Ethanol production from supercritical-fluid-extrusion cooked sorghum

Sorghum (Sorghum bicolor (L.) Moench) is a starch-rich grain similar to maize (Zea mays L.), but sorghum has been underutilized for biobased products and bioenergy. This study was designed to investigate the effects of supercritical-fluid-extrusion (SCFX) of sorghum on ethanol production. Morphology, chemical composition, and thermal properties of extruded sorghum were characterized. Analysis of extruded sorghum showed increased measurable starch content, free sugar content, and high levels of gelatinized starch. SCFX cooked and non-extruded sorghum were further liquefied, saccharified, and fermented to ethanol by using Saccharomyces cervisiae. The ethanol yield increased as sorghum concentration increased from 20 to 40% for both extruded and non-extruded sorghum. Ethanol yields from SCFX cooked sorghum were significantly greater than that from non-extruded sorghum (>5%).     

Alternate crop and weed host plant oviposition preferences by the Mexican rice borer (Lepidoptera: Crambidae)

The Mexican rice borer, Eoreuma loftini (Dyar), is the key pest of sugarcane, Saccharum hybrids, in south Texas, having largely displaced the sugarcane borer, Diatraea saccharalis (F.), and it is moving into rice- and sugarcane-growing areas of east Texas and Louisiana. While a number of alternative weed and crop hosts have been reported, the extent to which they might support Mexican rice borer populations is unknown. This study involved choice assays that compared oviposition preference for and larval infestations of five mature graminaceous weed species. Levels of infestation between sugarcane and corn, Zea mays L., crop hosts and between corn and sorghum, Sorghum bicolor (L.) Moench, were also assessed. We determined that the average number of larval entry holes in sudangrass stems was ≥2.5-fold more than for any of the other four weed host plants, that corn had ≥5.9-fold more larval entry holes than sorghum and ≥8.2-fold more than sugarcane. Greater oviposition and infestation of one non-crop host over another was not related to numbers of stems per plant, but was associated with the greater stem diameter and abundance of dry leaf tissue found in Sudangrass, Sorghum bicolor (L.) Moench ssp. drummondi (Nees ex Steud.) de Wet & Harlan, johnsongrass, S. halepense (L.) and barnyardgrass, Echinochloa crus-galli (L.) P. Beauv.; relative to the other weed species in this study. In terms of the crop plants, stalk diameter and quantity of dry leaf tissue were not associated with numbers of eggs or larval entry holes in the choice assays between corn and sorghum, and between sugarcane and corn. While corn has been known as a host of the Mexican rice borer for at least 84 yr, its role in area-wide population dynamics and control efforts has likely been greatly underestimated.     

Elevated atmospheric CO2 effects on N fertilization in grain sorghum and soybean

Increasing atmospheric CO₂ concentration has led to concerns about global changes to the environment. One area of global change that has not been fully addressed is the effect of elevated atmospheric CO₂ on agriculture production inputs. Elevated CO₂ concentration alterations of plant growth and C:N ratios may modify C and N cycling in soil and N fertility. This study was conducted to examine the effects of legume, soybean (Glycine max (L.) Merr.), and non-legume, grain sorghum (Sorghum bicolor (L.) Moench.) carbon dioxide-enriched agro-ecosystems on N soil fertility in a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults). The study was a split-plot design replicated three times with crop species (soybean and grain sorghum) as the main plots and CO₂ concentration (ambient and twice ambient) as subplots using open top field chambers. Fertilizer application was made with ${}^{15}\text{N}$-depleted NH₄NO₃ to act as a fertilizer tracer. Elevated CO₂ increased total biomass production in all 3 years of both grain sorghum (average 30%) and soybean (average 40%). With soybean, while no impact on the plant C:N ratio was observed, the total N content was greatly increased (average 29%) due to increased atmospheric N₂ fixation with elevated CO₂ concentration. With grain sorghum, the total N uptake was not affected, but the C:N ratio was markedly increased (average 31%) by elevated CO₂. No impact of elevated CO₂ level was observed for fertilizer N in grain sorghum. The results from this study indicated that while elevated CO₂ may enhance crop production and change N status in plant tissue, changes to soil N fertilizer application practices may not be needed.     

