Autumn Sowing Research Articles

Contribution of a herb and clover mix to spring and autumn sown forage for dryland dairying

This study investigated companion crops and time of sowing of a herb (chicory and plantain) and clover (red and white clover) mix in dairy pasture systems. Five summer crops (turnip, rape, turnip-rape, radish and millet), sown alone or in combination with herb/clover in spring 2003, were compared over the first summer. Dry matter (DM) production was higher for millet and rape than turnip-rape or radish. Metabolisable energy (ME) content of millet and turnip was lower, and neutral detergent fibre (NDF) content of millet higher than all other crops. Inclusion of herb/clover reduced ME and increased NDF at the second grazing. In autumn 2004, an Italian ryegrass + herb/clover mix was direct drilled into plots without the spring sown herb/clover mix, and Italian ryegrass only into the remaining plots. The spring sown herb/clover system resulted in higher herbage DM at the first grazing (June 2004) after sowing Italian ryegrass, but lower production in spring 2004 than the autumn sown herb/clover system. There were no differences in DM production at any other grazings. In winter and spring 2004, ME was higher for autumn than for spring sown herb/clover. Crude protein content was higher for autumn sown herb/clover in June and July than for spring sown, but lower from December 2004 to April 2005. From September 2004 to August 2005, the NDF content of spring sown herb/clover was lower than for autumn sown. Throughout the study, both chicory and plantain content (%DM) was higher and weed and dead matter lower, with spring compared to autumn sowing. Keywords: herbage production, chicory, plantain, metabolisable energy, weed suppression

Assessing various rehabilitation strategies for coarse coal washery reject dumps in the Hunter Valley, Australia. I. Chemical characteristics

At several coal mines in the Hunter Valley (New South Wales, Australia), the use of coarse coal washery reject (chitter) as a top-dressing material has resulted in successful establishment rates of tree and shrub species by direct seeding. However, concerns have arisen about the potential to downgrade the rural capability of the land for grazing, poor understanding of the material's long-term benefits, and spontaneous combustion issues. To ascertain the suitability of chitter as a final landform surface, a revegetation research trial was initiated at United Collieries coal mine in the Hunter Valley of New South Wales. Experimental plots were established in autumn (May 1998) and spring (November 1998) on a freshly shaped stockpile of chitter. The revegetation trials incorporated four substrate treatments, namely a 1 m and 20 cm capping of overburden, a 20 cm topsoil dressing and a treatment of only chitter. Each of the four substrate treatments incorporated five revegetation treatments, namely pasture species and mulch (straw), pasture species and no mulch, native seed (shrub and tree) and mulch, native seed and no mulch, and planted tubestock trees. Chemical characteristics (pH, EC, total N, nitrate-N, available-P, total P, total S, Ca, Na, Mg, K, organic C and soil moisture) across the substrate and vegetation treatments were assessed at 0, 3, 6 and 12 months after establishment. Laboratory analyses of soil samples from the autumn and spring substrate sowings concluded that the chitter treatment contained a significantly higher concentration of organic carbon (23 – 41%), Na (2.8 – 13 me/100g), total N (2600 – 5300 mg/kg) and S (900 – 4000 mg/kg), and pH was elevated (7.5 – 9.8), relative to the other substrates. The topsoil substrate had significantly greater moisture content and more nitrate-N in comparison to the overburden and chitter materials, and exhibited a significantly lower pH over time. The two overburden treatments showed similar chemical properties and contained significantly higher levels of available P relative to topsoil and chitter. In comparison to recommended levels, all substrates recorded adequate levels of Ca, Mg and K across the autumn and spring assessments and were generally deficient in nitrate-N. In the overburden materials, levels of organic carbon, electrical conductivity, exchangeable bases, total P and available P were generally adequate. However, the pH (8.1 – 8.9) and S (200 – 700 mg/kg) content of overburden was consistently high, and deficiencies in total and available nitrogen were commonly detected. Assessment of substrate samples across vegetation treatments showed few differences with only K, available P and nitrate-N varying significantly between treatments. In both the autumn and spring trials, the concentration of available P in pasture plots was significantly higher in comparison to the other vegetation treatments, while K levels were significantly higher in the pasture and mulch treatment relative to tubestock plots. This probably resulted from greater uptake of these nutrients by trees and shrubs compared to pasture species. In the autumn trials, seeded native tree plots contained significantly more nitrate-N than the other treatments, probably due to N-fixation by Acacia spp. Across both establishment seasons, topsoil provided the best chemical substrate for the establishment of vegetation and chitter was deemed the least hospitable substrate, while the different vegetation treatments appeared to have little effect on the chemical characteristics of the substrates. Vegetation characteristics across the treatments are presented in an accompanying paper (Charnock and Grant, Assessing various rehabilitation strategies for coarse coal washery reject dumps in the Hunter Valley, Australia. II. Vegetation characteristics. International Journal of Surface Mining, Reclamation and Environment, 2005 (in review)).

