Factors affecting germination and stand establishment ofphyllanthus Amarus (Euphorbiaceae)

Interest inPhyllanthus amarus (Euphorbiaceae) has been generated by reports of antiviral activity and wide usage in traditional medicine. Attempts at cultivation resulted in poor stands. The objectives of these studies were to determine the effects of light, storage temperature, age of seeds, time ofdehiscence, and a scarification procedure on the germination ofP. amarus. Seeds ofP. amarus require light to germinate, and thus should not be covered at sowing. Freezing did not significantly affect the germination of dry seeds compared to seeds stored at ambient room temperature or higher, but storage at 10°C was deleterious. Percent germination was typically less than 50% and significantly decreased with time. Germination of freshly harvested seeds was slower than older seeds. Seeds from the first capsules to dehisce had a higher percent germination. A scarification procedure rendered seeds inviable. These results helped explain poor stands seen infield plots. In a previously planted plot, the re-established stand by natural reseeding was equivalent to that following intentional reseeding procedures.     

The parasitism of Striga hermonthica Benth. on Sorghum spp. under irrigation: I. Preliminary results and the effect of heavy and light irrigation on Striga attack

Investigations were carried out at the Gezira Research Farm in the Anglo-Egyptian Sudan. The greater majority of the seeds of Striga hermonthica can only be germinated by excretions from roots of certain plants not all of which can act as hosts for this parasite. Unless it becomes attached to a host plant, the Striga seedling dies. The growing of those plants whose roots can stimulate the germination of Striga seed but cannot be parasitized by it, may be a means of ridding infested land of this parasite. Green ovaries picked from flowering plants produce viable seeds if left to dry. Sorghum is sown in the field during the rainy season, viz. June to October: the earlier the sowing date within this period the greater is the Striga attack. In the field Striga seeds are distributed in the soil to a depth of at least 15 in. When Striga seeds are evenly distributed through the soil, the number of Striga seedlings attached to a sorghum root is proportional to the root's development. Size of sorghum seed has no effect on the root size of a sorghum plant and consequently no effect on the degree of parasitism. The effect of severe Striga attack on the sorghum plant is to produce a reduction of about 60% in leaf and root weight. No reduction of Striga attack is obtained when various micro-elements are coated on sorghum seeds before sowing. Field and laboratory experiments show that light irrigation of the sorghum crop during the normal sowing period increases the Striga attack and heavy irrigation decreases it. This result was not obtained in laboratory experiments when sorghum was sown out of season. Striga attack is lessened when conditions favouring growth of the sorghum crop are improved.     

Fungicide seed treatments increase growth of perennial ryegrass

Field, laboratory and glasshouse experiments were carried out to measure effects of seed treatments with captan or thiram on growth of perennial ryegrass (Lolium perenne L.). Field-sown captan- or thiram-treated seed gave twice as many seedlings as untreated seed. Spaced plants growing from fungicide-treated seed produced almost 6 times more dry matter 16 weeks after sowing than those from untreated seed. This effect, though diminishing with time, was still apparent more than a year after sowing. Fungicides in sterile agar growth medium were phytotoxic to seedlings at concentrations of 10μg/ml and greater. Seedlings grown from treated seeds sown from 5 to 15 mm away from developing colonies of the virulent seedling pathogenFusarium oxysporum Schlecht. were more than 4 times larger than those grown from untreated seeds. Captan-treated seed sown into pots containing field soil produced more and larger seedlings than untreated seed. Methyl bromide fumigation of the same soil also increased both number and size of seedlings. Fungicidal, rather than direct chemical effects, at early stages of seedling growth, account for increased growth of plants from fungicide-treated seed.     