Efficacy of postemergence herbicides tankmixes in aryloxyphenoxypropionate-resistant grain sorghum

The development of aryloxyphenoxypropionate (APP)-resistant grain sorghum could provide additional opportunities for postemergence herbicide grass control in grain sorghum. Field experiments were conducted in Texas (Bushland, and Yoakum), Kansas (Dodge City, Garden City, Hays, Manhattan, Colby, Ottawa, and Tribune), and South Dakota (Highmore) to evaluate the efficacy of quizalofop tank mixes in APP-resistant grain sorghum. Quizalofop was applied alone or in combination with dicamba, 2,4-D, prosulfuron, 2,4-D + metsulfuron methyl, or halosulfuron methyl + dicamba. Herbicides were applied when sorghum was 12–50 cm in height. Overall weed control was greater when quizalofop was applied with other herbicides than when applied alone. At 2 and 4 weeks after treatment (WAT), large crabgrass [Digitaria sanguinalis (L.) Scop.], giant foxtail (Setaria faberi Herrm.), and green foxtail [Setaria viridis (L.) Beauv.] control were greater than 90% when quizalofop was applied alone or in combination with dicamba, halosulfuron methyl + dicamba, or prosulfuron. Palmer amaranth (Amaranthus palmeri S. Wats.), puncturevine (Tribulus terrestris L.), and tumble pigweed (Amaranthus albus L.) control were greater than 90% in all treatments except when quizalofop was applied alone. Herbicide treatments, except those that included 2,4-D, caused slight to no sorghum injury. Grain sorghum yield was greater for all herbicide treatments compared to the weedy check. This research showed that application of quizalofop in combination with broadleaf weed herbicides provided excellent weed control in sorghum.     

Response of pearl millet to grain sorghum environments

Increasing awareness of drought tolerance in pearl millet [Pennisetum americanum (L.) Leeke.] has stimulated research into pearl millet as a potential U.S. crop. Objectives of this study were to compare yield and yield components of pearl millet and grain sorghum [Sorghum bicolor (L.) Moench] and evaluate pearl millet response to a range of grain sorghum environments.Yield and yield component comparisons were made using 24 millet hybrids and six grain sorghum hybrids at seven Kansas locations, from 1980 to 1982. To compare pearl millet production in grain sorghum environments, millet hybrid mean yields were regressed on sorghum location means. A desirable millet hybrid would have a high yield and a regression coefficient not significantly different from 1.0.Average grain sorghum yields were greater than millet yields in all three years. Millet hybrid yields ranged from 350 to 5400 kg ha⁻¹. Over all locations and years, millet yield averaged 63% of sorghum yield.In unfavorable environments, pearl millet yield and response to changing environments were not significantly different from those of grain sorghum. As environmental conditions improved, sorghum significantly yielded more than millet. Lower millet yields could be attributed to significantly smaller seed size and head sterility. The small seed also reduced plant establishment; however millet's tillering ability compensated for reduced population.     

Impact of managing cover crop residues on the floristic composition and species diversity of the weed community of pepper crop (Capsicum annuum L.)

The decline of farmland biodiversity is mainly attributed to the intensive use of chemical inputs in agriculture. Cover crop residues may contribute to improve weed management while maintaining a high level of weed diversity. A 2-year field experiment was carried out in central Italy to study the effect of cover crop species and their residue management on weed community composition and weed species diversity in a winter cover crop – pepper sequence. Hairy vetch (Vicia villosa Roth.), oat (Avena sativa L.) and canola (Brassica napus L.) were sown in September 2009 and 2010 and grew undisturbed during the winter season until spring when they were suppressed one week before pepper transplanting. Cover crop residues were: (i) green manured at 30 cm depth (conventional tillage, CT), (ii) green manured at 10 cm depth (minimum tillage, MT), and (iii) left on the soil surface as mulch strips covering 50% of the ground area in no-tilled soil (NT). A winter weedy fallow and a bare soil without cover crop in NT, MT and CT were also included as controls. Weed plant density data in pepper were used for calculating weed species richness. Compared to weedy fallow, oat, hairy vetch and canola consistently reduced the weed density and weed aboveground biomass by the time of their suppression (on average 3.6, 21.5, and 41.3 plants m⁻² and 11.0, 49.2, and 161.8 g m⁻² of DM, respectively). In pepper, oat residues generally determined a higher reduction of weed density and species richness compared to hairy vetch and canola regardless the residue management treatments. Converting cover crop aboveground biomass into mulch strips greatly reduced weed species density but did not always imply a reduction of weed species diversity in pepper compared to MT and CT. The weed species richness was reduced inside the mulch strips, while a richer and more diverse weed community was found outside the mulch strips in NT. Weed community in pepper was mainly composed of annual dicot weeds such as Amaranthus retroflexus, Chenopodium album, Solanum nigrum, Polygonum aviculare which were mostly associated with MT and CT tillage systems, while in NT an increase of perennial species such as Rumex crispus was observed. These results suggest that it is possible to manage cover crop residues in NT in order to obtain a lower weed density and consequently a higher yield in pepper compared to MT and CT while maintaining a high level of weed diversity.     

