Sudangrass Research Articles

Scutellospora alterata, a new gigasporalean species from the semi-arid Caatinga biome in Northeastern Brazil

A new species of Gigasporales (Glomeromycota) was isolated from soils of the semi-arid Caatinga biome in NE Brazil. It produced spores in the rhizospheres of Sorghum sudanense, Zea mays, Panicum maximum, and Helianthus annuus in pot cultures. Spores are triple-walled, roughened, yellow-white to light yellow, and 150–255 μm in diameter. The single germination shield is hyaline, oval to ovoid, and bi-lobed and has the two germ tube initiations (gtis) typical for Scutellospora species. The shields can change shape under light pressure on the cover slide, causing several 'false' lobes to appear that do not bear gtis but inflate from the shield periphery. Molecular analyses of the partial LSU rDNA gene place the fungus in a clade next to Scutellospora calospora, S. dipurpurescens, and S. spinosissima. Further investigations on germ shield morphology showed that several false lobes also form in other Scutellospora species in lactic acid based mountants under pressure on the cover slide. In Racocetraceae more than two 'true' lobes form during spore formation, each potentially bearing one gti.

Effects of Irrigation Water Quality and Nitrogen Rate on the Recovery of 15N Fertilizer by Sorghum in Field Study

The effects of 15N-labeled ammonium nitrate on yield, uptake of nitrogen (N) by sorghum (Sorghum sudanense, Piper), and on N remaining in the soil were studied in a field experiment with different N rates (0, 50, and 100 kg N ha−1) and with two irrigation water qualities, well water (WW) and treated wastewater (TWW). Treated wastewater irrigation increased dry matter and N yield compared to WW. At equal N rates, recovery of 15N-labeled fertilizer by plants increased with TWW irrigation compared to WW (36% versus 23%). Neither fertilizer rate nor water quality had an effect on the 15N-labeled fertilizer remaining in the 0- to 60-cm layer of soil. On average 41% in the TWW treatment (49–33%) and 38% in WW treatment was mostly present in the surface 20-cm layer. Losses of 15N-labeled fertilizer were unaffected by irrigation water quality (35%) and increased with N application rate in TWW (4% versus 31%).

PARÂMETROS COMPORTAMENTAIS DE VACAS DE DESCARTE EM PASTAGENS DE MILHETO OU CAPIM SUDÃO

The objective of this study was to evaluate the behavioral parameters and strategies of displacement and feeding of cull cows grazing millet or sudan grass. The treatments consisted of: pearl millet (Pennisetum americanum (L.) Leeke) or sudan grass (Sorghum bicolor cv. Sudanense). Both treatments were submitted to continuous grazing of cull cows over 63 experimental days subdivided into three periods. Using 20 Charolais x Nellore cull cows, at the average age of 8 years and average weight of 445 kg. The animals were divided into 10 paddocks, five paddocks used for each treatment comprising two cows. The behavioral assessments were carried out for 24 hours straight. The experimental design was completely randomized with two treatments and three periods. The grazing time of cows showed interaction (P = 0.0035) between treatment and period, and the shortest time for the activity in the first period on pearl millet (504 minutes) compared to the second period of that same treatment (587 minutes) and the third period on sudan grass pastures (535 minutes). The times of rumination and idling were similar between treatments; however, the idling time decreased and rumination increased with time periods. The forage species did not affect the variables related to the strategies of displacement and feeding. With the advancement of cycle pastures the number of steps per minute, stations per minute and per day decreased while the bite rate and the number of bites per day increased. The behavioral parameters of cull cows grazing sudan grass or millet are similar; however, the advancement of the vegetative cycle of these species provides changes in the behavioral pattern of the animals.KEYWORDS: bit rate; displacement strategies; grasses; grazing time; Pennisetum; Sorghum.