农田秸秆覆盖对冬小麦水氮效应的影响

通过田间试验研究了杨凌红油土农田秸秆覆盖条件下冬小麦的水氮效应.结果表明,秸秆覆盖使土壤水分状况明显改善,从而使补充灌水的效果相应减小,氮肥的作用更加突出;无覆盖条件下,水氮交互效应均为负值,而秸秆覆盖时水氮有正的交互作用.旱地秸秆覆盖条件下更应重视养分的投入.无秸秆覆盖条件下小麦取得高产的基础是良好的土壤底墒和充足的氮肥.秸秆覆盖使小麦达到最高产量所需要的灌水量降低,灌水时期后延.不论有无秸秆覆盖,拔节期灌水对冬小麦籽粒产量没有显著影响.     

Assessing seed priming,sowing date,and mulch film to improve the germination and survival of direct‐sown Miscanthus sinensis in the United Kingdom

Direct sowing of Miscanthus seed could lower crop establishment costs, and increase the rate of grower uptake and biomass supply for the emerging bio‐economy. A replicated field trial was conducted at two contrasting UK sites: Aberystwyth (ABR) in mid‐Wales and Blankney (BLK) in Lincolnshire. These sites encompass the west–east meteorological gradient in the United Kingdom where the growing season at ABR is cooler and wetter while BLK is warmer and drier. Primed and unprimed Miscanthus sinensis seeds were sown directly onto the soil surface with and without a clear biodegradable mulch film, at nine dates interspersed from May to October. Average daily mean soil surface temperatures measured over the first 2 months after sowing under the mulch film were higher than control plots (2.7°C ABR and 4.2°C BLK). At both sites, the film covering also affected soil volumetric moisture relative to uncovered control plots (?3% ABR and 8% BLK), demonstrating the negative impact of mulch film when sowing on dry soil. Over nine sowings, seed germination at ABR under film varied between ?28% and +18% of germination under control conditions. Seedlings from the first three sowings at both sites under film had sufficient physiological maturity to survive the first winter period. At BLK, mulch film significantly increased tiller count and height in both the first and second years after sowing. At ABR, where temperatures were lower, film covering significantly increased tiller height but not count. Water priming had no significant effect on seed viability or germination in the field tests. Base temperatures for germination of primed and unprimed seeds on a thermal gradient plate were 7.0°C and 5.7°C, respectively, with a ± 1.7°C confidence interval. Based on our results for M. sinensis in the United Kingdom, we recommend the sowing of unprimed seed in May under film and only when the soil is moist.     

Sowing seasons and drying methods during post-harvest influence the seed vigour of soybean (Glycine max (L.) Merr.)

Experiments were conducted to study the influence of sowing seasons and drying methods on the seed vigour of two spring soybean (Glycine max (L.) Merr.) cultivars. Two cultivars, ‘Huachun18’ and ‘Huachun 14’, were sown in three seasons viz., spring, summer and autumn and the harvested seeds were dried using three different methods. The results showed that soybean sown in spring had a higher number of branches per plant, pods per branch and seed weight, and consequently resulted in higher seed yields than that of soybean sown in autumn or summer seasons. Seeds sown in the autumn season had the lowest values of electrical conductivity during seed imbibitions, higher peroxidase (POD) activity in germinated seedlings and lower contamination by the seed-borne fungi on the MS medium, which indirectly improved the seed vigour, which was followed by summer sown seeds. Seeds sown during the spring season resulted in poor seed vigour. In addition, the effect of drying methods on the seed vigour was also clarified. Seeds that hung for four days before threshing and then air-dried had the poorest seed vigour which was determined by germination, electrical conductivity, POD activity and seed borne fungal growth. There was no difference in seed vigour between other methods, i.e. seeds threshed directly at harvest and then air-dried on a bamboo sifter or concrete floor. These results indicated that autumn sowing soybean and the drying method in which seeds were threshed directly at harvest and then air-dried on a bamboo sifter resulted in higher seed vigour.     

