen x phosphorus x biofertilizer interactions also resulted in significant increased plant growth. Among all treatment combinations, dual inoculation of VAM + Rhizobium supplemented with 30kg Nha-1 and 75kg P2O5 ha-1 produced maximum seedling length and diameter. Desirable plantable size for field planting was achieved within six months after sowing (by the end September in the same season) in treatment combinations N30P75B (VAM + Rhizobium), N30P150B (VAM + Rhizobium) and N60P150B0 (No biofertilizer inoculation) thus saving resources I terms of time, space and money.

Isabgol (Plantago ovata Forsk) seed germination and emergence as affected by environmental factors and planting depth

Isabgol (Plantago ovata Forsk) seed germination and emergence in response to drought (Polyethylene glycol 8000) and salinity stress (NaCl), temperature, pH and planting depth were studied in laboratory and greenhouse experiments. Base, optimum and ceiling germination temperature were estimated as 3.35, 21.24 and 35.04 o C, respectively. Isabgol seed is rather tolerant to low water potential and high salt stress. Salinity stress up to 200 mM had no effect on Isabgol seed germination, but the germination decreased by increasing the salt concentration. The drought and salinity required for 50% inhibition of maximum germination were 328 mM and - 1.24 MPa, respectively. High percentage of seed germination (>93%) was observed at pH=4-6 and declined to 52-58% at alkaline (pH 7-9) pH. Maximum seedling emergence occurred when the seeds were planted on the soil surface and decreased with increasing the depth of planting; no seed emerged from depth of 3 cm.

Priming with moringa leaf extract reduces imbibitional chilling injury in spring maize

This study investigated the potential of moringa leaf extract (MLE) in seed priming for vigour enhancement of spring maize sown at low temperature (12 ± 1°C). The efficacy of MLE priming (3% w/v) was compared with other priming agents: kinetin (0.5% w/v), KCl (2% w/v) and hydropriming, each for 18 hours in hybrid maize cv. Pioneer-6525. Non-primed seeds were used as the control. Priming with MLE was the most effective in improving germination rate and subsequent seedling growth. This increased seedling performance was the result of reduced time to 50% germination (T50) and mean germination time (MGT), and higher final germination percentage (FGP), germination index (GI) and germination energy (GE). Similarly improved seedling growth following seed priming with MLE or kinetin was due to enhanced root and shoot lengths, the ratio of root:shoot length and maximum seedling fresh and dry weights compared with control seeds. Enhanced seedling maize performance by priming with MLE was attributed to improved chlorophyll content, amylase activity and total sugar contents under cool conditions.

Evaluation of natural products for the management of damping-off of tomato incited byPythium aphanidermatum(Edson) fitz

The effect of various natural products from plants and animals were evaluated for the presence of antifungal activity against Pythium aphanidermatum causing damping-off of tomato. Among the plant species tested, bulbs of A. sativum (10%) and Allium cepa var. aggregatum (20%), leaves of Lawsonia inermis, Piper betle (20% each), Eucalyptus globulus and Vitex negundo (40% each) exhibited complete inhibition of the mycelial growth of P. aphanidermatum. Out of 4 animal excreta screened, Pig dung (40%) extract totally inhibited the mycelial growth of P. aphanidermatum. Garlic bulb, eucalyptus leaf and hen litter extract were found to retain the fungitoxicity when extracted at 80 °C for 10 minutes. A. sativum bulb followed by E. globulus leaf extracted in acetone was found to be significantly superior over other natural products. Among the natural products tested, the minimum mycelial dry weight of P. aphanidermatum was obtained with garlic bulb followed by eucalyptus leaf extract. The plant products combined together retained strong inhibitory effect in solid and liquid media against P. aphanidermatum. Upon mixing, the more loss of toxicity was observed when botanicals were mixed with animal excreta, particularly with pig dung. Among the natural products tested, the water extracts of A. sativum plus E. globulus and A. sativum plus L. inermis combinations recorded the maximum percentage of seed germination, growth and vigour of tomato seedlings, respectively. Also, when the various natural products tested by seed treatment, soil drenching and seed treatment plus soil drenching, garlic plus eucalyptus treatment recorded maximum seedling emergence and lesser damping off incidence in all three methods of application. Among the three methods, seed treatment plus soil drenching (St+Sd) was found to be superior than other two methods.

Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA

A field experiment was conducted using a 3 × 3 orthogonal regression design to explore the growth promotion of one-year-old Yunnan pine seedlings (Pinus yunnanensis Franch.) in response to foliar application of IAA (indole-3-acetic acid) at rates of 0, 200 and 400 mg·L−1 and IBA (indole-3-butyric acid) at rates of 0, 200 and 400 mg·L−1 in order to promote the growth during the seedlings’ early stage. The experiment was conducted at the Lufeng Village Forest Farm of Yiliang County in Kunming, Yunnan, China. The results showed that IAA and IBA were effective in growth promotion of Yunnan pine seedlings. The response of both growth increment and biomass accumulation to the concentration of IAA and IBA can be modeled using a bivariate surface response, and each growth index had a peak value. Growth indexes increased with the increase of the dosage of photohormones before reaching a peak value, and then decreased. The different growth indexes had various responses to the concentrations and ratio of IAA and IBA. The foliar application of IAA in combination with IBA showed the largest improvement on the biomass of the needles, followed by stems and roots. The higher ratio of IAA promoted stem diameter growth, root system development and biomass accumulation in the needles, while a higher ratio of IBA contributed to height growth and biomass accumulation in the stem. Based on the auxin effect equations on the different growth indexes and surface response, the optimum concentrations and the (IAA:IBA) ratios can be obtained. The optimum concentrations of IAA and IBA were 167 and 186, 310 and 217, 193 and 159, 191 and 221, and 206 and 186 mg·L−1, with corresponding ratios of 1:1.11, 1:0.70, 1:0.82, 1:1.15 and 1:0.90, respectively, at the maximum seedling height and collar diameter growth as well as biomass accumulation at the root, stem and needle. The above growth indexes were 22.00%, 79.80%, 48.65%, 82.20% and 107.00% higher than the control treatment.

BIOSSÓLIDO NA COMPOSIÇÃO DE SUBSTRATO PARA A PRODUÇÃO DE MUDAS DE Tectona grandis

Este estudo teve por objetivo avaliar o efeito do biossólido como componente do substrato para produção de mudas de Tectona grandis Linn. F. O experimento foi realizado em seis tratamentos com cinco repetições cada, sendo cada repetição constituída da média de cinco mudas. Os tratamentos foram formulados com as seguintes proporções de biossólido:substrato comercial (v:v); T1-20:80; T2-40:60; T3-60:40; T4-80:20; T5-100:0 e T6-0:100. Após 120 dias, as mudas foram coletadas para determinação das seguintes variáveis morfológicas: diâmetro do coleto, altura da parte aérea, relação entre a altura da parte aérea e o diâmetro do coleto, massa seca da parte aérea, sistema radicular e massa seca total, relação entre a matéria seca da parte aérea e a matéria seca do sistema radicular e índice de qualidade de Dickson. O biossólido favoreceu o crescimento das mudas de Tectona grandis. O máximo crescimento das mudas foi verificado quando se utilizou 60% a 100% de biossólido associado ao substrato comercial, o qual proporcionou melhores crescimentos dos parâmetros altura da parte aérea, diâmetro do coleto, massa seca total e índice de qualidade de Dickson.