The effect of preceding crop on wheat grain zinc concentration and its relationship to total amino acids and dissolved organic carbon in rhizosphere soil solution

The role of cropping systems practices in agronomic biofortification programs with the aim of increasing micronutrient density in food plants has to be clarified. In these field experiments, the effect of four preceding crops, i.e., sunflower (Heliantus annus L. cv. Allstar), Sudan grass (Sorghum bicolor L. cv. Speed Feed), clover (Trifolium pratense L.), and safflower (Carthamus tinctorius L. cv. Koseh-e-Isfahan), on the total amino acids (AA) and dissolved organic carbon (DOC) concentration in rhizosphere soil solution and grain Zn content of successive wheat (Triticum aestivum cvs. Back Cross and Kavir) was investigated during 2009–2010 and 2010–2011 growing seasons. A fallow treatment was also considered as the control. In both growing seasons, preceding crops increased the concentrations of AA and DOC in the soil solution in comparison with the fallow control treatment; although the magnitude of this increase varied upon the preceding crop type and wheat cultivar. In general, clover and sunflower had greater effect on increasing soil solution DOC probably due to higher decomposability of their litter residues in soil. Preceding crops increased the total AA concentration, on average, by 45.9 % for the first year and 10.8 % for the second year. The preceding sorghum and clover had the highest and lowest influence on the concentration of AA in wheat rhizosphere soil solution, respectively. The preceding crops increased grain wheat Zn concentration and content over the fallow control treatment, although this effect was dependent on the crop type. For “Back Cross”, a positive and significant correlation was found between grain Zn concentration and soil solution DOC concentration (r = 0.60, P < 0.05) and particularly AA (r = 0.76, P < 0.001), while no such correlation was found for “Kavir”. At the second growing season, the concentration of AA in the rhizosphere of Back Cross was greater than that of Kavir, probably due to higher release of these compounds from the roots. According to the results, the preceding crop significantly affect grain Zn density of the successive wheat, that is, at least in part, by releasing soluble organic ligands into soil solution.

Fusarium oxysporum f.sp. cepae dynamics: in-plant multiplication and crop sequence simulations

To reduce Fusarium Basal Rot caused by Fusarium oxysporum f.sp. cepae (Foc) through crop rotation, plant species should be selected based on Foc multiplication in their roots. Foc multiplication rates in 13 plant species were tested in a greenhouse. All plant species enabled Foc multiplication. The lowest Foc levels (cfu g−1 dry root) were found for wheat, sunflower, cowpea and millet, the highest for black bean. The highest Foc levels per plant were calculated for sudan grass. These data were used to calibrate the model Pf = Pi/(α + βPi) relating final (Pf) and initial (Pi) Foc levels in the soil. The rate of population increase at low Pi (1/α) was highest for onion and black oat and smallest for sunflower. The pathogen carrying capacity (1/β) was highest for black oat and black bean, and lowest for wheat, cowpea and foxtail millet. Foc soil population dynamics was simulated for crop sequences by concatenating Pi-Pf values, considering instantaneous or gradual pathogen release after harvest. Different soil Foc populations were attained after reaching steady states. Foc populations in the sequence onion –foxtail millet - wheat – cowpea were 67 % lower than in the sequence onion – sudan grass - black oat - black beans. In this work, by combining detailed greenhouse experiments with modelling, we were able to screen crops for their ability to increase Foc population and to explore potential crop sequences that may limit pathogen build-up.

Seasonal dynamics of CO2 balance and water consumption of C3 and C4-type cover crops compared to bare soil in a suitability study for their use in vineyards in Germany and Argentina