In vitro activity of phyllanthus (Euphorbiaceae) species against the DNA polymerase of hepatitis viruses: Effects of growing environment and inter- and intra-specific differences

Extracts of Phyllanthus amarus (Euphorbiaceae) are known to reduce or eliminate detectable hepatitis B virus surface antigen in humans or surface antigen of woodchuck hepatitis virus in woodchucks. The objectives of the experiments in this paper were to evaluate the in vitro inhibición of viral DNA polymerase (DNAp) among (1) different species of Phyllanthus; (2) within the most promising species; and (3) to evaluate differences in activity that might be correlated with environmental effects. The ultimate goal of our studies is to develop a system for producing high quality plants for large scale extraction. Inhibitory activity varied significantly among species. InP. urinaria there were also significant differences among intraspecific accessions. Accessions ofP. amarus from various locations did not differ significantly. Experiments with one seedlot showed highly significant plant-to-plant differences in anti-viral activity, but clear-cut heritable differences were not established among progeny of the plants at extremes in the distribution. Differences in general soil fertility, soil moisture, pH or Ca generally did not significantly affect inhibición of viral DNAp but temperature differences did. Except for temperature, the detectable environmental effects were generally less than the size of the genetic differences among species.P. amarus was successfully grown as a row crop with inputs of fertilizer and irrigation and showed no loss of activity when compared to samples from the wild. Thus, once an accession of Phyllanthus with potent inhibición of viral DNAp is identified, it can be grown under cultivated conditions for extraction without a loss of activity.     

Vegetative growth and photosynthesis in coffee plants under different watering and fertilization managements in Yunnan,SW China

In a field experiment Coffea arabica L. was subjected to various moisture and fertilizer regimes in Simao, Yunan, SW China. The experimental treatments consisted of eight factorial combinations of two fertilization levels (high and low) and four watering treatments applied in the dry season: application of dry rice straw mulch, drip irrigation, mulching plus drip irrigation on the soil surface, and control (no mulching or irrigation). The growth of the coffee plants was monitored throughout the course of a full year. Two clear growth peaks were detected (one at the beginning and one in the middle of the wet season) in plants subjected to all treatments, and the growth rhythm of coffee plants was not regulated by extrinsic abiotic factors. High fertilization resulted in a significantly higher relative growth rates for both height and length of the branches during the growth peaks than the low fertilization treatment. In the dry season, increasing the soil moisture contents by irrigation and/or mulching enhanced the plants’ gas exchange, but the soil water status had no significant effects on the internal fluorescence parameters of photosystem 2. More fertilized plants had a greater ability to acclimate to high-irradiance environments than the lightly fertilized plants, showing significant lower diurnal photoinhibition, associated with higher energy utilization through photochemistry and energy dissipation through the xanthophyll cycle. Hence the wet season is the optimum period for photosynthetic carbon fixation and vegetative growth of coffee plants. Higher than routinely applied levels of fertilization are required to optimize the coffee plants’ photosynthetic acclimation and growth in the studied environment. Both soil moisture conserving practices tested, mulching and drip irrigation, had significant effects on the growth and photosynthesis of the coffee plants, but the former was more practical than the latter.     

Evaluation of single chemical extractants for the prediction of heavy metal uptake by barley in soils amended with polluted sewage sludge

The main aim of this study was to compare the suitability of three single chemical extractants [EDTA, CaCl₂ and the low-molecular-weight organic acids solution (LMWOAs)] to estimate Cu, Zn and Ni uptake by barley (Hordeum vulgare) from rhizosphere soils, following a single application of a metal salts-spiked sewage sludge. Thirty-six contrasting soils from different parts of Spain were amended with the same dose (15.71 g dry weight kg^-1) of polluted sewage sludge and sown with barley seeds under greenhouse conditions. Eight weeks after sowing, the plants were harvested and Cu, Zn and Ni were analysed in the roots. Heavy metal uptake was then compared with the theoretically available heavy metals in the rhizosphere soils, assessed by the three single chemical extractants. These three extractants alone failed to predict heavy metal uptake, and soil properties were needed to obtain accurate predictions. Thus, none of the methods tested in this study can be used as a universal soil extraction for estimating Cu, Zn and Ni uptake by barley.     