Effect of Vermicompost and Habitat soil on Seedling growth of White Cedar (Dysoxylum Malabaricum Bedd. Ex Hiern): An Endangered Timber species of the Western Ghats

Dysoxylum malabaricum (White Cedar) is one of the highly priced timbers yielding species endemic to the Western Ghats. It is highly valued for its lustrous, sweet-scented and durable timber and mainly used for construction of temples. Its wood properties are comparable with that of teak. Populations of D. malabaricum are too scanty and less reported. The species has been subjected to severe illegal felling in the natural forest, hence it has caused concerns among conservation biologists. Recently, Karnataka Forest Department has planned to take up large-scale plantation programme of this species. However, there are no reports related to standardization of nursery techniques for this species. Evaluation of seedlings for their growing media is an important step for nursery rising. The present study was under taken to know the effect of vermicompost and habitat soil on early growth of seedlings in D. malabaricum. Result showed that potting mixtures containing red soil as one of the components of potting mixture recorded maximum seedling height, collar diameter and number of leaves per plant when compared to those potting mixture containing habitat soil. Interestingly, there was a negative influence of vermicompost on seedling growth, where the treatment, containing soil, sand and vermicompost in the proportion of 1:1:1 (T2) showed poor growth as compared to potting mixture containing soil, sand and vermicompost in the ratio of 1:1: ½ (T3). This suggests that use of vermicompost may not always beneficial to the plant growth in Dysoxylum malabaricum.

Germination in Zostera japonica is determined by cold stratification, tidal elevation and sediment type

The effects of water temperature and bottom sediment type were studied on seed dormancy and germination of Zostera japonica Ascherson & Graebner in mesocosm. To test whether the germination rate is affected by cold stratification, seeds were divided into two groups: those exposed to cold (7 °C) and those left untreated (23–15 °C). Additionally, to mimic tidal variation, we used five tidal depth treatments for germination experiments in mesocosm. In mesocosm tanks, there was a wide range of daily fluctuating temperature at datum line +40 cm (17–25 °C), D.L. +20 cm (15 °C), and D.L. +0 cm (4–7 °C). In contrast, the maximum temperature range at D.L. −20 cm and −40 cm was narrow (5–6 °C). In the no cold stratification group, the maximum germination rates on sandy, muddy sand, and muddy bottom sediment were 3%, 11%, and 3%, respectively. In the cold stratification group (7 °C), the maximum germination rates were 40%, 53%, and 54%, respectively. First germination was observed 36 ± 0 days and 43 ± 6 days after the start of the germination experiment in the cold stratification group and the no cold stratification group, respectively. Bottom sediment type and tidal level did not affect seed germination in the both stratification group. Cold stratification strongly increases germination in all sediment types tested and under varying temperature regimes and at different tidal levels. We also tested whether seed germination is affected by daily fluctuations in temperature (10 °C constant, 15 °C/10 °C, and 20 °C/10 °C were compared) in an indoor incubator. Forty-two days after being sown, the maximum seedling emergence rates in the three groups were 3 ± 5%, 21 ± 7%, and 42 ± 26%, respectively. At 20 °C/10 °C, first germination was observed 11 days after the start of incubation, the germination rate rose sharply after 18 day of incubation, and then it leveled off after 32–42 days of incubation. In the no cold stratification group, seed germination was not observed in any of the three treatments. This finding suggests that the breaking of seed dormancy and germination of Z. japonica seeds are determined strongly by cold temperature and daily fluctuations of temperature, respectively.

Seed Development and Quality in Maize Cultivars

In order to evaluate seed development and quality of maize (Zea mays) cultivars (DC-370, SC-500, OSSK-602 and SC-604), a split plot experiment (using R.C.B. design) with three replicates was conducted in 2009 at the Research Farm of the Faculty of Agriculture, University of Tabriz, Iran. Seeds were harvested at five day intervals in eight stages. Subsequently, the quality of seed samples was determined in the laboratory. Germination percentage and seedling dry weight were enhanced, but electrical conductivity of seed leachates was reduced with increasing seed weight on mother plant. Maximum seed quality of maize cultivars was attained at the end of seed filling phase. Seed quality at earlier harvests was low, because of immaturity. Differences in maximum seedling dry weight of maize cultivars were attributed to variation in genetic constitution. It was concluded that in maize cultivars, maximum seed quality could be achieved at physiological maturity.