Cover crops are used in vineyards to maintain soil structure, minimise soil erosion and optimise vineyard mechanisation, yet few data are available on water consumption and carbon dioxide assimilation (CO2). Whereas cover crop use is common in the grape growing regions of Germany it is uncommon in Argentina. To obtain some information on the suitability of a selected number of species in terms of carbon gain and water expenditure under the climatic conditions of Germany and Argentina, we first quantified evapotranspiration (EvT), CO2 assimilation and water use efficiency of Trifolium repens L. (white clover) (TR), Festuca arundinacea Schreb (tall fescue) (FE), Sorghum sudanense (Piper) Stapf (Sudan grass) (SO), and Digitaria californica (Benth) Henr. (Arizona cotton top) (DI) in a field trial in Geisenheim, Germany. We then compared the performance of TR, FE and DI together with Sorghum halepense L. (Johnson grass) (SH) in a pot experiment under the warmer climatic conditions of Mendoza, Argentina, where water supply could be controlled. In all cases bare soil served as a reference for soil water loss. Gas-exchange of plants and soil were measured with customised open system canopy chambers and an infrared gas analyser and water dynamics in the soil with soil moisture probes (field) or gravimetrically (pots). SO and TR were the two species that reached the highest degree of soil coverage in Germany and substantially reduced soil moisture in the first 0.40m of depth. TR showed high EvT and CO2 assimilation rates in both climates when water supply was sufficient and maintained relative high rates when water status was reduced under cool conditions in Germany, yet performed poorly when high temperatures occurred concomitant to low water supply in Argentina. DI, being a C4 species from arid regions, had difficulties to get established in the cool conditions of Germany and there was no clear tendency for more efficient water use than the other cover crops. However under the warm condition of Argentina, especially when water supply was reduced, DI displayed higher WUE which was entirely related to the maintenance of higher assimilation rates at substantially reduced EvT. FE being common in German vineyards had low assimilation rates combined with high evapotranspiration rates under Argentinian conditions and was very sensitive to water deficit in combination with high temperature.

Potential application of anaerobic digestion to tobacco plant

In this work, the energetic feasibility of using tobacco (not tobacco waste materials) as a raw material in the process of anaerobic digestion has been studied in terms of methane production, in order to demonstrate the potentiality of tobacco plant to be used as an energy crop.Long-term experiments have been performed at the laboratory scale with and without a regulation of the substrate pH and within the mesophilic range (38°C). Methane production and the parameters that control the anaerobic digestion process have been monitored periodically. The highest methane production, 53.84Nm3 methane/tonne of fresh tobacco, and a chemical oxygen demand reduction of 53.26% were achieved when the substrate with 15% tobacco (m/m) was treated with a hydraulic retention time of 16days.In addition, biomethanisation of this substrate can recover 57% of the water contained in the mixture, which can be used for irrigation of the tobacco crop.It should be noted that pH regulation is essential to ensure the stability of the biological process, since all the experiments was carried out with the natural pH showed signs of inhibition.These outputs of methane are on the same order as those obtained from other substrates, such as Sudan grass, fodder beet, and millet and place an industrial plant for tobacco biomethanation at the edge of economic profitability.

EFFECT OF THE SOWING TIME ON SOME BIO–PRODUCTIVE PARAMETERS OF ANNUAL SUMMER FORAGE MIXTURE

During the 2010–2012 periods in the Research Institute of Mountain Stockbreeding and Agriculture (RIMSA) in Troyan the effect of sowing time on some bio–productive parameters of the forage from annual summer mixture was performed. It was established that the most optimal time for sowing of annual summer mixture from sorghum–Sudan grass hybrid and horse bean grown under the foothill conditions of Central Balkan Mountains (Troyan region) is period from 1 to 10 of July. The received forage amounted to 2.20 t. ha green mass and 0.50 t. ha dry matter, which exceeded the later sowing periods from 7.55% (from 11 to 20 July) to 61.93% (from 1 to 10 August) and from 16.28 to 65.98%. There was a least weed infestation of mixture at last sowing period (from 1 to 10 August) and reached 3.03–3.85%.

Impact of co-digestion on existing salt and nutrient mass balances for a full-scale dairy energy project