Seed size and recruitment limitation influence seedling establishment in three tallgrass prairie species

A seed size–seed number tradeoff predicts that large numbers of seeds have an establishment advantage under low levels of competition, while large seed size is advantageous under asymmetric competition. Testing these predictions in the context of tallgrass prairie restoration should increase predictability of outcomes of species composition—restoration technique combinations. I conducted field and greenhouse experiments comparing seedling establishment among three tallgrass prairie species with different seed mass-seed number combinations, but with similar mass of seeds sown. Species were prairie dock [Silphium terebinthinaceum, mass = 33.2 + 2.1 mg ( \(\overline{x}\)  + SE, n = 100)], wild quinine (Parthenium integrifolium, mass = 3.1 + 0.3 mg), and smooth blue aster (Symphyotrichum laeve var. laeve, mass = 0.53 + 0.02 mg). Seeds were sown into mowed or tilled plots with shade and mulch treatments in an old field in northeastern Illinois USA, and seeds were sown into containers with or without vegetative cover in a greenhouse. In mowed plots, species with larger numbers of seeds sown had higher seedling densities. In tilled plots, seedling densities of the large-seeded Silphium were reduced less by shade than the small-seeded Parthenium. Symphyotrichum, however, did not respond to treatments as expected based on its seed size. High relative growth rate possibly increased Symphyotrichum seedling establishment in competitive environments. Results of this study demonstrated recruitment limitation when seedlings established into existing vegetation, and suggest that species composition resulting from specific seeding rates during prairie restoration may be more predictable when species are interseeded into existing vegetation, than when seeds are sown into tilled fields.     

Grain zinc, iron and protein concentrations and zinc-efficiency in wild emmer wheat under contrasting irrigation regimes

Micronutrient malnutrition, and particularly deficiency in zinc (Zn) and iron (Fe), afflicts over three billion people worldwide, and nearly half of the world’s cereal-growing area is affected by soil Zn deficiency. Wild emmer wheat [Triticum turgidum ssp. dicoccoides (Körn.) Thell.], the progenitor of domesticated durum wheat and bread wheat, offers a valuable source of economically important genetic diversity including grain mineral concentrations. Twenty two wild emmer wheat accessions, representing a wide range of drought resistance capacity, as well as two durum wheat cultivars were examined under two contrasting irrigation regimes (well-watered control and water-limited), for grain yield, total biomass production and grain Zn, Fe and protein concentrations. The wild emmer accessions exhibited high genetic diversity for yield and grain Zn, Fe and protein concentrations under both irrigation regimes, with a considerable potential for improvement of the cultivated wheat. Grain Zn, Fe and protein concentrations were positively correlated with one another. Although irrigation regime significantly affected ranking of genotypes, a few wild emmer accessions were identified for their advantage over durum wheat, having consistently higher grain Zn (e.g., 125 mg kg^?1), Fe (85 mg kg^?1) and protein (250 g kg^?1) concentrations and high yield capacity. Plants grown from seeds originated from both irrigation regimes were also examined for Zn efficiency (Zn deficiency tolerance) on a Zn-deficient calcareous soil. Zinc efficiency, expressed as the ratio of shoot dry matter production under Zn deficiency to Zn fertilization, showed large genetic variation among the genotypes tested. The source of seeds from maternal plants grown under both irrigation regimes had very little effect on Zn efficiency. Several wild emmer accessions revealed combination of high Zn efficiency and drought stress resistance. The results indicate high genetic potential of wild emmer wheat to improve grain Zn, Fe and protein concentrations, Zn deficiency tolerance and drought resistance in cultivated wheat.     

