Response of wheat to levels of zinc and potash in calcareous soil

Summary A field experiment was conducted at Agricultural Research Institute, Dholi during Rabi 1976–77 in sandy loam soil to study the interaction between zinc and potash in wheat. Zinc and potash were applied to the soil in the form of ZnSO₄ and KCl respectively. Interaction between zinc and potash was found significant. Both the levels of zinc sulphate 12.5 kg/ha and 25 kg/ha being at par produced significantly higher grain yield over control. There was significant increase in grain yield with application of 40 kg and 80 K₂O/ha over control. Potash at the rate of 120 kg in combination with 25 kg Zinc sulphate/ha decreased the yield.     

THE INFLUENCE OF PLANTING DATE AND MANURING ON THE INCIDENCE OF VIRUS DISEASES IN POTATO CROPS

Field experiments with Majestic potatoes were made over six years at Rothamsted to test the effects of varying date of planting and manuring on the yield of tubers and the incidence of the aphid-transmitted leaf roll and Y (rugose mosaic) viruses. Yield was increased by early planting, and by all the manures, especially dung. Early planting also usually increased the incidence of virus disease. Different manures had different effects on disease incidence; the average results from all comparisons showed the largest increase in incidence of both viruses from the use of dung; sulphate of ammonia increased the incidence of leaf roll, and muriate of potash that of rugose mosaic. Counts in two years showed that aphid populations were highest on the earlier planted potatoes, and were increased by dung, sulphate of ammonia and superphosphate, but were reduced by muriate of potash.     

Biomass Yield of Naturalized Populations and Cultivars of Reed Canary Grass

Reed canary grass is a widely adapted temperate grass with a circumglobal distribution in the northern hemisphere. Because it has relatively high biomass yields under relatively infrequent harvest systems, this species is receiving increasing attention as a bioenergy feedstock. The objective of this study was to conduct a comparative biomass yield evaluation of reed canary grass accessions from a wide range of habitats in the north central and northeastern USA. Eight cultivars and 72 accessions were evaluated for biomass yield over 2 years at five locations in Iowa, New York, and Wisconsin. Accessions produced, on average, 6.7% higher biomass yield than the cultivars. Cultivars ranked from 50th to 77th in biomass yield out of a total of 80 cultivars and accessions. Genetic expression for biomass yield was highly consistent across locations and years. Accessions from southern and western collection sites tended to have the highest biomass yield. Reed canary grass populations in rural landscapes of the central and northeastern USA have value for increasing biomass yield potential of this bioenergy feedstock candidate species. The high biomass yield of many of these populations, combined with the large amount of genetic variability among these populations, offers potential for both short-term gains by selecting superior accessions and long-term gains by selection and breeding.     

Atmospheric impact of bioenergy based on perennial crop (reed canary grass,Phalaris arundinaceae,L.) cultivation on a drained boreal organic soil

Marginal organic soils, abundant in the boreal region, are being increasingly used for bioenergy crop cultivation. Using long‐term field experimental data on greenhouse gas (GHG) balance from a perennial bioenergy crop [reed canary grass (RCG), Phalaris arundinaceae L.] cultivated on a drained organic soil as an example, we show here for the first time that, with a proper cultivation and land‐use practice, environmentally sound bioenergy production is possible on these problematic soil types. We performed a life cycle assessment (LCA) for RCG on this organic soil. We found that, on an average, this system produces 40% less CO₂‐equivalents per MWh of energy in comparison with a conventional energy source such as coal. Climatic conditions regulating the RCG carbon exchange processes have a high impact on the benefits from this bioenergy production system. Under appropriate hydrological conditions, this system can even be carbon‐negative. An LCA sensitivity analysis revealed that net ecosystem CO₂ exchange and crop yield are the major LCA components, while non‐CO₂ GHG emissions and costs associated with crop production are the minor ones. Net bioenergy GHG emissions resulting from restricted net CO₂ uptake and low crop yields, due to climatic and moisture stress during dry years, were comparable with coal emissions. However, net bioenergy emissions during wet years with high net uptake and crop yield were only a third of the coal emissions. As long‐term experimental data on GHG balance of bioenergy production are scarce, scientific data stemming from field experiments are needed in shaping renewable energy source policies.     

