Manganese requirement of sunflower (Helianthus annuus L.), tobacco (Nicotiana tabacum L.) and triticale (x Triticosecale W.) at early stage of growth

Manganese deficiency symptoms are more often observed in crops at early stages of growth since Mn²⁺ can be easily mobilized from the surface soil. The objectives of this study were to evaluate some of the popular rotation crops grown in Hungary for tolerance to low external Mn²⁺ levels and to determine the critical tissue concentration for Mn²⁺ deficiency during early stages of growth. Indicator plants of sunflower (Helianthus annuus L.) were grown with NPKCaMg-fertilization induced of 0.0425–0.0700 g kg⁻¹; of tobacco (Nicotiana tabacum L.) 0.0237–0.0337 g kg⁻¹; of triticale (x Triticosecale W.) 0.0103–0.0327 g NH₄-acetate + EDTA extractable soil Mn²⁺ kg⁻¹; and were grown for 73, 50, and 191 days. The minimum Mn²⁺ concentration required in soil nutrient contents was 0.0425 g kg⁻¹ for sunflower, 0.0243 g kg⁻¹ for tobacco, and 0.0103 g kg⁻¹ for triticale. Sunflower, tobacco and triticale achieved optimum growth from 0.048 to 0.065 g Mn²⁺ kg⁻¹, from 0.0249 to 0.0321 g Mn²⁺ kg⁻¹, and from 0.0287 to 0.0296 g Mn²⁺ kg⁻¹, respectively. Critical ABP's dry weight Mn²⁺ concentration at early stages of growth was 0.0536 g kg⁻¹ in sunflower, 0.458 g kg⁻¹ in tobacco, and 0.1938 g kg⁻¹ in triticale. Our results demonstrate that the tolerance to low external Mn²⁺ (triticale <0.0302 g kg⁻¹; sunflower <0.0562 g kg⁻¹; tobacco <0.0693 g kg⁻¹) and the critical tissue Mn²⁺ levels for deficiency varied significantly among crop species tested.     

Growth and development of bambara groundnut (Vigna subterranea) in response to soil moisture: 2. Resource capture and conversion

A study was conducted in controlled environment glasshouses to investigate the effects of soil moisture on resource capture and conversion of three landraces (DipC, S19-3 and UN from Botswana, Namibia and Swaziland, respectively) of bambara groundnut (Vigna subterranea (L.) Verdc.). The study was conducted under two soil moisture treatments: an irrigated control and a drought treatment where irrigation was withheld from approximately flowering to final harvest. Drought reduced the mean fractional intercepted radiation (f) from 0.8 to less than 0.7 across landraces. The mean light extinction coefficient (=0.46) was not affected either by landrace or watering regime, while cumulative intercepted radiation (S_ci) reduced under drought because of the reduction in f. Drought reduced total transpiration (E_c) only in DipC while it had no effect on the other two landraces. Crops under irrigation extracted most of the water from the top 50 cm of the profile while those under drought extracted water down to 90 cm. The conversion coefficient for intercepted radiation (_s; g MJ⁻¹) was reduced by 32%, from 1.51 to 1.02 g MJ⁻¹. Similarly, drought reduced the dry matter/transpired water ratio (ε_w; g kg⁻¹) by 20% from 2.05 to 1.65 g kg⁻¹.     

Seed yield, oil and phytate concentration in the seeds of two oilseed rape cultivars as affected by different phosphorus supply

A greenhouse pot experiment was conducted for studying seed and oil yield, P uptake and phytate concentration in the seed of two oilseed rape cultivars (Brassica napus L. var. Oleifera, cv. Bristol and cv. Lirajet), grown on a soil substrate at different levels of plant available phosphorus (6, 19, 31 and 106 mg P-CAL kg⁻¹ soil, resp.). All other nutrients were maintained at a high level. At maturity, seed yield and seed quality were investigated. An increase in the phosphorus soil supply resulted in a significant (P<0.05) increase in seed and oil yield, oil and P concentration of the seeds, and P transported to the seeds. The phytate-phosphorus concentration ranged from 0.5 to 6.9 g kg⁻¹ in the seeds and from 0.9 to 12.8 g kg⁻¹ in rapeseed meal. Insufficient P supply resulted in a reduced concentration of phosphorus and phytate in the seeds. Significant interactions between the factors cultivar and P supply were found for the traits seed yield, oil yield, and P-harvest index.     