Impact of nitrogen fertilization on Mexican rice borer (Lepidoptera: Crambidae) injury and yield in bioenergy sorghum

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is a serious pest of sugarcane (Saccharum spp.), sorghum (Sorghum bicolor (L.) Moench), corn (Zea mays L.), rice (Oryza sativa L.), and related graminaceous bioenergy crops. A two-year field study was conducted in Jefferson County, TX to examine the impact of nitrogen (N) fertilization on E. loftini infestations and subsequent yields in cultivars of high-biomass and sweet sorghum. In 2013, percentage of bored internodes and number of adult emergence holes per stalk increased with higher N rates; however, only the percentage of bored internodes was impacted by N in 2014. Yields from both years indicated that N rate was positively associated with increases in stalk weight and ethanol productivity, but not sucrose concentration. Because higher N rates were associated with increased yields despite having greater levels of E. loftini injury, our data suggest that increases in yield from additional N outweigh decreases from additional E. loftini injury. Fertilization rates maintained between the recommended 45 and 90 kg N/ha minimize risks of negative area-wide impacts from increased production of E. loftini adults, while still allowing for optimum yields.     

Analysis of seed yield components in four Mediterranean annual clovers

Annual leguminous forage crops are well adapted to hay production under the climatic conditions of Mediterranean environments, but their seed yield is often reduced by high temperatures and water stress that occur during the reproductive period. Field experiments using four forage legumes, berseem (Trifolium alexandrinum L.), crimson clover (Trifolium incarnatum L.), Persian clover (Trifolium resupinatum L.) and squarrosum clover (Trifolium squarrosum L.) were conducted in Foggia (southern Italy) during 1993 and 1994 under irrigated and non-irrigated conditions, with the aim to evaluate: (i) the effects of water deficit on traits which influence seed yield and (ii) the associations among seed yield components by means of path-coefficient analysis. Seed yield varied among species: Persian and berseem clovers showed the highest and lowest values (74.0 and 27.0 g m⁻², respectively). Drought stress, in all species, negatively influenced the dry matter proportion partitioned to reproductive growth and strongly reduced seed yield (about 50% on average) and seed yield components in all species. Negative associations between the principal yield components were found in all species except berseem, suggesting the existence of compensatory relationships. Path-coefficient analysis revealed that for crimson and Persian clovers, the early flowering species, a seed yield increase cannot be achieved without a suitable tiller density. For squarrosum clover, the head fertility was the most important component in determining seed yield; whereas for berseem, seeds per head, heads per tiller and seed weight, all had positive direct effects on seed yield. As the yield components that most affected seed yield were species-specific, general conclusions cannot be drawn. Among the species examined, berseem and squarrosum clover, characterized by a longer vegetative cycle, were more damaged by water stress when it occurred during seed formation and filling.     

Dual and Triple Intercropping: Potential Benefits for Annual Green Manure Production

Abstract

Greater species diversity in natural ecosystems increases plant biomass production and stability. Intercropping is an agricultural practice that aims to accrue the benefits of species diversity by growing two or more species simultaneously in the same space. Functional group diversity is considered important for enhancing the beneficial effects of species diversity, but most previous intercropping studies used combinations of only two functional groups. Thus, we used three green manure species from different functional groups: sorghum (Sorghum bicolor (L.) Moench.), a C4 grass; crotalaria (Crotalaria juncea L.), a legume; and sunflower (Helianthus annuus L.), a forb. We examined the effects of intercropping on biomass, nutrient uptake, and their stability using a proportional replacement series in a field experiment for three years with four trials. The aboveground biomass was higher with dual and triple-component intercrops compared with sole crops; however, there were no superior effects of triple-component intercropping over dual-component intercropping. There were also no clear advantages of intercropping in terms of the nutrient uptake amount and stability.     