Dry rot of potato [Fusarium caeruleum (Lib.) Sacc.]. Investigation on the sources and time of infection

Inoculation with soil samples proved that the fungus causing dry rot is frequently present in field soils in Cheshire and in soil adhering to imported seed tubers. The fungus was viable in soils having a wide range of p H values and in fields which had not grown potatoes for 5-6 years. Other sources of infection include lofts, used sacks, seed boxes, diseased tubers, and knives used for cutting seed potatoes.
Bruised tubers stored in heavily contaminated boxes developed much dry rot; far less disease occurred in unbruised tubers. In boxes containing own-saved seed, healthy tubers in contact with diseased ones remained sound. Bruised tubers in contact with, or contaminated by, diseased tubers contracted dry rot. Cutting seed with a contaminated knife increased the disease seven-fold.
Inoculation of tubers attached to the parent plant showed that little or no infection occurred before lifting. In field trials severe dry rot developed in several varieties 6-8 weeks after lifting.
The results are discussed in relation to seed treatment.     

Reed Canary Grass (Phalaris arundinacea) as a Biological Model in the Study of Plant Invasions

Invasive species pose a serious threat to native plant communities and are an important contributor to loss of biodiversity. In the case of Phalaris arundinacea, L. (Poaceae), reed canary grass, a cool-season, long-lived perennial plant native to Eurasia and North America, nonnative agronomically important genotypes were introduced to North America for numerous uses such as forage and soil stabilization. Following repeated introductions, reed canary grass became an aggressive invader that takes over natural wet prairies, stream-banks and wetlands. Reed canary grass can outcompete native plant species, resulting in monospecific stands with concomitant loss of plant and insect diversity and ultimately to alteration in ecosystem function. Abiotic factors such as disturbance, changes in hydrological regime, and particularly nutrient runoff to wetlands can enhance reed canary grass establishment and vegetative spread. In addition, the species' capacity for early season growth, rapid vegetative spread, high stem elongation potential, wide physiological tolerance, and high architectural plasticity make the species highly aggressive under a wide range of ecological conditions. The change in life-history and environmental conditions responsible for the enhanced aggressiveness observed between native and invasive genotypes are not yet understood. Hence, reed canary grass provides an ideal study system to test a number of ecological and genetic hypotheses to explain why some plant species become extremely aggressive when transported into a new geographical area. To date, genetic studies have found that invasive populations have high genetic diversity and that genotypes differ in their phenotypic plasticity and response to ecological conditions, which may contribute to their invasion success. Finally comparative studies currently underway on European native and American invasive genotypes of reed canary grass should shed light on the mechanisms responsible for reed canary grass's aggressiveness and should provide an experimental protocol to test ecological and genetic hypotheses about what makes a species invasive.     

Bioherbicidal activity of allelopathic bacteria against weeds associated with wheat and their effects on growth of wheat under axenic conditions

Allelopathic bacteria found to selectively inhibit weeds but not wheat in our earlier study were selected to evaluate their impact on three weeds and wheat under axenic conditions. Inoculated seeds of each species were sown in sand jars for 25 days. Results indicated that the applied strains variably inhibited germination of wild oat, little seed canary grass and broad leaved dock from 15.2 to 63.3, 18.5 to 58.7 and 18.4 to 60.5% and dry matter from 12.4 to 65, 22.8 to 81.4 and 21.7 to 71.3% than their controls, respectively. These effects were also evident in other growth parameters. Growth of wheat was significantly improved by four strains while others caused non-significant effects. Selectivity of these strains was also reflected in differential root colonization ability. These strains were characterized for various microbial and biochemical parameters. These strains may further be evaluated for their bioherbicidal activity under natural conditions.     

Yield losses in barley, wheat and potatoes associated with field populations of'large form' Longidorus leptocephalus

Three field experiments made during 1975-77, in North and South Yorkshire, investigated the influence of 'large form' Longidorus leptocephalus upon the yield of spring barley, winter wheat and second early potatoes.
Longidorus populations ranged from undetectable levels to 2375/litre soil. At one site estimates of nematode numbers were made twice, and gave a close agreement between the ranking order of plots. Significant negative correlations between numbers of L. leptocephalus and yield suggested that this nematode impaired the yield of these crops. For each 200 LongidoruslX of soil the estimated reductions in yield were 0–25 t/ha of barley, 0–13 t/ha of wheat and 0–55 t/ha of potatoes.     