Water use and water use efficiency of cool season grain legumes in low rainfall Mediterranean-type environments

The water use (E_t) and water use efficiency (WUE) of a range of cool season grain legume species (field pea [Pisum sativum L.], faba bean [Vicia faba L.], chickpea [Cicer arietinum L.], lentil [Lens culinaris Med.], albus lupin [Lupinus albus L.], dwarf chickling [Lathyrus cicera L.], ochrus chickling [Lathyrus ochrus L.], grass pea [Lathyrus sativus L.], narbon bean [Vicia narbonensis L.], common vetch [Vicia sativa L.], and purple vetch [Vicia benghalensis L.]) were examined on fine textured neutral to alkaline soils in the low to medium rainfall Mediterranean-type environments in south-western Australia at Merredin and Mullewa in two seasons. There was no difference in the total E_t between grain legumes at either site in either year. There was also no variation in soil water extraction between species on the shallow sandy loam soil at Merredin. However, C. arietinum, L. sativus and L. cicera had greater water extraction and P. sativum the least water extraction at Mullewa where soil conditions were less hostile and root penetration was not restricted. The pattern of water use varied markedly between the grain legume species examined. Grain yield was positively correlated with post-flowering water use (E_tpa) in both erect (r=0.59) and prostrate (r=0.54) grain legume species. Water use efficiencies for dry matter production (WUE_dm) of up to 30 kg ha⁻¹ mm⁻¹ for V. faba and V. narbonensis at Merredin, and water use efficiencies for grain yield (WUE_gr) of up to 16 kg ha⁻¹ mm⁻¹ for P. sativum and 13 kg ha⁻¹ mm⁻¹ for V. faba at Mullewa, were comparable to those reported for cereals and other grain legumes in previous studies in this and other environments. Potential transpiration efficiencies (TE) of 15 kg ha⁻¹ mm⁻¹ together with soil evaporation (E_s) values of 100–125 mm were estimated in this and associated studies, and can be used as benchmark values to assess the yield potential of cool season grain legume crops in low rainfall Mediterranean-type environments. The major traits of adaptation for grain legume species producing large yields in this short season environment are early flowering, and pod and seed set before the onset of terminal drought. Early phenology together with rapid ground cover and dry matter production allows greater water use in the post flowering period. This leads to greater partitioning of dry matter into seed, which is reflected in greater harvest index (HI) and WUE_gr, as was observed for V. faba and P. sativum. Improvement in the adaptation of other grain legume species to short season Mediterranean-type environments requires increased early growth for rapid ground cover and improved tolerance to low temperatures (especially for C. arietinum) during flowering and podding.     

Influence of aqueous 1-methylcyclopropene concentration, immersion duration, and solution longevity on the postharvest ripening of breaker-turning tomato (Solanum lycopersicum L.) fruit

The influence of aqueous 1-methylcyclopropene (1-MCP) concentration, immersion duration, and solution longevity on the ripening of early ripening-stage tomato (Solanum lycopersicum L.) has been investigated. Tomato fruit at the breaker-turning stage were fully immersed in aqueous 1-MCP at 50, 200, 400 and 600 μg L⁻¹ for 1 min, quickly dried, and then stored at 20 °C. Ethylene production, respiration, surface color development, and rate of accumulation of lycopene and polygalacturonase (PG) activity were suppressed and/or delayed in fruit exposed to aqueous 1-MCP. Suppression of ripening was concentration dependent, with maximum inhibition in response to 1 min immersion occurring at concentrations of 400 and 600 μg L⁻¹. Climacteric ethylene peaks were delayed approximately 6, 7, and 9 d and respiration was strongly suppressed in fruit treated with aqueous 1-MCP at 200, 400, and 600 μg L⁻¹, respectively, compared with control fruit. Fruit firmness, lycopene content, PG activity, and surface hue of fruit treated at the three higher levels remained strongly suppressed compared with control. Skin hue values and pericarp lycopene content in response to treatment at the subthreshold 50 μg L⁻¹ provided evidence for differential ripening suppression in external versus internal tissues. Maximum delay of softening and surface color development in response to 50 μg L⁻¹ aqueous 1-MCP occurred following immersion periods of between 6 and 12 min. Factors affecting fruit penetration by aqueous 1-MCP and mechanisms contributing to recovery from 1-MCP-induced ripening inhibition are discussed.     