Relations between summer crops and ground cover legumes in a subtropical environment 2. Effects of sorghum and sunflower on the growth of Vigna trilobata and Medicago scutellata

Vigna trilobata (L.) Verdc. is a low growing legume with potential as a ground cover for controlling soil erosion in cropping lands of the subhumid/semi-arid subtropics of northern Australia. When it was grown beneath sorghum (Sorghum bicolor (L.) Moench) and sunflower (Helianthus annuus L.) crops under well-watered conditions on a vertisol in southern Queensland it decreased their yields by about 20% in the first season. This paper reports the effects of competition from crops sown at a normal dryland density or at half the normal density on its growth.V. trilobata sown in pure stand in October produced 531 g m⁻² of above-ground dry matter, and sown in January produced 323 g m⁻², by the time the grain crops sown at the same time were mature. Yields under mature sorghum sown at the normal density (10 plants m⁻²) in October and January were 38% and 35% respectively of those from pure stands of ground cover sown at the same time. Under sunflower at the normal density (5 plants m⁻²), corresponding values were 42% and 22%. The decrease in dry matter yield attributable to competition for water, nutrients and/or radiation from the main crops was proportional to the decrease in intercepted radiation.V. trilobata responded to shade in several ways, but a substantial increase in specific leaf area, together with some additional partitioning of dry matter to leaf, was sufficient to ensure that its leaf area index under crops was similar to that in pure stands.Seed yields of 116 and 84 g m⁻² were obtained from pure stands of V. trilobata sown in October and January respectively. However, seed yields under crops sown at the normal density were only 4–18% of those measured in pure stands. Seed size was not affected by treatment.We conclude that, under well-watered conditions in southern Queensland, V. trilobata grown as a ground cover under crops of sorghum and sunflower should be able to produce sufficient biomass to decrease soil erosion, and also produce sufficient seed for regeneration in successive seasons. Its growth and suitability are also briefly compared with those of an alternative ground cover legume, Medicago scutellata (L.) Mill. (snail medic).     

Biomass sorghum production and components under different irrigation/tillage systems for the southeastern U.S.

Renewable energy sources are necessary to reduce the U.S. dependence on foreign oil. Sorghum (Sorghum bicolor L.) may be a reasonable alternative as an energy crop in the southern U.S. because it could easily fit into existing production systems, it is drought resistant, and it has large biomass production potential. An experiment was conducted to evaluate several types of sorghum as bioenergy crops in Alabama: grain sorghum - NK300 (GS), forage sorghum - SS 506 (FS), and photoperiod sensitive forage sorghum - 1990 (PS). These sorghum crops were compared to forage corn (Zea mays L.) - Pioneer 31G65 in 2008 and 2009 with and without irrigation, and under conventional (total disked area, 0.15 m deep) and conservation tillage (in-row subsoiling, 0.30 m deep) in a strip-split-plot design. The parameters evaluated were: plant population (PP), plant height (PH), sorghum/corn aboveground dry matter (ADM), biomass moisture content (ABMC), and biomass quality (holocellulose, lignin, and ash). Sorghum had greater ADM than corn; however, corn had lower ABMC than sorghum. Lodging was observed in PS and FS, probably due to high plant populations (>370,000 plants ha⁻¹). Irrigation affected ADM positively in both years, but conservation systems improved ADM production only in 2009. Holocellulose, lignin, and ash variation differed significantly among crops but were lower than 8.3%, 2.0% and 1.9%, respectively, for both years and considered minor. Under conditions of this study, PS was considered the best variety for ADM production as it yielded 26.0 and 30.1 Mg ha⁻¹ at 18 and 24 weeks after planting (WAP).     

Allelopathic effects of Ambrosia artemisiifolia L. in the invasive process

Ambrosia artemisiifolia (common ragweed), an annual native to North America, is now present in many European countries where it causes summer hay fever and interferes with several important crops. We investigated if common ragweed invasiveness could be explained by its leaf tissue and root exudate allelopathic potential on indicator crops (alfalfa, barley, maize, lettuce, tomato, and wheat), weeds (Echinochloa crus-galli, Solanum nigrum, Portulaca oleracea, and Digitaria sanguinalis), and common ragweed itself in laboratory and greenhouse conditions. Different residue substrates were prepared for soil incorporation and trials were conducted under both laboratory (1, 2, and 3 g residues/Parker dish) and greenhouse conditions (1.28 g residues/pot). The effect of the preparations on the germination and growth of the indicator crops and weeds were evaluated relative to soil previously used to grow A. artemisiifolia. Results showed tomato was the most sensitive indicator crop species as growth was reduced by more than 50% in both laboratory and greenhouse experiments. Lettuce root and shoot growth were also inhibited, but only when common ragweed residues, and not root exudates, were added to the substrate. Among the weeds, E. crus-galli was not affected by common ragweed while D. sanguinalis suffered a large germination reduction (90%) after incorporation of 3 g of residues. If common ragweed occurred as weed in a field, the cultivation of a less sensitive crop such as winter wheat should be considered before the cultivation of a more susceptible crop.     