Yield, mushroom size and time to production of Pleurotus cornucopiae (oyster mushroom) grown on switch grass substrate spawned and supplemented at various rates

To find a cost effective alternative substrate, Pleurotus cornucopiae 608 (yellow basidiomata) was grown on: (1) chopped, pasteurized switch grass (Panicum virgatum, 99%) with 1% ground limestone and (2) a mixture of pasteurized cottonseed hulls (75% dry wt.), 24% chopped wheat straw, and 1% ground limestone (all ingredients wt./wt.). The substrates were spawned at various levels (2.5%, 3.75% or 5% wet wt., crop I) and non-supplemented or supplemented with commercial delayed release nutrient (Campbell's S-41) at various levels (0%, 1.5%, 3%, 4.5%, 6%, 7.5% and 9% dry wt., crop II). Maximum yield (weight of fresh mushrooms harvested at maturity) was obtained on cottonseed hull/wheat straw substrate at a 3.75-5% spawn level and 6% S-41 supplement. On switch grass substrate, increasing spawn levels and supplement levels stimulated yields in a linear fashion. However, maximum yields were only 46% or less for those of similar treatments on cottonseed hull/wheat straw substrate. Yields were three times higher on switch grass that was harvested after the grass had senesced (winter; beige color) compared to material that was harvested when the grass was green (summer; time of flowering). Additional physical processing of the material, such as milling, may improve yield potential of this material.     

Land use of drained peatlands: Greenhouse gas fluxes,plant production,and economics

Drained peatlands are hotspots for greenhouse gas (GHG) emissions, which could be mitigated by rewetting and land use change. We performed an ecological/economic analysis of rewetting drained fertile peatlands in a hemiboreal climate using different land use strategies over 80 years. Vegetation, soil processes, and total GHG emissions were modeled using the CoupModel for four scenarios: (1) business as usual—Norway spruce with average soil water table of ?40 cm; (2) willow with groundwater at ?20 cm; (3) reed canary grass with groundwater at ?10 cm; and (4) a fully rewetted peatland. The predictions were based on previous model calibrations with several high‐resolution datasets consisting of water, heat, carbon, and nitrogen cycling. Spruce growth was calibrated by tree‐ring data that extended the time period covered. The GHG balance of four scenarios, including vegetation and soil, were 4.7, 7.1, 9.1, and 6.2 Mg CO₂eq ha^?1 year^?1, respectively. The total soil emissions (including litter and peat respiration CO₂ + N₂O + CH₄) were 33.1, 19.3, 15.3, and 11.0 Mg CO₂eq ha^?1 year^?1, respectively, of which the peat loss contributed 35%, 24%, and 7% of the soil emissions for the three drained scenarios, respectively. No peat was lost for the wet peatland. It was also found that draining increases vegetation growth, but not as drastically as peat respiration does. The cost–benefit analysis (CBA) is sensitive to time frame, discount rate, and carbon price. Our results indicate that the net benefit was greater with a somewhat higher soil water table and when the peatland was vegetated with willow and reed canary grass (Scenarios 2 and 3). We conclude that saving peat and avoiding methane release using fairly wet conditions can significantly reduce GHG emissions, and that this strategy should be considered for land use planning and policy‐making.     

Effects of nutrients and shade on tree‐grass interactions in an East African savanna

Abstract. Savanna trees have a multitude of positive and negative effects on understorey grass production, but little is known about how these effects interact. We report on a fertilization and shading experiment carried out in a Tanzanian tropical dry savanna around Acacia tortilis trees. In two years of study there was no difference in grass production under tree canopies or in open grassland. Fertilization, however, indicate that trees do affect the nutrient limitation of the grass layer with an N‐limited system in open grassland to a P‐limited system under the trees. The N:P ratios of grass gave a reliable indication of the nature of nutrient limitation, but only when assessed at the end of the wet season. Mid‐wet season nutrient concentrations of grasses were higher under than outside the tree canopy, suggesting that factors other than nutrients limit grass production. A shading experiment indicated that light may be such a limiting factor during the wet season when water and nutrients are sufficiently available. However, in the dry season when water is scarce, the effect of shade on plant production became positive. We conclude that whether trees increase or decrease production of the herbaceous layer depends on how positive effects (increased soil fertility) and negative effects (shade and soil water availability) interact and that these interactions may significantly change between wet and dry seasons.     