Effects of germination time on seed morph ratio in a seed-dimorphic species and possible ecological significance

Background and Aims Diaspores of heteromorphic species may germinate at different times due to distinct dormancy-breaking and germination requirements, and this difference can influence life history traits. The primary aim of this study was to determine the effect of germination time of the two seed morphs of Suaeda corniculata subsp. mongolica on life history traits of the offspring.Methods Germinated brown and black seeds were sown on the 20th of each month from April to September in a simulated but near-natural habitat of the species. Phenological and vegetative traits of the maternal plants, and number, size and germination percentage of the offspring were determined.Key Results Germinated seeds sown late in the year produced smaller plants that had a higher proportion of non-dormant brown than dormant black seeds, and these brown seeds were larger than those produced by germinated seeds sown early in the year. The length of the seedling stage for brown seeds was shorter than that for black seeds, and the root/shoot ratio and reproductive allocation of plants from brown seeds were more variable than they were for plants from black seeds. Late-germinating brown seeds produced larger plants than late-germinating black seeds.Conclusions Altering the proportion of the two seed types in response to germination timing can help alleviate the adverse effects of delayed germination. The flexible strategy of a species, such as S. corniculata, that produces different proportions of dimorphic seeds in response to variation in germination timing may favour the maintenance and regeneration of the population in its unpredictable environment.     

黄腐酸拌种对春小麦产量和水分利用效率的影响

在大田研究了黄腐酸拌种对春小麦产量形成和水分利用效率的影响。实验设４个处理：对照（ＣＫ）,播种前种子不处理;ＦＡ处理：播种前用ＦＡ拌种;ＷＭ处理：浇３０ｍｍ底墒水,覆膜;处理ＷＭＦＡ：浇３０ｍｍ底墒水,覆膜,播种前用ＦＡ拌种。２个覆膜处理均在播种后６２ｄ揭膜。同ＣＫ相比,ＦＡ拌种后,根系生长良好,吸收利用了更多的土壤水分,增加了穗重、单穗籽粒重和收获指数,产量和水分利用效率均显著提高。ＷＭ和ＷＭＦ     

Sowing and transplantation of Adonis ramosa (Ranunculaceae) for the establishment of a new population in a seminatural broad-leaved deciduous forest floor

Adonis ramosa (Ranunculaceae) is a plant whose risk of extinction is increasing in Japan. In this study, we show that there is a significant possibility of establishing an A. ramosa population by sowing seeds or transplanting plants in a seminatural broad-leaved deciduous forest floor. Immediately after seed collection in early June, seeds were sown either in pots that were watered periodically or in a deciduous forest floor where the soil surface was prepared. In the following spring, 30–40% of the seeds germinated. Of the one-year-old plants buried at a depth of 2 cm and two-year-old plants buried at a depth of 2 or 8 cm in the fall, 96% sprouted leaves in the following spring. However, 79% of the one-year-old plants buried at a depth of 8 cm sprouted leaves. In spring, the number of leaves, the widths of individual plants, and the heights of the two-year-old plants were greater than those of the one-year-old plants. The dry weights of one- and two-year-old plants in fall after one spring growing season increased by 1.6–2.3 times and by 2.3–5.1 times, respectively, compared to the dry weight at the time of transplanting. Also, the dry weights of the plants transplanted at a depth of 8 cm were higher than those of plants transplanted at a depth of 2 cm for both one- and two-year-old plants. The results suggest that the growth conditions at a depth of 8 cm are more favorable than those at a depth of 2 cm.     

Furanocoumarins in seeds of wild and cultivated parsnip

The furanocoumarin content of ripe seeds of seven cultivars of Pastinaca sativa was compared to that of ripe seeds from a naturalized population in central Illinois. Five furanocoumarins were identified and quantified in the intact seeds. While seeds of wild and cultivated plants contain furanocoumarin components in identical proportions, seeds from wild plants contain almost three times the quantity of furanocoumarins on a dry weight basis as do seeds of cultivars.     