The response of autumn and spring sown sugar beet ( Beta vulgaris L.) to irrigation in Southern Italy: Water and radiation use efficiency

The Apulia region in Southern Italy is an important area for sugar beet cultivation. It is characterised by clay soils and a hot-arid and winter-temperate climate. The capability of sugar beet to exploit solar radiation, water use and irrigation supply in root yield, total dry matter and sucrose production was studied and analysed in relation to two experimental factors: sowing date – autumn (October–December) and spring (March) – and irrigation regime – optimal and reduced (respectively with 100 and 60% of actual evapotranspiration). Data sets from three experiments of spring sowing and three of autumn sowing were used to calculate: (1) water use efficiency in the conversion in dry matter (WUE dm, plant dry matter at harvest versus seasonal water use ratio), in sucrose (WUE suc, sucrose yield versus seasonal water use ratio); (2) irrigation water use efficiency in the conversion in dry matter (IRRWUE dm), in sucrose (IRRWUE suc) and fresh root yield (IRRWUE fr); and (3) radiation use efficiency (RUE, plant dry matter during the crop cycle and at harvest versus intercepted solar radiation ratio). Autumnal beet was more productive than spring for fresh root, plant total dry matter, sucrose yield and concentration; also WUE suc and IRRWUE s were higher in the autumnal sugar beet, but no difference was observed in WUE dm (on average, 2.83 g of dry matter kg −1 of water used). An average saving of about 26% of seasonal irrigation supply (equivalent to about 100 mm) was measured in the three years with the earliest sowing time. The optimal irrigation regime produced higher root yield, plant total dry matter and sucrose yield than the reduced one; on the contrary the IRRWUE fr and IRRWUE dm were higher in the reduced irrigation strategy. WUE s and IRRUWE s correlated positively with the length of crop cycle, expressed in growth degree days and, in particular, to the length of the period from full soil cover canopy to crop harvest, the period when plant photosynthetic activity and sucrose accumulation are at maximum rates. Seasonal RUE was higher in the spring than in the autumn sowing (1.14 μg J −1 versus 1.00 μg J −1). The RUE values during the crop cycle reached the maximum in the period around complete canopy soil cover. The results showed the importance for better use of water and radiation resources of autumnal sowing time and of reduced irrigation regime in sugar beet cropped in a Mediterranean environment.

Establishment of native and exotic grasses on mine overburden and topsoil in the Hunter Valley, New South Wales