Tillage, cover crops, and nitrogen fertilization effects on soil nitrogen and cotton and sorghum yields

Sustainable soil and crop management practices that reduce soil erosion and nitrogen (N) leaching, conserve soil organic matter, and optimize cotton and sorghum yields still remain a challenge. We examined the influence of three tillage practices (no-till, strip till and chisel till), four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], vetch/rye biculture and winter weeds or no cover crop}, and three N fertilization rates (0, 60–65 and 120–130 kg N ha⁻¹) on soil inorganic N content at the 0–30 cm depth and yields and N uptake of cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench]. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) from 1999 to 2002 in Georgia, USA. Nitrogen supplied by cover crops was greater with vetch and vetch/rye biculture than with rye and weeds. Soil inorganic N at the 0–10 and 10–30 cm depths increased with increasing N rate and were greater with vetch than with rye and weeds in April 2000 and 2002. Inorganic N at 0–10 cm was also greater with vetch than with rye in no-till, greater with vetch/rye than with rye and weeds in strip till, and greater with vetch than with rye and weeds in chisel till. In 2000, cotton lint yield and N uptake were greater in no-till with rye or 60 kg N ha⁻¹ than in other treatments, but biomass (stems + leaves) yield and N uptake were greater with vetch and vetch/rye than with rye or weeds, and greater with 60 and 120 than with 0 kg N ha⁻¹. In 2001, sorghum grain yield, biomass yield, and N uptake were greater in strip till and chisel till than in no-till, and greater in vetch and vetch/rye with or without N than in rye and weeds with 0 or 65 kg N ha⁻¹. In 2002, cotton lint yield and N uptake were greater in chisel till, rye and weeds with 0 or 60 kg N ha⁻¹ than in other treatments, but biomass N uptake was greater in vetch/rye with 60 kg N ha⁻¹ than in rye and weeds with 0 or 60 kg N ha⁻¹. Increased N supplied by hairy vetch or 120–130 kg N ha⁻¹ increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds or 0 kg N ha⁻¹. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch/rye biculture cover crop and 60–65 kg N ha⁻¹. The results can be applied in regions where cover crops can be grown in the winter to reduce soil erosion and N leaching and where tillage intensity and N fertilization rates can be minimized to reduce the costs of energy requirement for tillage and N fertilization while optimizing crop production.     

Combustion quality of biomass: practical relevance and experiments to modify the biomass quality of Miscanthus x giganteus

A catalogue is set up describing the quality characteristics relevant for the combustion of biomass to be used as solid fuel. The practical relevance of these characteristics is discussed. The main characteristics are water concentration, the concentration of chloride and ash, the heating value and the concentration of volatiles and remaining coke. Further quality criteria are the concentrations of nitrogen, sulphur, potassium and calcium.

In multifactorial field trials at three locations, the influence of location, fertilizer application and harvest date on the quality of Miscanthus biomass from 3- and 4-year-old plantations was tested. The concentrations of water, minerals and ash, all three of which should be as low as possible, were higher in biomass from the cool and humid than in biomass from the warm location. The application of potassium fertilizer led to increases in the ash and potassium concentrations. Harvesting Miscanthus in February instead of December led to an improved biomass quality because the concentrations of ash, minerals and especially of water had declined.

Compared to other lignocellulose plants Miscanthus biomass has a very good combustion quality. In February the stems of Miscanthus had a water concentration of only 16–33%. The mineral concentrations were also low, with 0.3–2.1 g kg⁻¹ for chloride, 0.9–3.4 g kg⁻¹ for nitrogen and 3.7–11.2 g kg⁻¹ for potassium. © 1997 Elsevier Science B.V.     

Maximum slat width for cooling efficiency of horticultural produce in wooden crates

The influence of wood package design on airflow distribution was investigated for forced-air cooling using horticultural produce simulators. The position of grooves on the container walls was tested using slat width of 100–200 mm and airflow rates ranging from 0.0005 to 0.003 m³ kg⁻¹ s⁻¹. The package opening configurations were compared based on their impact on the energy added to the system using a methodology previously developed. For this purpose, apples and sweet corns were taken as examples of produce from two different extremes in the respiration activity range. For airflow rates as low as 0.0005 m³ kg⁻¹ s⁻¹one groove at the bottom of the container produced a cooling process more uniform than the other one-groove configurations and even two grooves because of natural convection effect. If packing low respiration rate produce, increasing airflow rate could compromise the process energy efficiency because of air circulation obstruction for less vented containers. For high respiration rate produce enlarging open area above 2.4% would be recommended rather than increasing airflow rate to enhance cooling energy efficiency.     