Effect of seed depth on slug damage to winter wheat

In a field experiment drilled at two depths on three dates in autumn 1988, with or without methiocarb pellets broadcast on the soil surface immediately after drilling, 26% of seeds of winter wheat sown at c. 20 mm depth were killed by slugs compared with only 9% of seeds sown at c. 40 mm. The protection from slug damage provided by this additional 20 mm of depth was comparable with that provided by methiocarb pellets. The effects of seed depth and pellet application did not interact and were consistent on all drilling dates. Thus, fewest seeds and seedlings were killed where methiocarb pellets were broadcast on a seed-bed with seeds sown at 40 mm depth. Intermediate damage was recorded where seeds were sown at 40 mm depth without pellets, or where pellets were broadcast on seeds sown at 20 mm depth. Most seeds and seedlings were killed where seeds were sown at 20 mm depth without pellets. Sublethal damage to seedlings was not affected by sowing depth but was reduced where pellets were broadcast immediately after sowing.     

Irrigation and Seed Quality Development in Rapid-cycling Brassica: Seed Germination and Longevity

Irrigation of rapid-cycling brassica (Brassica campestris [rapa]L.)plants either ended 16 or 24 days after pollination (DAP) orcontinued throughout the experiment (control). Seeds were harvestedserially from these plants during their development and maturation.The earlier irrigation to the mother plant ended, the earliermass maturity (end of seed-filling phase) occurred, the lowerthe final seed dry weight, and the more rapid the decline inseed moisture content. The onset of ability to germinate normallyoccurred as early as 12 DAP, when seeds were less than half-filled.The onset of ability to tolerate rapid enforced desiccation(to 10% moisture content) occurred at 16 DAP. Desiccation tolerancedeveloped within most seeds in both populations about 5 d soonerin seeds harvested from plants in which irrigation was stoppedat 16 DAP than in control plants, but maximum desiccation toleranceoccurred at about 28 DAP in all treatments. Survival curves(percentage normal germinationvs.period of storage) of seedshermetically stored at 40 °C with 15% moisture content conformedto negative cumulative normal distributions, and provided acommon estimate of the standard deviation of the frequency distributionof seed deaths in time for seed lots harvested at differenttimes from the three environments (     

Endogenous levels of auxin and tumorigenesis in a Nicotiana amphiploid

Young seedlings of the tumor-prone amphiploid Nicotiana suaveolens X N. langsdorffii were grown aseptically on nutrient medium in a controlled environment chamber. At regular intervals after the seeds had been sown, the incidence of tumor formation was scored and plants were harvested. Indole-3-acetic acid was extracted, purified, and assayed spectrofluorometrically. A close correlation in time between onset of tumor formation and decline in endogenous level of indole-3-acetic acid was demonstrated.     

Isolation, characterization and antioxidative effect of phyllanthin against CCl4-induced toxicity in HepG2 cell line

The present study was an attempt to investigate the hepatoprotective and antioxidative property of Phyllanthus amarus (P. amarus) extract and phyllanthin. Phyllanthin, one of the active lignin present in this plant species was isolated from the aerial parts, by silica gel column chromatography employing gradient elution with hexane-ethyl acetate solvent mixture. It was obtained in high yields (1.23%), compared to reported procedures and the purity was ascertained by HPTLC and reversed-phase HPLC analysis. Characterization of phyllanthin was done by mp, UV-Visible spectrophotometry, elemental analysis, FT-IR, ¹H NMR, ¹³C NMR and mass spectral analysis. Free radical scavenging activity of P. amarus extract and phyllanthin was also examined using DPPH assay. The protective effect of P. amarus extract and phyllanthin was studied on CCl₄-induced toxicity in human hepatoma HepG2 cell line. The results indicated that CCl₄ treatment caused a significant decrease in cell viability. In addition, the toxin treatment initiated lipid peroxidation (LPO), caused leakage of enzymes like alanine transaminase (ALT) and lactate dehydrogenase (LDH) with a significant decrease in glutathione (GSH) levels. It was observed that phyllanthin effectively alleviated the changes induced by CCl₄ in a concentration-dependent manner, with much smaller strengths as compared to P. amarus extract.