Native grasses have an important role to play in mine rehabilitation throughout Australia, but there have been few scientifically designed studies of field establishment of native grasses from sown seed in this country. Current recommendations for rehabilitation of open-cut coal mines in the Hunter Valley involve the sowing of exotic pasture species to reinstate mined land to Class IV and V under the Rural Land Capability System. Despite the importance of native grasses in the pre-mined landscape, they are currently not widely included in mine rehabilitation. To address this issue a project was conducted between 1994 and 2000 to research the use of native grasses for rehabilitation of open-cut coal mines in the Hunter Valley. This paper reports on 2 mine site experiments that aimed to assess establishment and persistence of a broad range of native and exotic grass species from an autumn sowing in both topsoil and raw spoil over a period of 61 months. The most promising natives in terms of early establishment, persistence and spread over time, included six C3 accessions (five Austrodanthonia spp. and Austrostipa bigeniculata) and one C4 accession (Cynodon dactylon). Persistence of these accessions was better in raw spoil than topsoil, despite initial low numbers, due to a lack of weed competition and their ability to spread by self-seeding. In topsoil, and in the absence of any biomass reduction, native species were mostly out-competed by vigorous exotic perennial grasses which were sown in these experiments and from seed influx from adjacent rehabilitation areas or from the soil seed bank. The effects of climatic conditions and differences in soil physical, chemical and seed bank characteristics at the 2 mine sites are also discussed.

Establishment and summer survival of the perennial legumes, Dorycnium hirsutum and D. rectum in Mediterranean environments

The genus Dorycnium has been identified for its potential use as a forage plant for southern Australia, but little is known about factors affecting establishment and survival. This investigation examined some factors affecting the establishment of D. hirsutum and D. rectum in Mediterranean environments of south-west Western Australia. The population dynamics of D. hirsutum and D. rectum seedlings were investigated during the summer drought in 4 environments. The effect of time of sowing on establishment and survival of D. hirsutum was tested as a management option for improving establishment of these species. Poor seedling performance was observed in both Dorycnium species. Less than 20% of D. rectum plants survived the summer drought at all locations, compared with >50% for D. hirsutum seedlings. Poor seedling vigour coupled with weed competition resulted in low plant numbers at 2 sites. Compared with autumn sowings, populations of D. hirsutum sown in August and September had lower plant densities before summer due to poorer seedling emergence. Plant numbers declined during the summer in all plots, but losses were greatest in those sown in September. In both experiments, small D. hirsutum plants survived in plots where little competition was present. Improvements in seedling vigour may be possible with plant breeding but establishment methods that reduce weed competition are valuable. Spring sowing may enable effective weed control before seeding, but later sowings run the risk of reducing seedling emergence and survival.

Recognition of Drainage Improvement at Converted Lands by Using Aerial Photographs : A Case Study of Autumn Sowing Wheat

Recognition of Drainage Improvement at Converted Lands by Using Aerial Photographs : A Case Study of Autumn Sowing Wheat

Effects of natural reseeding and establishment method on contamination of a novel endophyte‐infected perennial ryegrass dairy pasture with other ryegrass/endophyte associations

The contamination of a perennial ryegrass (Lolium perenne) dairy pasture infected with a novel endophyte with other ryegrass/endophyte associations was studied over 2 years in Hamilton, New Zealand. Five management treatments (turnip crop, usual rotational grazing, usual rotational grazing followed by topping, silage making, hay making) were applied to produce a range of natural reseeding levels, and then three establishment methods (spray/cultivation, double‐spray/fallow, hard‐grazing) were used before drilling AR1 endophyte‐infected perennial ryegrass (no lolitrem B or ergovaline production). Contamination from wild endophyte (Neotyphodium lolii)‐infected perennial ryegrass, endophyte‐free perennial ryegrass, wild endophyte‐infected hybrid (L. boucheanum syn. L. hybridum)/Italian ryegrass (L. multiflorum), N. occultans endophyte‐infected hybrid/Italian ryegrass and endophyte‐free hybrid/Italian ryegrass tillers was determined. Contamination was assessed in the two summers following the autumn (May 2000) sowing by measuring lolitrem B concentration in bulk ryegrass samples and by sampling individual ryegrass tillers for endophyte identification in late summer of Year 1. Within the hard‐grazed establishment treatment, the percentage of ryegrass tillers infected with AR1 in late summer of Year 1 was highest (73%) following the turnip crop pre‐sowing treatment and lowest (4%) after hay making (SED = 5.3%, P < 0.001). The percentages of AR1‐in‐fected perennial ryegrass tillers in pastures established following spray/cultivation and double‐spray/ fallow treatments were 86 and 76%, respectively, compared with only 15% in the hard‐grazed treatment (SED = 2.5, P < 0.001) (turnips excluded). The spray/cultivation and double‐spray/fallow establishment treatments consistently had lower concentrations of lolitrem B in bulk ryegrass samples than the hard‐grazed treatment, for example in early autumn of Year 1 (0.3, 0.5, 1.1 mg kg−1 DM, P < 0.001) and Year 2 (0.1, 0.2, 1.0 mg kg−1 DM, P < 0.001). Pasture production from August 2000 to August 2001 was similar following the spray/cultivation, double‐spray/fallow and hard‐grazed establishment treatments, averaging 14.9t DM ha−1. It is recommended that ryegrass pastures containing a novel endophyte be sown after a summer crop, or following a spray/ cultivation or double‐spray/fallow establishment method, instead of under‐sowing into existing hard‐grazed pasture. Methodology for assessing pasture contamination with different ryegrass/endophyte associations is also discussed.