Host range,symptomology, and serology of isolates of potato virus Y (PVY) that share properties with both the PVYN and PVYO strain groups

In surveys for the tobacco veinal necrosis strain of potato virus Y (PVY^N) in potato, two isolates (I-136 and I-L56) were obtained that shared properties with both the PVY^N and the common (PVY^O) strain groups. The isolates produced veinal necrosis on tobacco (Nicotiana tabacum L.) and mild symptoms on potato (Solanum tuberosum L.) cv. Jemseg, typical of PVY^N but their symptoms on some other indicator species such asCapsicum frutescens L.,Chenopodium amaranticolor Coste & Reyn.),Physalis angulata L.,P. floridana Rybd. were more typical of PVY^O. Their serological properties were also more typical of PVY^O in that they reacted with a PVY^O-specific monoclonal antibody (MAb) in ELISA and they failed to react with four PVY^N-specific MAbs. The possible taxonomic position of these isolates is discussed.     

Effects of temperature and photoperiod on flowering time of forage legumes in a Mediterranean environment

Flowering time plasticity is a commonly occurring adaptive characteristic of fodder crops, including legumes, in arid and semiarid environments of the Mediterranean regions. Time of flowering is mainly influenced by genotype, temperature and photoperiod. Field experiments were carried out at Foggia (southern Italy) during successive growing seasons (from 8 to 16 growing cycles according to species) to study the relation among air temperature, photoperiod and duration of the morphological development of flowering in eight forage legume species: sulla (Hedysarum coronarium L.), sainfoin (Onobrychis viciifolia Scop.), pea (Pisum sativun L.), berseem clover (Trifolium alexandrinum L.), Persian clover (Trifolium resupinatum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.) and hairy vetch (Vicia villosa Roth). Time to reach 10% flowering (EF) and 100% flowering (FF) were recorded. Rate of progress to flowering, defined as the inverse of time from sowing to EF and FF, was related to mean daily temperature, or to both mean daily temperature and mean photoperiod. Using the linear equations, the thermal time requirements (T_t) and the base temperature (T_b) expressed as heat units were determined by the x-intercept method for both EF and FF stages. Evaluation of flowering time was also based on days after planting (DAP), day of year (DOY) and on a photothermal index (PTI). For all species, a significant negative correlation (P ≥ 0.01) was found between planting date (PD) and DAP whereas PTI showed a significant negative relationship (P ≥ 0.05) only for faba bean, pea, berseem clover and common vetch. In sainfoin, sulla and berseem clover, the rate of progress to flowering was affected significantly (P ≥ 0.05) by both mean temperature and photoperiod. The T_t requirements to reach the EF and the FF stage ranged from 871 to 1665 °C day and from 1043 to 1616 °C day, respectively, for the studied species. Both phenological stages considered depended upon accumulated thermal time above a species-specific base temperature. Furthermore, in all legumes the onset of flowering only occurred when dual thresholds of a minimum T_t and a minimum photoperiod were reached, which were specific to each species.     