Water relationships and incorporation of C assimilates in tubers of potato plants differing in potassium nutrition

Potato (Solanum tuberosum L. cv Saturna) plants were grown in pots with varying supplies of K fertilizer (1.25, 5, and 10 grams K₂O per 12 kilograms soil). Four weeks after midflower, plants were supplied with ¹⁴CO₂ for 12 hours and osmotic and water potential in tubers were determined. Assimilation of ¹⁴CO₂ increased from 504 (K₁) to 1860 (K₅) and 1922 kilobecquerels per plant per 12 hours (K₁₀). In all treatments, about half of the ¹⁴C was translocated to the tubers within 12 hours, although calculated turgor pressure in tubers which could be considered as a potential counter-pressure to phloem unloading increased from +5.3 (K₁) to +5.9 (K₅) and +6.0 bars (K₁₀), respectively. Incorporation of ¹⁴C per gram tuber dry weight as well as per gram tuber starch was significantly higher in K₅ than in K₁ and slightly increased even further in the K₁₀ treatment, where tuber pressure sap contained the highest K concentration (179 millimolar K).     

赣江流域土地利用方式对河流水质的影响

赣江是鄱阳湖的最大支流,是鄱阳湖水污染物的主要来源,查明流域土地利用方式对赣江水质的影响和鄱阳湖的水环境保护具有重要意义。基于2012年对赣江7个主要支流NH+4-N、TP、CODMn和DO浓度的每月测定结果,通过不同空间尺度和土地类型等级划分,利用相关分析和冗余分析研究土地利用方式对赣江流域河流水质的影响。研究结果表明,子流域的土地利用方式对TP的影响大于缓冲区;对CODMn的影响在丰水期大于缓冲区,在枯水期小于缓冲区;对NH+4-N的影响在丰水期与缓冲区接近,在枯水期小于缓冲区;DO受土地利用方式的影响较小。水田中的丘陵水田是赣江水体TP和丰水期CODMn的主要来源;平原水田是枯水期CODMn的主要来源。居民建设用地中的城镇用地是赣江水体TP、NH+4-N和丰水期CODMn的主要来源,农村用地是CODMn的主要来源。水域中的水库坑塘是赣江水体TP和丰水期NH+4-N、CODMn的主要来源。     

Effects of rotation length, fungicide treatment of seed tubers and nematicide on diseases and the quality of potato tubers

In 1982 – 88, potatoes were grown in 2-, 4- and 6-course rotations with spring barley on a field infested with Globodera rostochiensis. Severity of stem canker and black scurf increased with increasing frequency of previous potato crops, and seed tuber treatment with tolclofos-methyl became less effective in controlling diseases. This suggested that previous crops had increased the amounts of soil-borne inoculum of Rhizoctonia solani. Oxamyl soil treatment increased stem canker in one year and decreased black scurf in four years. Seed tuber treatment with imazalil or prochloraz decreased stem base infection by Polyscytalum pustulans and skin spot and silver scurf on tubers. Black dot was prevalent on tubers in all years and was not affected by seed tuber treatment or previous cropping. Oxamyl increased black dot and common scab in five years and decreased % tuber dry matter in six years. Cysts of G. rostochiensis were found attached to Désirée but not to Maris Piper tubers in August. At harvest tubers of both cultivars were affected by superficial pitting and its severity was related to soil populations of G. rostochiensis at planting. This damage was controlled by oxamyl. It is suggested that the pitting developed from holes made in the tuber skin at larval invasion. In 1989, Désirée seed tubers and healthy mini tubers were planted in all plots and severity of stem canker and black scurf increased with increasing proximity of previous potato crops and with the number of previous crops. Black dot on stems and tubers was not affected by previous cropping but was much less severe in a plot that had not grown potatoes during the seven years of the experiment. The severity of common scab generally decreased as the number of preceding potato crops increased.     