Management of Galega officinalis L. and preliminary results on its potential for milk production improvement in sheep

Galega officinalis L. is a leguminous perennial herb that presents a demonstrated lac‐togenic effect. However, it is toxic to the ewe if it is eaten in substantial amounts, due to the presence of some alkaloids. The objective of this work was i) to optimise its management on Mediterranean‐type climate regions, and ii) to determine if controlled amounts of G. officinalis could increase milk yield in “Churra” ewes, without toxicity problems. The high level of specificity of the infective rhizobia makes it necessary to inoculate plants with selected strains, prior to the cultivation of G. officinalis. The optimum stand was 160 000 plants ha−1 obtained after broadcast autumn sowing, which in Mediterranean‐type climatic conditions increased yield in the first cutting year. Optimum cutting height was between 6 and 10 cm above ground level. The maximum yield was 13 t dry matter ha−1 in the first year, and 10 in the second year which allowed five cuttings per year before flowering. This avoids an increase in alkaloids at flowering. To increase the yield during the second year, delaying of the last cutting to avoid autumn regrowth is proposed. This cut would be left as green manure. Preliminary results on increasing milk yield indicated that a controlled daily dose of 2 g dry matter kg−1 (body weight) from the first month after lambing until the third milk recording 60 days later, led to a 16.90% increase in total milk yield and a 10.86% increase when the milk yield is readjusted to a lactation length of 120 days.

Effects of the erect/bushy habit, single/double pod and late/early flowering genes on yield and seed size and their stability in chickpea

The development of ascochyta blight resistant chickpea lines has allowed autumn sowing of this crop, and increased seed yields as result of higher biomass production than the traditional spring sowing in the Mediterrranean region. A second step in the chickpea yield improvement could be to increase harvest index. In this sense, the effect of the erect/bushy habit, single/double pod and late/early flowering genes on yield and seed size and their stability was studied using eleven F 6:7 ascochyta blight resistant chickpea lines. These lines were derived from a cross between an erect, single podded and late flowering line and a bushy, double podded early line. Six lines out of eleven were erect and late flowering (three being single and three double podded), two were single podded, bushy and late flowering, two double podded, bushy and early flowering, and finally one single podded, bushy and early flowering. A multilocation trial during four and 3 years under autumn and spring sowing, respectively, in the south of Spain was performed for yield and seed size. The stability of these lines was studied by AMMI analysis. Our results suggest that the double pod gene has no effects on both yield and seed size, although, confers a higher yield stability than the single pod gene. The mean yield of the lines with bushy growth habit, across all environments, was higher than that of the erect habit lines; 208.1 and 179.8 g/m 2 in autumn and 120 and 101.4 g/m 2 in spring sowing, respectively. Mean yield of the early lines, across all environments was higher than that of late lines; earliness was more important under spring sowing with yields of 130.2 and 102.3 g/m 2 for early and late lines, respectively. Thus, for developing new chickpea cultivars under Mediterranean conditions, breeding programs should consider that (i) for spring sowing, early flowering and bushy types are the characters with greater influence on yield and yield stability, respectively, and (ii) for autumn sowing, the important characters are bushy habit on yield and double pod and earliness on yield stability.