Anaerobic digestion of manure and other agricultural waste streams with subsequent energy production can result in more sustainable dairy operations; however, importation of digester feedstocks onto dairy farms alters previously established carbon, nutrient, and salinity mass balances. Salt and nutrient mass balance must be maintained to avoid groundwater contamination and salination. To better understand salt and nutrient contributions of imported methane-producing substrates, a mass balance for a full-scale dairy biomass energy project was developed for solids, carbon, nitrogen, sulfur, phosphorus, chloride, and potassium. Digester feedstocks, consisting of thickened manure flush-water slurry, screened manure solids, sudan grass silage, and feed-waste, were tracked separately in the mass balance. The error in mass balance closure for most elements was less than 5%. Manure contributed 69.2% of influent dry matter while contributing 77.7% of nitrogen, 90.9% of sulfur, and 73.4% of phosphorus. Sudan grass silage contributed high quantities of chloride and potassium, 33.3% and 43.4%, respectively, relative to the dry matter contribution of 22.3%. Five potential off-site co-digestates (egg waste, grape pomace, milk waste, pasta waste, whey wastewater) were evaluated for anaerobic digestion based on salt and nutrient content in addition to bio-methane potential. Egg waste and wine grape pomace appeared the most promising co-digestates due to their high methane potentials relative to bulk volume. Increasing power production from the current rate of 369 kW to the design value of 710 kW would require co-digestion with either 26800 L d−1 egg waste or 60900 kg d−1 grape pomace. However, importation of egg waste would more than double nitrogen loading, resulting in an increase of 172% above the baseline while co-digestion with grape pomace would increase potassium by 279%. Careful selection of imported co-digestates and management of digester effluent is required to manage salt and nutrient mass loadings and reduce groundwater impacts.

Survival of Hessian Fly (Diptera: Cecidomyiidae) Puparia Exposed to Simulated Hay Harvest Conditions, Location and Windrow Drying in Washington and California

Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae) puparia are of regulatory concern in exported hay, and drying after harvest was evaluated as a cultural control technique for bales shipped from the western states. In total 16,836; 31,122; and 48,051 puparia were tested under drying conditions in environmental chambers, open air on location, and hay windrows, respectively. Regression lines for percentage of total adults emerging from puparia exposed to simulated drying conditions for 1-7 d in environmental chambers was significant for 1 September, Kittitas Valley, WA; 3 June, East Columbia Basin, WA; 15 May and 15 July, San Joaquin Valley, CA; and 15 May, 20 July, and 15 September, Imperial Valley, CA. In open air drying on location for 1-7 d, total percentage of puparia surviving to adults for all exposure days was 0.4% for 18 June, Kittitas Valley; 1.2% for 15 May, San Joaquin Valley; and 0% for 16 July, Imperial Valley; and significantly different between controls and exposure durations. In hay windrow drying for 1-6 d, total percentage of puparia surviving to adults for all exposure days was 5.4% on 28 June and 24.2% on 7 September in timothy, Phleum pretense, in the Kittitas Valley; 3.8% on 28 June in timothy in the East Columbia Basin; 2.2% on 20 July in alfalfa, Medicago sativa, in the San Joaquin Valley; and 6.3% on 21 July in Sudan grass, Sorghum bicolor sudanensis, in the Imperial Valley. The number of puparia surviving to adults in open air drying and in windrows was significantly different between controls and exposure durations for all test dates and locations. Puparial survival in field tests was related to mild temperatures and high humidities. Hay drying with subsequent field baling, storage, and export bale compression is discussed in relation to a systems approach for quarantine control of Hessian fly in exported hay.

The manipulation mechanism of “push–pull” habitat management strategy and advances in its application