Development of black dot disease (Colletotrichum coccodes (Wallr.) Hughes) and its effects on the growth and yield of potato plants

Seed tubers of cvs Désirée and Pentland Crown with different severities of black dot were planted in 1988 and 1989 at Rothamsted in fields in 4– or 7-course rotations, respectively. Tubers treated with prochloraz (1988) or imazalil (1989) were planted in some plots, and in others Colletotrichum coccodes inoculum was added to the soil at planting. In further experiments at Mepal, Cambridgeshire in 1989 and 1990 and at Rothamsted in 1990 on sites where potatoes had not been grown for more than 15 years, large amounts of inoculum were added to the soil around disease-free seed tubers of two (1989) or three (1990) cultivars at planting. In all experiments plants were sampled during the season and the effects of treatments on disease development, growth and yield were recorded. Disease on roots, stem bases and tubers was found early in the season and was more severe on Désirée than on Pentland Crown plants from fields in 4– or 7-course rotations. Severity increased throughout the season and with increasing amounts of disease on the seed tubers, especially with Desiree. Disease was also found on plants from disease-free tubers and was more severe in 1988 than 1989. At harvest, black dot on tubers was significantly more severe from severely affected than from disease-free seed, and was most severe where inoculum, especially large amounts, had been added at planting. Fungicide treatment decreased disease early in the season but had no effect on tuber infection at harvest. In 1989 the weight loss of seed tubers during sprouting increased with increasing amounts of black dot, but the disease had little effect on plant size through the season. At harvest the yield of ware tubers (>50 mm) decreased with severe disease but total tuber yields were not significantly affected. However, at harvest in 1988 severely affected seed yielded significantly less than healthy seed. Plants grown from mini-tubers were free from disease on sites where potatoes had not been grown for at least 15 years. Inoculum applied at planting caused severe disease on all cultivars in both years, whereas disease was slight on uninoculated plants. Inoculated plants senesced early at Mepal in 1990, but there were no significant differences in total tuber yield in any experiment. However, yields of ware tubers (>50 mm) were sometimes decreased and the total tuber number per plant increased.     

The influence of sewage sludge on the content of heavy metals in potatoes and on tuber yield

Summary A small plot field experiment with two types of sewage sludge, one poor and one rich in heavy metals, applied in moderate and heavy quantities, and compared with NPK-fertilizer, was carried out 1973 and 1974, in potatoes. The chemical composition of the NPK-fertilizer and the sludges, and the amounts applied are found in Tables 1 and 2.The sludge increased the content of total Cd, Ni and Pb and the content of readily soluble Cu and Zn in the soil. The increase was greatest for Cu and Zn, and was more pronounced the second than the first year (Table 3). The small quantities of heavy metals in NPK-fertilizer did not influence the soil analytical values.Digested sludge increased the yield of tubers significantly, but based on the amounts of nutrients applied, NPK-fertilizer was much more efficient than sludge (Table 4). It is suggested that low utilization of N, or lack of K, is mainly responsible for the lower efficiency of sludge. Toxicity in the plants due to sludge was not observed.Application of 40–80 tons/ha of sludge dry matter, rich in heavy metals, increased considerably the concentration of Cu and Zn in the tubers, whereas 10–20 tons/ha did not influence the concentration (Table 6). The content of Hg, Ni and Pb in the tubers was very little influenced by sludge application. The Cd-concentration was mostly below 0.05 mg/kg of fresh tubers, and the analytical technique was not accurate enough to detect possible influence of increasing amounts of Cd in sludge. Generally, less than 0.5% of the heavy metals applied was accumulated in the tubers. The concentration of heavy metals in fresh tubers was in all cases below suggested maximum tolerable values for food. re]19760203     

Cultivation of a perennial grass for bioenergy on a boreal organic soil – carbon sink or source?