Eruca sativa spp. oleifera: a new non-food crop

The use of oil with a high level of erucic acid in some industrial sectors appears to offer excellent prospects from a technological and environmental point of view. This study was carried out to determine the potential of a new Eruca sativa spp. oleiformis selection named Nemat as a source of high erucic oil in the Po Valley environment. This species, classified as catch crop of the nematode Heterodera schachtii, showed a wide adaptability both in spring and autumn sowing and permitted a generally satisfactory productive yield over 3-year trials, with a grain yield ranging between 1.9 and 2.2 t ha −1 (autumn sowing). Seeds presented an oil concentration around 290 g kg −1 with significant higher amount in spring sowing, while fatty acid composition was characterised by a long chain content higher than 53%. The residual meal presented a high level of thiofunctionalised glucosinolates (GLs), showing some interesting perspectives in integrated pest management.

Establishing winterfat in prairie restorations in Saskatchewan

The importance of native shrubs in the Northern Mixed Prairie of Canada has generally been overlooked; however, restoration specialists have recognized the importance of including shrubs in prairie restorations. Emergence and establishment of winterfat (Krascheninnikovia lanata (Pursh) A. D. J. Meeuse &amp; Smit), a palatable and long-lived shrub, was evaluated in relation to planting time and seedbed preparation in swards of native grasses that had been seeded on previously cultivated cropland in the prairie ecozone of southern Saskatchewan. Diaspores of winterfat were broadcast at 20 m-2 in autumn or spring on upland and lowland sites in seedbed treatments including (1) a control or undisturbed sward, (2) mowing the sward to a 15-cm height, (3) haying, (4) glyphosate application after haying and, (5) tillage. Emergence of winterfat on upland and lowland sites was about three-fold greater with autumn than with spring planting (P &lt; 0.01). Winterfat establishment on upland sites was affected by the interacting influences of planting times and seedbed treatments (P = 0.01), with most winterfat establishing from autumn sowing in the glyphosate and tillage treatments (2.1 and 2.2 plants m-2, respectively). Establishment of 0.9 plants m-2 from autumn planting was greater (P &lt; 0.01) than the 0.1 plants m-2 establishing from spring sowing on lowland sites. The interaction of planting date and seedbed treatment on lowland sites did not influence winterfat establishment (P = 0.06) nor did seedbed treatments (P = 0.07). Winterfat should be planted in late autumn as opposed to spring. Key words: Ceratoides lanata, Eurotia lanata, Krascheninnikovia lanata, Northern Mixed Prairie, restoration

Identification of Quantitative Trait Loci (QTLs) Controlling Heading Time in the Population Generated from a Cross between Oriental and Occidental Barley Cultivars (&lt;i&gt;Hordeum vulgare&lt;/i&gt; L.)

The present study was carried out to identify QTLs controlling heading time of barley. A total of 89 recombinant inbred lines (RILs) generated from a cross between the Oriental-type winter cultivar ‘Azumamugi’ and the Occidental-type spring cultivar ‘Kanto Nakate Gold’ were examined. Two field experiments consisting of one spring sowing and one autumn sowing and a greenhouse experiment under 24 h illumination were conducted. Two genes for the spring habit and five QTLs controlling heading time were identified. The two genes for the spring habit, sgh1 and Sgh2 were located on chromosomes 4HL and 5HL, respectively; four QTLs were mapped close to the heading time genes identified in the previous studies on chromosomes 1HL, 2HS, 2HL and 7HS; and one was a new QTL detected on chromosome 7H.