The effect of breeding on the phenology of Italian durum wheats: From landraces to modern cultivars

An understanding of the changes in phenology resulting from durum wheat breeding in Italy can inform breeding objectives for durum wheat improvement in Mediterranean environments. The phenology of a set of 20 durum wheat cultivars, grouped according to their period of release into ‘old’, ‘intermediate’ and ‘modern’, was compared in two sowings (September and May) with or without artificial vernalization. The vernalization treatment and the 6 h range in daylength and wide variation in temperature were responsible for the variation in anthesis date from 817 to 2105 °Cd (base 0 °C) from sowing. Old cultivars had the greatest photoperiod sensitivity and cold requirement, intermediate ones the greatest earliness per se and modern ones the least photoperiod sensitivity and greatest earliness per se. The first substantive effect of breeding in Italy on phenology was achieved with introgression from syriacum germplasm, which increased earliness both by an increase in earliness per se and a reduction in photoperiod sensitivity. The next step, characterized by the introduction of the semi-dwarfing gene Rht1, had a specific effect of reducing photoperiod sensitivity, although the modern group of varieties has a relatively low level of earliness per se, which is fundamental for preserving and increasing the length of the TS-anthesis period. Some quantitative cold requirement still persists in Italian germplasm, although all the cultivars tested are classified as spring types. The main phenological events affected by the changes in anthesis date resulting from breeding depend on the mechanism involved. Variability among cultivars within each group is also described.     

Biomass yield and energy balance of giant reed (Arundo donax L.) cropped in central Italy as related to different management practices

In order to evaluate the possibility of reducing energy input in giant reed (Arundo donax L.) as a perennial biomass crop, a field experiment was carried out from 1996 to 2001 in central Italy. Crop yield response to fertilisation (200–80–200 kg ha⁻¹ N–P–K), harvest time (autumn and winter) and plant density (20,000 and 40,000 plants per ha) was evaluated. The energy balance was assessed considering the energy costs of production inputs and the energy output obtained by the transformation of the final product. The crop yield increased by +50% from the establishment period to the 2nd year of growth when it achieved the highest dry matter yield. The mature crop displayed on average annual production rates of 3 kg dry matter m⁻², with maximum values obtained in fertilised plot and during winter harvest time.

Fertilisation mainly enhanced dry matter yield in the initial period (+0.7 kg dry matter m⁻² as years 1–6 mean value). The biomass water content was affected by harvest time, decreasing by about 10% from autumn to winter. With regard to plant density, higher dry matter yields were achieved with 20,000 plants per ha (+0.3 kg dry matter m⁻² as years 1–6 mean value).

The total energy input decreased from fertilised (18 GJ ha⁻¹) to not fertilised crops (4 GJ ha⁻¹). The higher energetic input was represented by fertilisation which involved 14 GJ ha⁻¹ (fertilisers plus their distribution) of total energy costs. This value represents 78% of total energy inputs for fertilised crops.

Giant reed biomass calorific mean value (i.e., the calorific value obtained from combustion of biomass sample in an adiabatic system) was about 17 MJ kg⁻¹ dry matter and it was not affected by fertilisation, or by plant density or harvest time. Fertilisation enhanced crop biomass yield from 23 to 27 dry tonnes per ha (years 1–6 mean value). This 15% increase was possible with an energy consumption of 70% of the overall energy cost. Maximum energy yield output was 496 GJ ha⁻¹, obtained with 20,000 plants per ha and fertilisation. From the establishment period to 2nd–6th year of growth the energy production efficiency (as ratio between energy output and energy input per ha) and the net energy yield (as difference between energy output and energy input per ha) increased due to the low crop dry biomass yield and the high energy costs for crop planting. The energy production efficiency and net energy yield were also affected by fertilisation and plant density. In the mature crop the energy efficiency was highest without fertilisation both with 20,000 (131 GJ ha⁻¹) and 40,000 plants per ha (119 GJ ha⁻¹).