Development of Seed Physiological Quality in Winter Oilseed Rape (Brassica napus L.) Cultivars

Stage of maturity at harvest is one of the most important factors that can influence the quality of seeds. This research was carried out in 2008- 2009 to evaluate the development of physiological seed quality in three winter oilseed rape (Brassica napus L.) cultivars (Modena, Opera and SLM046). Seeds were harvested serially in 9-10 stages during their development and maturation. Maximum seed weight (mass maturity) was achieved at 48-54 days after flowering, when seed moisture content was 41-50%. However, maximum seed quality as measured by seed viability, germination percentage, germination rate and seedling dry weight was obtained 10 to 22 days after mass maturity. Thereafter, seed quality of all cultivars was started to decrease, due to ageing. Maximum germination rate of SLM046 and maximum seedling dry weight of Opera were significantly higher than those of other two cultivars. These variations in seed quality parameters were attributed to differences in genetic constitution among oilseed rape cultivars. It was concluded that high quality seeds of winter oilseed rape cultivars could be produced with 14-16% moisture content, which is suitable for direct and mechanical harvesting, threshing and storage without further drying.

Achene buoyancy and germinability of the terrestrial invasive Fallopia × bohemica in aquatic environment: A new vector of dispersion?

Seed dispersal along watercourses can favour the long-distance migration of invasive species, not only for aquatic or wetland species, but also for terrestrial wind-dispersed plants. It is crucial to investigate the role of watercourses in the dispersal of the knotweed hybrid complex (Fallopia × bohemica) due to its frequent occurrence on riverbanks and production of fertile achenes. For this purpose, we experimentally studied buoyancy and germinability of F. × bohemica achenes in stirred water, over 28 d. We also measured the long-term survival and growth of seedlings according to exposure time to water. After nearly 2 d in the water, 50% of achenes were still afloat. After 3 d, germination occurred in water and the seedlings also floated. Moreover, the exposure of achenes to water, for however long, significantly favoured their germination rate, without affecting seedling survival, compared to a direct planting in soil. Furthermore, a maximum seedling dry mass was reached following exposure to water for 277 h (11.5 d), surpassing significantly the dry mass of seedlings planted directly in soil. Water exposure strongly favours achene germination and seedling survival. Our results demonstrate a high potential for the seeds and seedlings of Fallopia to be dispersed successfully by water.

EFFECT OF SEED PRIMING ON INFECTION WITH WHITE TIP NEMATODE (Aphelenchoides besseyi), SEED-BORNE FUNGI, RICE YIELD, AND YIELD COMPONENTS IN EGYPT.

Rice is the second staple food crop after wheat in Egypt. White tip disease of rice leaves induced by the rice leaf nematode, Aphelenchoides besseyi (Christie, 1942), is widespread nearly in all rice ecosystems all over the world, causing remarkable yield reduction to susceptible cultivars. The losses reach to 47% in Egyptian rice Reiho cultivar. Rice seeds are known as the main source of the disease. The present study was conducted to evaluate the effect of seed priming on white tip nematode infection in rice and seed-borne fungi at different plant growth stages. Severely-infected Reiho rice seeds were primed for 48 hr in solutions of NaCl, CaCl2, Na2CO3, MgSO4, CuSO4 and micronized sulfur, separately or in mixtures of two salts except for the sulfur treatment. The primed seeds and the corresponding control non-primed counterparts were then rinsed for three times using tap water and incubated at 30oC to asses the germination percentage, which ranged between 96 to 100% with no significant difference between the primed and non-primed seed treatments. In the lab testing, the maximum seedling vigor index and root / shoot ratio were obtained using seedlings raised from seeds primed with 5 g/L solutions of sulfur (80%WP) followed by sulfur + CaCl2, NaCl and CuSO4. At nursery level, root/shoot ratio increased with all primed seed treatments except with those treated with NaCl solution. Two field experiments were conducted during the 2007and 2008 rice growing seasons. All seed priming treatments significantly enhanced most of the agronomic traits and increased yield in comparison with the non-primed infected or healthy seeds. Soaking in sulfur solution at the concentration of 5g/L and its combinations with the other salts at half dose of each gave the highest mortality of white tip nematode, lowest percentage of white tip infection, and least disease severity. Sulfur and NaCl is then proved to be the most effective priming mixture that can reduce white tip nematode infection. For seed-borne fungi, the treatment with CaCl2 alone or in its all combinations has positive effects in elimination of the Fusarium Moniliforme, Helminthosporium oryzae and Alternaria padwickii in comparison with the water treatment control. CaCl2 completely eradiated F. moniliforme. Seed treatment with mixtures of salts reduced the fungal growth more than did one salt alone. Generally, all seeds primed with salts showed lower levels of infection with F. moniliforme comparing with the control. The treatment with CuSO4 solution at 1.5g/L gave complete protection from seed-borne fungi