Prospecção de zonas potenciais para manejo diferenciado em agricultura de precisão utilizando-se padrões de solo-planta-clima

A agricultura de precisão contempla a aplicação da informação tecnológica aos processos produtivos. A implementação de programas nesta linha depende da integração de dados de solo, planta e clima, para a geração de informações úteis. O reconhecimento de padrões em propriedades de solo e planta, é fundamental para a viabilização de práticas nessa área, principalmente para uma abordagem de lavouras por zonas ou classes de manejo. Visando estudar aspectos do delineamento de zonas potenciais para manejo diferenciado e distribuição espacial do potencial produtivo, conduziu-se um experimento na região de Angatuba, SP, Brasil. Uma amostragem intensiva de variáveis de solo e planta, além de dados do microclima, foi realizada em uma área de 40 ha cultivados com milho-sequeiro, em duas safras seguidas, além da integração dessas informações para o reconhecimento de padrões de solo e definição de zonas potenciais de manejo. Também se fez a verificação conjunta com os padrões de distribuição da malha de produtividade, durante duas estações de crescimento de milho-sequeiro. O processo de segmentação utilizado mostrou-se adequado para o delineamento proposto, ao mesmo tempo em que foi observado que a definição de zonas com potencial para manejo diferenciado é um processo dinâmico, podendo ser influenciado por propriedades do meio e condições climáticas.

Influence of Sowing and Harvest Time on Fibre Flax (Linum usitatissimum L.) in the Mediterranean Environment

AbstractTriennial field trials were carried out at Viterbo, central Italy, to investigate the influence of the sowing time, nitrogen fertilization and harvest dates of the two fibre flax (Linum usitatissimum L.) varieties Belinka and Ariane. Our results showed that warm and dry weather conditions, prevailing from late spring onwards, caused excessive shortening of the growing cycle of spring crops, with negative consequences for seed and fibre yield and quality. However, autumn sowings gave interesting results. Stem dry weight ranged between 5.6 and 6.7 t ha−1 for autumn sowings and between 1.9 and 4.1 t ha−1 for spring sowings. In autumn sowings, plant height and seed yields were also increased. Seed germinability was good even for early harvest dates. Stem dry weight remained constant at harvest dates following yellow‐green ripening, indicating that biomass was no longer allocated to the stems after that phase.

Crop and Weed Growth in a Sequence of Spring Barley and Winter Wheat Crops Established Together from a Spring Sowing (Relay Cropping)

AbstractA relay cropping system of cereals, whereby winter wheat (Triticum aestivum L.) was undersown in two‐row spring barley (Hordeum distichum L.), was established in a field trial in central Sweden in 1999 and continued until 2000. The purpose of the study was to examine crop and weed responses to different plant densities of the undersown winter crop. Winter wheat was sown at four seed rates (187, 94, 47 and 0 kg ha−1) immediately after the sowing of barley. Barley was harvested in the first autumn after sowing and winter wheat in the second autumn. The grain yield of barley was not affected by the seed rate of wheat, and averaged 4580 kg ha−1. Winter wheat did not vernalize during the first growing season but remained at the vegetative stage. The grain yield of wheat was 1990 kg ha−1 for the lowest and 5610 kg ha−1 for the highest seed rate of wheat. Whilst the undersowing process itself stimulated weed emergence in this experiment, increasing the undersowing seed rate reduced the population of perennial weeds by 40–70 %. In the second growing season, the total biomass of weeds was 66 % higher at the highest seed rate compared with the lowest seed rate.