The “push–pull” habitat management strategy, as a new powerful and effective tool in integrated pest management (IPM), uses a combination of behavior-modifying stimuli to manipulate the distribution and abundance of pests and/or their natural enemies for pest control. In the “push–pull” strategy, pests are repelled or deterred away from the protected resource (push) by stimuli that disturb the host location and modulate the host become unattractive or unsuitable for the feeding and oviposition of pests. By using highly attractive stimuli, the target pests are simultaneously attracted (pull) to the specific source in which they are subsequently concentrated, facilitating their elimination and leaving the protected resource. Since stimuli usually are nontoxic, either “push” or “pull” components, the strategy is usually companied by population-reduced methods, such as using insecticides, exploiting nature enemies, and placing traps. Among them, methods of biological control are the most preferred. The “push–pull” strategies maximize efficacy of behavior-modifying stimuli through the additive and synergistic effects of integrating the use of methods for population reduction. In this review, the principles of the “push–pull” strategy were firstly described, then the potential behavior-modifying stimuli for “push” and “pull” components were introduced. The stimuli for use in “push–pull” strategies primarily include visual cues and chemical cues (synthetic or plant- or insect-derived semiochemicals). Visual stimuli, repellent and trap plants, host and non-host volatiles, insect pheromones, and antifeedants and oviposition deterrents are usually applied as the potential stimuli in the “push–pull” strategy for pest control. The stimuli are grouped as long-range stimuli and short-range stimuli. In addition, we also summarize models of “push–pull” habitat management strategy, such as agriculture, horticulture and forestry, of pest control and some successful case studies in applying of “push–pull” strategy and its potential ecological benefits. The “push–pull” technology (PPT), so far the most effective “push–pull” strategy in practice by farmers, developed for management of both stemborers and Striga hermonthica in maize-based farming system in eastern Africa were reviewed. The PPT uses an intercrop of repellent plants and border crops of attractive trap plants. Stemborer moths are effectively repelled away from the maize crop (push) by Desmodium and molasses grass, and are subsequently attracted (or trapped) to (pull) by the Napier grass and Sudan grass which emit the green leaf volatiles (GLVs) showing attractant properties. Finally, the problems in current research and future perspectives of the “push–pull” habitat management strategy are discussed in the present paper.

Susceptibilidade de espécies de plantas com potencial de fitorremediação do herbicida sulfentrazone

Dentre as novas tecnologias, a fitorremediação é opção para a descontaminação de áreas que receberam intensas aplicações de herbicidas. Este trabalho foi desenvolvido com o objetivo de selecionar espécies com potencial para a fitorremediação de solos contaminados com o herbicida sulfentrazone. As espécies testadas foram: Calopogonium mucunoides, híbrido de sorgo (Sorghum bicolor x Sorghum sudanense), Crotalaria breviflora, Crotalaria juncea, Canavalia ensiformis, Dolichos lablab, Stizolobium deeringianum e Stizolobium aterrimum, cultivadas em cinco doses do sulfentrazone (0, 200, 400, 800 e 1.600 g ha-1). O experimento foi instalado em casa de vegetação, utilizando-se vasos com capacidade para 6 L, preenchidos com amostras de solo coletadas na profundidade de 0-20 cm. Foram avaliadas a fitotoxicidade do herbicida, a altura de plantas e a massa de matéria seca da parte aérea e de raízes. As espécies que manifestaram os menores sintomas de fitotoxicidade e os maiores índices de altura e matéria fresca e seca foram C. juncea, C. ensiformis e D. lablab, sendo selecionadas como tolerantes ao herbicida sulfentrazone e com potencial para fitorremediação.

Effects of inoculation with stress-adapted arbuscular mycorrhizal fungus Glomus deserticola on growth of Solanum melogena L. and Sorghum sudanese Staph. seedlings under salinity and heavy metal stress conditions

The beneficial effects of a Glomus deserticola strain isolated from the rhizosphere of grasses (belonging to Poaceae family) growing along the industrial waste from a distillery were investigated under stress conditions. The study was conducted to assess the efficacy of the arbuscular mycorrhizal (AM) fungal ecotype in salinity and heavy metal (HM) tolerance of eggplant (Solanum melongena L.) in soils amended with various stress levels of NaCl, zinc and cadmium. Mycorrhizal (M) seedlings produced a significantly (p < 0.05) greater growth response and were more tolerant to salt and HM stresses than nonmycorrhizal (NM) seedlings in all treatments. The HM contents in the plant tissues were significantly higher in M than NM eggplants. Furthermore, when the efficacy was compared with other AM isolates in HM-polluted soils with Sudan grass (Sorghum sudanese Staph.) as a test plant, the AM ecotype responded best to these soils, as evident from the significantly greater growth response and its aggressiveness in colonizing roots in all soil types tested. These results suggest that this G. deserticola ecotype can be used as an effective tool to alleviate the adverse effects of excessive salinity and HM toxicity on plant growth. Finally, the isolate may have potential in the bioremediation of polluted soils.