Plant water stress at various growth stages and growth and yield of soybeans

In the Southern High Plains of the U.S.A., where water for irrigation is being depleted, drought-tolerant crops are extensively grown under limited irrigation where less water is applied than is required for potential evapotranspiration and maximum yield. This study was conducted (1) to determine the effects of plant water stress at various growth stages on growth and yield of soybeans [Glycine max (L.) Merr.] and (2) to assess the adaptability of the soybean plant to limited irrigation in the stressful climate of the Southern High Plains. The 3-year study was conducted on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). Soybeans (‘Douglas’, indeterminate, maturity group IV) were grown with different irrigation treatments designed to subject the plants to water deficits at different growth stages. Stress initiated during R1 (early flowering) or R2 (full bloom) and extending to R3 (beginning pod development) reduced seed yields by 9–13%. But, when stress was extended to R4.5, yields were reduced by 46%. Stress beginning at R3 and extending to R4.5 reduced yields by 19%. Stress imposed at R5 and relieved at R6 reduced yields 15% in one year and 46% in a more stressful year. Stress imposed at R5 and extending to the end of the growing period (5 weeks) reduced yields by 45% in the less-stressful year and by 88% in the other. Stress throughout the last 3 weeks of the growing period (beginning at R6) reduced yields by 21 and 65%, respectively, in the two years. Water-use efficiency was not increased under limited irrigation. Soybeans are amenable to limited irrigation under the stressful climate of the Southern High Plains, but their vulnerability to drought stress during seed development complicates management. They are more suited for limited irrigation than is corn (Zea mays L.) but are less suited than are grain sorghum [Sorghum bicolor (L.) Moench], cotton (Gossypium hirsutum L.) or wheat (Triticum aestivum L.).     

Sorghum (Sorghum bicolor L. Moench) contains a XIP-type xylanase inhibitor but none of the TAXI- and TLXI-types

A xylanase inhibitor of the xylanase-inhibiting protein (XIP) type was detected in sorghum (Sorghum bicolor L. Moench) whole meal using Western blot and immunoprobing with polyclonal anti-XIP antibodies. No detectable levels of Triticum aestivum xylanase inhibitor (TAXI) and thaumatin-like xylanase inhibitor (TLXI) type xylanase inhibitors were present. Trichoderma longibrachiatum xylanase affinity chromatography (AC) was used for the purification of sorghum XIP. Biochemical characteristics and protein sequence data show that sorghum XIP strongly corresponds to wheat (T. aestivum L.) XIP-I. Like wheat XIP-I, it inhibits both glycoside hydrolase family (GH) 10 and 11 xylanases, indicating that the XIP-I active site residues are well conserved in sorghum XIP. However, in contrast to wheat XIP-I, the inhibitor is unable to affect Aspergillus niger GH 11 xylanase activity. Its specific inhibition activities towards the other xylanases tested are comparable to those of wheat XIP-I. Based on the available sorghum expressed sequence tag (EST) database, XIP is expressed in sorghum in different tissues and developmental stages. Also expression in the presence of several plant hormones and under biotic as well as abiotic stress conditions is suggested.     

Biomass, extracted liquid yields, sugar content or seed yields of biofuel feedstocks as affected by fertilizer

Harvesting products from plants for conversion into renewable resources is increasing in importance. Determination of nutrition requirements for the applicable crops is necessary, especially in regions where the biofuel feedstock crops have not been historically grown. Sunflower (Helianthus annuus L.), two hybrids and one variety; sweet and grain (milo) sorghums (both Sorghum bicolor L.), one variety each, and sweet corn (Zea mays var. rugosa Bonaf.), four cultivars, were provided the recommended and twice the recommended rate of fertilizer. Biomass, expressed liquid volumes and sugar contents of sweet sorghum and sweet corn were determined. Grain yields of milo and sunflower and oil content of sunflower were determined. Sweet corn stalk sugar levels were below what is expected from field corn (maize), and were not affected by fertilizer rate. Sweet sorghum biomass and sugar content were within expected ranges and not affected by fertilizer rate. Milo grain yields were higher with increased fertilizer. Seed yield in Sunflower, which was below expected levels, was inconsistently affected by fertilizer rate, years or varieties. Overall crops year and cultivar/variety had more effect on results than did fertilizer. There does not appear to be a reason to provide fertilizer above recommended rates in production of these crops.     

Effects of aromatic plants incorporated as green manure on weed and maize development