Physiological nature of overwintering oats forms

We evaluated the need for low temperatures (vernalization) and the photoperiodic reaction of three collections of winter oats (1. Pedarn, Maris Quest, Peniarth; 2. Gerald, Solva, Kymon, Pendragon; 3. Pewi, Silwi, Wiskas) in a&amp;nbsp;comparison with spring oats varieties. All three collections of varieties showed little need for low temperatures, mostly as few as 10&amp;ndash;20 days, which does not represent an obligatory need; this influence is only quantitative and constitutes no precondition for a&amp;nbsp;passage of plants into the generative stage. Only in the case of the Maris Quest variety, the need for vernalization approached 30 days. As compared with the reaction of winter barley varieties that had and in some cases still have worse overwintering in the Czech Republic, the length of vernalization is equal. In the photoperiodic experiment, the reaction to a&amp;nbsp;short autumn day turned out to be the critical condition for a&amp;nbsp;possibility of autumn sowing and overwintering; in the case of these varieties, a&amp;nbsp;short day inhibits the development until arrival of winter. We evaluated this reaction according to the length of the induction period. This period was only 10&amp;ndash;15 days in the case of the spring oats Česk&amp;yacute; žlut&amp;yacute;, 30 days in the case of winter oats Maris Quest, 25 days for Pedarn, 20 days for Peniarth and 21 days for Pendra-gon; the induction period was 14&amp;ndash;21 days in the case of varieties Gerald, Kymon and Solva. When compared with figures for winter barley, it had the longer photoperiodic induction period. The evaluated varieties of winter oats do not reach such a&amp;nbsp;degree of a&amp;nbsp;reaction to a&amp;nbsp;short day, which manifests itself in their lower frosthardiness than that of winter barley. We verified that in provoking tests for frosthardiness, and also by lower critical values of temperatures for dying out of 50% of plants, the so-called LT 50.

Germination and establishment of halophytes on brine‐affected soils

Summary Contamination of soils with oilfield brines is a significant environmental problem in many oil‐production areas. This study tested the feasibility of using different salt‐accumulating halophyte species to remediate brine‐contaminated soils at a site in south‐eastern Ohio, USA, and tested whether planting season affected the germination, yield and sodium uptake of selected species. Atriplex prostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina and Suaeda calceoliformis were sown in October 1992 (autumn sowing) and March 1993 (spring sowing). For A. prostrata and Spergularia marina, spring‐sowing produced greater germination and survival, while H. jubatum exhibited greater germination and survival in autumn sowings. Germination and survival of Salicornia europaea and Suaeda calceoliformis were not significantly affected by sowing season, but Salicornia europaea germinated and survived poorly in both seasons. Spring‐sown A. prostrata and Suaeda calceoliformis and autumn‐sown H. jubatum and Spergularia marina produced the greatest yields. High soil conductivities negatively affected the survival and yield of spring‐sown A. prostrata, H. jubatum and Spergularia marina, but did not significantly affect autumn sowings. Root biomass allocation was greater in autumn‐sown H. jubatum, Spergularia marina and Suaeda calceoliformis. We hypothesized that autumn‐sown seeds of these species have earlier root development that facilitates avoidance of extreme salinity and moisture fluctuations found at the soil surface. All species accumulated higher amounts of Na+ and Cl− than other ions. Autumn‐sown A. prostrata and Suaeda calceoliformis accumulated significantly more Na+ than when spring‐sown. Ash content (a measure of accumulated inorganic matter) ranged from 15% to 35% in the various plant tissues. Hordeum jubatum had significantly more Na+ in its roots than in its shoots, making it less suitable for site remediation than A. prostrata or Suaeda calceoliformis. With the exception of Salicornia europaea, all species reduced soil salinity significantly compared with paired control plots, ranging from 4% in H. jubatum to 17% in A. prostrata. Leaching following precipitation resulted in a 44% reduction in Na+ from control plots over a 4‐year period. However, there was a 59% reduction in Na+ from plots vegetated with halophytes over the same period. The results indicate that establishment of salt‐accumulating halophytes on salt‐affected sites can sufficiently remediate the soil to the point where it can be returned to agricultural productivity or where native plants can invade and become established. The phytoremediation process can be facilitated by tailoring plant selection to site conditions, using inputs of fertilizer and water to enhance the growth of the halophytes, and by harvesting the plants on a regular basis.