상승된 온도 조건에서 물달개비(Monochoria vaginalis)와 올챙이고랭이(Scirpus juncoides)의 출아 및 초기생장 예측

일년생 잡초인 물달개비 및 올챙이고랭이의 출아와 초기생장을 예측하기 위한 모델 구축을 위하여 온도조건을 달리한 식물생장상에서 포트실험을 수행하였다. 이들 잡초의 출아 및 초기생장과 유효적산온도와의 관계를 비선형회귀로 분석한 결과 온도조건에 상관없이 각각 Gompertz 모델 및 logistic 모델로 설명이 잘 되었다. 물달개비 및 올챙이고랭이의 최대 출아율의 50%에 필요한 유효적산온도는 각각 69.3 및 <TEX>$94.8^{\circ}C$</TEX>이었으며, 4엽기에 이르는데 필요한 유효 적산온도는 각각 247 및 <TEX>$234^{\circ}C$</TEX>이었다. 본 연구에서 개발된 모델로 분석한 결과 평균 기온이 <TEX>$3^{\circ}C$</TEX> 상승하게 되면 이들 잡초의 50% 출아는 물달개비의 경우 1일, 올챙이고랭이의 경우는 2일 빨라지고, 4엽기에 다 다르는 날짜는 이들 잡초 모두 3일이 빨라질 것으로 예측되었다. 따라서 온도상승조건에서 물달개비 및 올챙이고랭이를 효과적으로 방제하기 위해서는 현재의 처리시기보다 약 2-3일 빨라져야 할 것으로 예상된다. This experiment was conducted to investigate seedling emergence and early growth of Monochoria vaginalis and Scirpus juncoides in the controlled-environment chamber maintained at different temperatures. Non-linear regression analyses of observed data against effective accumulated temperature (EAT) with the Gompertz and logistic models showed that the Gompertz and logistic models worked well in describing seedling emergence and early growth of both weed species, respectively, regardless of temperature. EATs required for 50% of the maximum seedling emergence and the maximum leaf number of M. vaginalis were estimated to be 69.3 and <TEX>$131^{\circ}C$</TEX>, respectively, while those of S. juncoides were 94.8 and <TEX>$137^{\circ}C$</TEX>, respectively. Models developed in this study thus were used to predict seedling emergence and early growth under elevated temperature condition. If rotary tillage with water is made on 27 May under <TEX>$+3^{\circ}C$</TEX> elevated temperature condition, dates for 50% of the maximum seedling emergence and 4 leaf stage were predicted to be 1 June and 15 June for M. vaginalis and 3 June and 14 June for S. juncoides, respectively. As compared with current temperature, these dates are 1-2 days earlier for the seedling emergence and 3 days earlier for the early growth, suggesting that earlier application of herbicides is required for effective control of M. vaginalis and S. juncoides under elevated temperature condition in the future.