A 2-year field experiment was conducted in northern Greece to study the mulch effects of seven annual [anise (Pimpinella anisum L.), sweet fennel (Foeniculum vulgare P. Mill.), sweet basil (Ocimum basilicum L.), dill (Anethum graveolens L.), coriander (Coriandrum sativum L.), parsley (Petroselinum crispum (P. Mill.) Nyman ex A.W. Hill) and lacy phacelia (Phacelia tanacetifolia Benth.)] and three perennial [mint (Mentha X verticillata L.), oregano (Origanum vulgare L.) and common balm (Melissa officinalis L.)] aromatic plants, used as incorporated green manure, on the emergence and growth of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], common purslane (Portulaca oleracea L.), puncturevine (Tribulus terrestris L.), common lambsquarters (Chenopodium album L.) and maize (Zea mays L.). In addition, the phytotoxic potential of the abovementioned aromatic plants extracts was determined in the laboratory using a perlite-based bioassay with maize and barnyardgrass. The bioassays indicated that germination, root elongation and fresh weight of barnyardgrass were reduced by the most aromatic plant extracts. However, maize growth parameters were only affected by the extracts of anise, sweet fennel, coriander, common balm and oregano. In the field, emergence of barnyardgrass, common purslane, puncturevine or common lambsquarters was reduced by 11–50%, 12–59%, 26–79% or 58–83% in green manure-treatment plots, respectively, as compared with green manure-free plots (control). On the contrary, maize emergence was not affected by any green manure. At harvest, maize grain yield in green manure-herbicide untreated plots was 10–43% greater than that in the corresponding green manure-free plots. In particular, maize grain yield in anise, dill, oregano or lacy phacelia green manure-herbicide untreated plots was 27–43% greater than that in the green manure-free-herbicide untreated and slightly lower than that obtained in the corresponding herbicide treated plots. These results indicated that green manure of aromatic plants, such as anise, dill, oregano or lacy phacelia could be used for the suppression of barnyardgrass and some broadleaf weeds in maize and consequently to minimize herbicide usage.     

A Survey of Woody Tropical Species for Boron Retranslocation

Abstract

The mobility in phloem of boron (B) has been reported to vary among plant species. Boron is phloem immobile in many species and completely mobile in others. Recent reports regarding phloem B mobility or immobility only considered temperate plants, and there is no information on tropical species. Information of phloem B mobility is useful for improving the diagnosis of B deficiency and management of B status in crop production. This study aimed to survey tropical species for their B mobility. Leaf samples of 17 species, including cashew (Anacardium occidentale L.), mango (Mangifera indica L.), custard apple (Annona squamosa L.), papaya (Carica papaya L.), cassava (Manihot esculenta Crantz.), Indian walnut (Samanea samen (Jacq.) Marrill.), cork wood tree (Sesbania grandiflora (L.) Pers.), tamarind (Tamarindus indica L.), jackfruit (Artocarpus heterophyllus Lamk.), guava (Psidium guajava L.), star fruit (Averrhoa carambola L.), passion fruit (Passiflora edulis Sims.), coffee (Coffea arabica L.), lime (Citrus aurantifolia Swingle.), longan (Euphoria longana Lam.), lychee (Lychi chinensis Sonn.) and teak (Tectona grandis L.) were collected in the position of the youngest fully expanded leaf (YFEL), the middle leaf age of a branch (ML) and the oldest leaf (OL). Based on a premise that the nutrient concentration gradient between young and old leaves will be steeper in those species in which B is immobile, B concentration in the different leaf positions was examined in comparison with calcium (Ca is phloem immobile) and potassium (K is phloem mobile). Concentrations of K in all leaf types were not significantly different or decreased with leaf age, while Ca concentrations were always higher in the older leaves. Three species; tamarind, guava and teak, showed concentration gradients of B that were similar to K. The results suggested that B may be retranslocated from older to younger leaves of these species, hence indicating that B may be phloem mobile in these species. However, this hypothesis needs confirmation through studies examining retranslocation of B using ¹⁰B isotope or identification of B-complexing molecules in the phloem, e.g. sugar alcohols.     

Energy Use Efficiency of Conventional versus Conservation Management Practices for Irrigated Potato Production in Southern Alberta

A 12-yr. (2000–2011) study was conducted in Alberta, Canada to compare the energy use efficiency (EUE) of conventional (CONV) and conservation (CONS) potato (Solanum tuberosum L.) management practices. Potato was grown in 3- to 6-yr. rotations which included dry bean (Phaseolus vulgaris L.), sugar beet (Beta vulgaris L.), soft wheat (Triticum aestivum L.), oat (Avena sativa L.), and timothy (Phleum pratense L.). CONS included compost application, reduced tillage, cover crops, and solid-seeded bean. Findings suggested that potato in 5-yr. CONS produced the highest EUE compared to the other CONS or CONV rotations. CONS can be used as a means of reducing the reliance on non-renewable energy inputs and improving overall EUE of potato production when less than 21% of the N content of compost applied was counted toward energy input use of potato production. At more than 21%, potato in the 4-yr. CONV became more favorable compared to potato in other rotations.