Post‐war changes in arable farming and biodiversity in Great Britain

Summary Agriculture represents the dominant land use throughout much of western Europe, and a significant part of European biodiversity is associated with this habitat. We attempted to quantify the changes in agriculture and biodiversity in Britain since the 1940s. There have been widespread declines in the populations of many groups of organisms associated with farmland in Britain and north‐west Europe. The declines have been particularly marked amongst habitat specialists; many of the taxa still common on farmland are habitat generalists. Farming practices have become increasingly intensive in the post‐war period, with a dramatic reduction in landscape diversity. Since 1945, there has been a 65% decline in the number of farms, a 77% decline in farm labour and an almost fourfold increase in yield. Farms have become more specialized; the greatly increased use of machinery has made operations quicker and more efficient, but has resulted in the removal of 50% of the hedgerow stock. Autumn sowing of crops has become predominant, with winter stubbles now far less prevalent. The number and extent of chemical applications has increased greatly, but the net amount applied, and their persistence, has decreased in recent years. Intensification has had a wide range of impacts on biodiversity, but data for many taxa are too scarce to permit a detailed assessment of the factors involved. Reduction in habitat diversity was important in the 1950s and 1960s; reduction in habitat quality is probably more important now. As a case study, the declines in populations of seed‐eating birds populations were assessed in relation to changing agricultural management. Generally, the declines were likely to be caused by a reduced food supply in the non‐breeding season, although other factors may be important for particular species. Agriculture will face a number of challenges in the medium term. While research into the mechanisms underlying species and habitat associations, and their interaction with scale, will be critical in under‐pinning management, consideration of farmer attitudes and socio‐economic factors is likely to be as important. Biodiversity may benefit from integrated farming techniques but these need to incorporate environmental objectives explicitly, rather than as a fringe benefit.

Effect of autumn and winter mycorrhizal cover crops on soil properties, nutrient uptake and yield of sweet corn in Pennsylvania, USA

We investigated the effects of an autumn sowing of contrasting cover crops (oats, rye and a combination of oats and rye) on soil aggregate stability, mycorrhizal colonization, phosphorus uptake and yield of sweet corn planted the following summer. Rye is a common cover crop in the middle Atlantic region of the United States of America. It grows slowly in the autumn, survives the winter, grows rapidly in the spring and flowers in the summer. Thus, herbicide is commonly used to kill rye prior to planting spring crops. Oats, in contrast, grows rapidly in the autumn but is killed by frost during the winter. Thus, with oats, potentially less herbicide is needed to prepare the field for spring planting. When compared to fallow, oats was as effective as rye in increasing mycorrhizal colonization of sweet corn, density of mycorrhizal hyphae, and soil aggregate stability. An oats cover crop may thus be a viable alternative to rye. The combination of cover crops (rye and oats), however, was significantly better than single species of cover crops in terms of sweet corn mycorrhizal colonization, P uptake and yield of sweet corn.

Evaluation of six chickpea varieties for seed yield under autumn and spring sowing

The possibility of increasing seed yield in chickpeas was studied by changing sowing time from spring to autumn in an experiment conducted in central Greece over 4 years. Six chickpea varieties, two susceptible to Ascochyta blight and Sclerotinia diseases and four resistant, were evaluated in two sowing seasons (autumn and spring).Results showed that autumn sowing in comparison with spring influenced reproductive and growth periods of the varieties as follows: advanced initiation of flowering (April instead of May), increased flowering duration of the varieties from 7 to 13 days and advanced time for harvest, on average up to 4 days when an exceptionally rainy spring prevailed and up to 30 days when exceptionally dry. Due to the above changes induced by autumn sowing, varieties yielded on average from 23–188% (655–1015 kg/ha) more than if they were sown in spring. The largest per cent increase was observed during the year with the driest spring and the smallest during the year with the wettest spring. The two susceptible varieties ‘Thiva’ and ‘Gravia’ when infected by Ascochyta blight and Sclerotinia diseases in autumn sowing, had yields similar to the spring sowing. However, during the years without infection these two varieties yielded more in autumn sowing.