Grain yield production of Sudan grass (Sorghum sudanense (Piper) Stapf) as influenced by cutting numbers, potassium rates, and intrarow spacing in a semiarid environment

The seed scarcity of Sudan grass plagues the pasture industry in the livestock sector, especially in arid and semiarid regions. The current study was initiated to tackle this challenge. The study evaluates the response of the grain yield and yield components of Sudan grass to cutting numbers, potassium rates, and intrarow spacing over 2 years. A field experiment was conducted using a randomized complete block split-split design with 2 cutting numbers (no cutting and cut 1 time), 2 potassium rates (60 and 120 kg K_2O ha^{-1}), and 3 intrarow spacings (15, 20, and 25 cm between hills) as the main plot, split plot, and split-split plot, respectively. The results showed that the zero-cut treatment produced, as averaged over the 2 seasons, 52.3% and 74.5% higher grain yield and hay yield per hectare than the one-cut treatment, respectively. However, the latter treatment had harvest index and sum of hay and green forage yield values that were 17.0% and 19.9% higher than those of the zero-cut treatment, respectively. The application of potassium at a rate of 120 kg ha^{-1} resulted in the maximum grain yield and yield components as compared to the lower potassium rate (60 kg ha^{-1}), with the exception of 1000-grain weight, hay yield, and sum of hay and green forage yield, which were not significantly different from each other. Averaged over 2 seasons, as the intrarow spacing between hills was increased from 15 cm to 20 and 25 cm, grain weight per panicle decreased by 11.3% and 25.7%, grain yield per hectare decreased by 6.6% and 15.7%, and harvest index decreased by 12.0% and 23.5%, respectively. The interaction among 3 factors had a significant effect on yield and yield components; the highest values for grain and hay yields per hectare were obtained by growing Sudan grass at 15 or 20 cm intrarow spacing under the zero-cut treatment with the application of potassium at rate of 120 kg ha^{-1}. At 15 or 20 cm intrarow spacing, the values for grain yield per hectare under the one-cut treatment and high potassium rate were occasionally comparable to those for the zero-cut treatment and low potassium rate. Finally, when seed production is desired, Sudan grass should not be cut. If growers are interested in producing green forage and grain simultaneously, Sudan grass can be cut 1 time; however, it should be grown at 15 cm intrarow spacing with application of potassium at a rate of 120 kg ha^{-1}.

Transforming Saltbush: Science, Mobility, and Metaphor in the Remaking of Intercolonial Worlds

The movement of exotic biota into native ecosystems are central to debates about the acclimatisation of plants in the settler colonies of the nineteenth century. For example, plants like lucerne from Europe and sudan grass from South Africa were transferred to Australia to support pastoral economies. The saltbush Atriplex spp. is an anomaly-it too, eventually, became the subject of acclimatisation within its native Australia because it was also deemed useful to the pastoralists of arid and semi-arid New South Wales. When settlers first came to this part of Australia, however, initial perceptions were that the plants were useless. We trace this transformation from the desert 'desperation' plant during early settlement to the 'precious' conservation species, from the 1880s, when there were changes in both management strategies and cultural responses to saltbush in Australia. This reconsideration can be seen in scientific assessments and experiments, in the way that it was commoditised by seeds and nursery traders, and in its use as a metaphor in bush poetry to connote a gendered nationalist figure in Saltbush Bill. We argue that while initial settlers were often so optimistic about European management techniques, they had nothing but contempt for indigenous plants. The later impulses to the conservation of natives arose from experiences of bitter failure and despair over attempts to impose European methods, which in turn forced this re-evaluation of Australian species.

Efficiency of single-species and two-component mixtures of legume and cereal crops for fodder in the south Urals steppe zone

The main characteristics of high productivity agrophytocenoses of single-species and mixed crops of Sudan grass, oat, millet, vetch, and annual sweet clover are examined. The ability of annual sweet clover in a single-species crop and its mixture with Sudan grass to produce up to 14.8 t/ha green mass and 4.5 t/ha dry matter in two cuts with a yield of 3700/ha feed units, 70.0 GJ/ha gross energy, and 37.7 GJ/ha metabolizable energy is established.