The area under the cultivation of perennial bioenergy crops on organic soils in the northern countries is fast increasing. To understand the impact of reed canary grass (RCG, Phalaris arundinaceae L.) cultivation on the carbon dioxide (CO₂) balance of an organic soil, net ecosystem CO₂ exchange (NEE) was measured for four years in a RCG cultivated cutover peatland in eastern Finland using the eddy covariance technique. There were striking differences among the years in the annual precipitation. The annual precipitation was higher during 2004 and 2007 and lower during 2005 and 2006 than the 1971–2000 regional mean. During wet growing seasons, moderate temperatures, high surface soil moisture and low evaporative demand favoured high CO₂ uptake. During dry seasons, owing to soil moisture and atmospheric stress, photosynthetic activity was severely restricted. The CO₂ uptake [gross primary productivity (GPP)] was positively correlated with soil moisture, air temperature and inversely with vapour pressure deficit. Total ecosystem respiration (TER) increased with increasing soil temperature but decreased with increasing soil moisture. The relative responses of GPP and TER to moisture stress were different. While changes in TER for a given change in soil moisture were moderate, variations in GPP were drastic. Also, the seasonal variations in TER were not as conspicuous as those in GPP implying that GPP is the primary regulator of the interannual variability in NEE in this ecosystem. The ecosystem accumulated a total of 398 g C m^?2 from the beginning of 2004 until the end of 2007. It retained some carbon during a wet year such as 2004 even after accounting for the loss of carbon in the form of harvested biomass. Based on this CO₂ balance analysis, RCG cultivation is found to be a promising after‐use option on an organic soil.     

Tree stem bases are sources of CH4 and N2O in a tropical forest on upland soil during the dry to wet season transition

Tropical forests on upland soils are assumed to be a methane (CH₄) sink and a weak source of nitrous oxide (N₂O), but studies of wetland forests have demonstrated that tree stems can be a substantial source of CH₄, and recent evidence from temperate woodlands suggests that tree stems can also emit N₂O. Here, we measured CH₄ and N₂O fluxes from the soil and from tree stems in a semi‐evergreen tropical forest on upland soil. To examine the influence of seasonality, soil abiotic conditions and substrate availability (litter inputs) on trace greenhouse gas (GHG) fluxes, we conducted our study during the transition from the dry to the wet season in a long‐term litter manipulation experiment in Panama, Central America. Trace GHG fluxes were measured from individual stem bases of two common tree species and from soils beneath the same trees. Soil CH₄ fluxes varied from uptake in the dry season to minor emissions in the wet season. Soil N₂O fluxes were negligible during the dry season but increased markedly after the start of the wet season. By contrast, tree stem bases emitted CH₄ and N₂O throughout the study. Although we observed no clear effect of litter manipulation on trace GHG fluxes, tree species and litter treatments interacted to influence CH₄ fluxes from stems and N₂O fluxes from stems and soil, indicating complex relationships between tree species traits and decomposition processes that can influence trace GHG dynamics. Collectively, our results show that tropical trees can act as conduits for trace GHGs that most likely originate from deeper soil horizons, even when they are growing on upland soils. Coupled with the finding that the soils may be a weaker sink for CH₄ than previously thought, our research highlights the need to reappraise trace gas budgets in tropical forests.     

Potential local adaptation in populations of invasive reed canary grass (Phalaris arundinacea) across an urbanization gradient

Urban stressors represent strong selective gradients that can elicit evolutionary change, especially in non‐native species that may harbor substantial within‐population variability. To test whether urban stressors drive phenotypic differentiation and influence local adaptation, we compared stress responses of populations of a ubiquitous invader, reed canary grass (Phalaris arundinacea). Specifically, we quantified responses to salt, copper, and zinc additions by reed canary grass collected from four populations spanning an urbanization gradient (natural, rural, moderate urban, and intense urban). We measured ten phenotypic traits and trait plasticities, because reed canary grass is known to be highly plastic and because plasticity may enhance invasion success. We tested the following hypotheses: (a) Source populations vary systematically in their stress response, with the intense urban population least sensitive and the natural population most sensitive, and (b) plastic responses are adaptive under stressful conditions. We found clear trait variation among populations, with the greatest divergence in traits and trait plasticities between the natural and intense urban populations. The intense urban population showed stress tolerator characteristics for resource acquisition traits including leaf dry matter content and specific root length. Trait plasticity varied among populations for over half the traits measured, highlighting that plasticity differences were as common as trait differences. Plasticity in root mass ratio and specific root length were adaptive in some contexts, suggesting that natural selection by anthropogenic stressors may have contributed to root trait differences. Reed canary grass populations in highly urbanized wetlands may therefore be evolving enhanced tolerance to urban stressors, suggesting a mechanism by which invasive species may proliferate across urban wetland systems generally.