Herbage production from five grazable forages

Maintaining an adequate feed supply throughout the year is an important consideration in dairy systems. Systems based on perennial ryegrass pastures are often limited by poor growth and feed quality when soil moisture is low and temperatures are high. Alternative forage species better adapted to these conditions may provide options for maintaining feed supply. Annual and seasonal dry matter (DM) production, and nutritive value of five grazable forages with and without irrigation were compared under cutting in the Waikato over two successive years. Perennial ryegrass produced the greatest annual DM yield in both years under both irrigation regimes, largely through superior cool season production and mild temperatures with above average rainfall during the experiment. Plantain tended to provide more DM than perennial ryegrass under irrigation in summer and autumn, a time when additional DM is important for maintaining milk production. With the exception of sudan grass, nutritive value of all forages exceeded values expected to limit milk production. Keywords: dry matter yield, nutritive value, chicory, plantain, perennial ryegrass, sudan grass, sulla

Morphological characteristics of the interspecies hybrid between Sorghum and Sudan grass under intensive nitrogen nutrition

The object of this study was a two-year trial (2009 and 2010) regarding variability of morphological characteristics of species belonging to Sorghum genus, more specifically interspecies hybrid between sorghum and Sudan grass Siloking as affected by different applications of nitrogen. The following morphological characteristics were analysed: plant height, number of leaves, leaf ratio, stem ratio, and number of shoots. Samples were taken from the first cut when the effect of the applied nitrogen doses was the strongest. The results showed that increasing nitrogen quantities significantly affected the tested morphological characteristics, especially the intensity of tillering (increased number of secondary stems), number of the formed leaves, and ratio of leaf weight in the total above-ground biomass. The effect of applied nitrogen depended on the weather conditions, i.e. distribution of precipitation, so that plants reached maximum height when 105 kg N ha-1 was applied in the dry year and 180 kg N ha-1 in the wet year.

Inducing variability in multi-cut forage sorghum through mutagenesis

Improvement in multi-cut forage sorghum varieties that can perform better than SSG 59-3, a sweet Sudan grass released in 1974, has been a challenge. Efforts were made to create variability in SSG 59-3 through mutagenesis using both physical and chemical mutagens. Fifteen such mutants were evaluated for 2 years in different locations in India. Considerable variability was observed for important fodder yield and quality traits. SSG 237 flowered 10 d early than SSG 59-3. SSG 231, SSG 260, SSG 232 and SSG 237 had high protein percentage andin vitrodry matter digestibility (IVDMD) values compared with SSG 59-3. Hydrocyanic acid (HCN), a major anti-nutritional factor, was low in six mutants, the lowest being in SSG 226. This variability can be used in different breeding programmes aimed at improving multi-cut forage sorghum varieties. The lines with improved fodder quality (low HCN, high protein and IVDMD) can be used in the breeding programme for the improvement in multi-cut forage sorghum varieties.

Growth and Cu and Zn uptake of two forage grasses affected by application of vermicompost spiked with different metal contents

To identify environmental risks of vermicompost-borne pollutants after consecutive application for different times, pot experiments were conducted to evaluate the effects of application of polluted vermicompost produced by Eisenia fetida on growth and Cu and Zn uptake of Mexico corn (Euchlaena mexicana) and Sudan grass (Sorghum hybrid Sudangrass) as well as soil characteristics. The results showed that application of vermicompost significantly increased shoot biomass of the two forage grasses, but decreased Mexico corn root biomass. Tissue Cu and Zn contents and soil bio-available fractions of Cu and Zn were significantly increased as the increase of application times, while soil pH and water soluble organic carbon (DOC) decreased. A significantly positive correlation was obtained between soil exchangeable and reducible fractions of Cu and Zn and forage grass tissue metal contents, whereas DOC performed a significantly negative correlation. So, application of polluted vermicompost could contribute to accumulate of soil Cu and Zn exchangeable and reducible fractions, and pose a potential threat to increase tissue Cu and Zn contents of the cultured plants. Key words: Vermicompost, Cu and Zn, tissue uptake, biomass, fractionations.