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Cover crop (CC) benefits and adoption in crop rotations may be limited by the short planting window after the cash crop. Interseeding or relay intercropping of CC is a technique that could overcome short planting windows constraints and allow CC establishment and growth. However, in Mediterranean regions this technique has been poorly implemented. Field experiments were established in Central Spain during two consecutive growing seasons to assess the performance of different species as interseeded crops into irrigated maize (Zea mays L.). The treatments included annual ryegrass (Lolium multiflorum L.) and eight legumes: burr medic (Medicago polymorpha L.), barrel medic (Medicago truncatula L.), yellow sweetclover (Melilotus officinalis L.), berseem clover (Trifolium alexandrinum L.), balansa clover (Trifolium michelanium L.), red clover (Trifolium pratense L.), Persian clover (Trifolium resupinatum L.), and common vetch (Vicia sativa L.). A bare soil was included as control treatment. After the maize harvest, the four species with the best performance were planted as autumn cover crops in adjacent plots. The ground cover was studied throughout the experimental period, and biomass and N content for each species were determined in the autumn and in the following spring prior to the cover crop termination. The soil inorganic N content was determined in spring. Barrel medic, yellow sweetclover, common vetch and annual ryegrass were the species with the best performance in terms of soil coverage during the summer. Red clover and Persian clover had good establishment in one out of two years. None of the interseeded species impaired maize grain yield or quality. Interseeded species achieved better soil coverage and increased the biomass accrued at autumn compared to cover crops sown in October. Therefore, interseeded species ensured longer ground coverage, increasing the potential for soil quality improvement or weed suppression. Moreover, the higher biomass achieved by interseeded species ensured the survival of yellow sweetclover, which was winter killed when planted in the autumn. Interseeded cover crops enhanced the potential of N leaching reduction compared to autumn cover crops. This experiment confirms the suitability of different species interseeded in summer into irrigated maize in Mediterranean regions, and highlights the extra benefits of this practice in annual rotations.

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 (Tt) and the base temperature (Tb) 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 Tt 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 Tt and a minimum photoperiod were reached, which were specific to each species.

Fifteen years ago subterranean clover (Trifolium subterraneum) and annual medics (Medicago spp.) dominated annual pasture legume sowings in southern Australia, while limited pasture legume options existed for cropping areas of subtropical Australia. Since then a number of sustainability and economic challenges to existing farming systems have emerged, exposing shortcomings in these species and the lack of legume biodiversity. Public breeding institutions have responded to these challenges by developing 58 new annual and short-lived perennial pasture legumes with adaptation to both existing and new farming systems. This has involved commercialisation of new species and overcoming deficiencies in traditional species. Traits incorporated in legumes of Mediterranean Basin origin for the Mediterranean, temperate and southern subtropical climates of Australia include deeper root systems, protection from false breaks (germination-inducing rainfall events followed by death from drought), a range of hardseed levels, acid-soil tolerant root nodule symbioses, tolerance to pests and diseases and provision of lower cost seed through ease of seed harvesting and processing. Ten new species, French serradella (Ornithopus sativus), biserrula (Biserrula pelecinus), sulla (Hedysarum coronarium), gland (Trifolium glanduliferum), arrowleaf (Trifolium vesiculosum), eastern star (Trifolium dasyurum) and crimson (Trifolium incarnatum) clovers and sphere (Medicago sphaerocarpos), button (Medicago orbicularis) and hybrid disc (Medicago tornata × Medicago littoralis) medics have been commercialised. Improved cultivars have also been developed of subterranean (T. subterraneum), balansa (Trifolium michelianum), rose (Trifolium hirtum), Persian (Trifolium resupinatum) and purple (Trifolium purpureum) clovers, burr (Medicago polymorpha), strand (M. littoralis), snail (Medicago scutellata) and barrel (Medicago truncatula) medics and yellow serradella (Ornithopus compressus). New tropical legumes for pasture phases in subtropical cropping areas include butterfly pea (Clitoria ternatea), burgundy bean (Macroptilium bracteatum) and perennial lablab (Lablab purpureus). Other species and cultivars of Mediterranean species are likely to be released soon. The contributions of genetic resources, rhizobiology, pasture ecology and agronomy, plant pathology, entomology, plant chemistry and animal science have been paramount to this success. A farmer survey in Western Australia has shown widespread adoption of the new pasture legumes, while adoption of new tropical legumes has also been high in cropping areas of the subtropics. This trend is likely to increase due to the increasing cost of inorganic nitrogen, the need to combat herbicide-resistant crop weeds and improved livestock prices. Mixtures of these legumes allows for more robust pastures buffered against variable seasons, soils, pests, diseases and management decisions. This paper discusses development of the new pasture legumes, their potential use and deficiencies in the current suite.

Field experiments were conducted to investigate the performance of temperate legume species in rice-based cropping systems in a warm-temperate environment in Nepal. Over the period 1994–1996, various legume species were grown during the winter season (October–May) in the Kathmandu valley (27° N, 1350 m asl) with the aim of evaluating their biomass production and N fixation. A wide range of legume species including food, feed and green manure crops proved to be very well adapted to the winter growing conditions in this environment. The cultivation of temperate legume crops therefore, constitutes an alternative to traditional cropping practices such as growing wheat or leaving the land fallow. The temperate species appeared to capitalise on generally favourable growing conditions such as long growing season, low pest and disease pressure, high radiant energy receipt and cool night temperatures. However, performance varied greatly between species and years. Total dry matter yields ranged from 2 to 20 t ha −1 obtained with lentil ( Lens culinaris Medic) and bitter lupin ( Lupinus mutabilis ), respectively. Highest seed yields were produced by fababean ( Vicia faba ) (5 t ha −1 ) and field pea ( Pisum sativum var. arvense ) (3 t ha −1 ) in the first season. Nitrogen yields and quantities of N fixed ranged from 18 to 481 kg ha −1 and from 0 to 463 kg ha −1 , respectively. Large amounts of N were fixed by species such as fababean, Persian clover ( Trifolium resupinatum ) and bitter lupin. Early sowing in autumn was shown to be beneficial for some crops such as fababean, vetch ( Vicia benghalensis ) and Persian clover. In these cases, it is, therefore, important to reduce the turn-around interval after rice. Further research is required to fully determine the potential of temperate legume species in these environments with particular emphasis given to the identification of the most adapted cultivars and to reduce the need for irrigation of these winter crops.

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.

A field study was initiated in July 1984 in the Karnal district of Haryana, India to examine the forage production, mineral composition, nutrient cycling and reclaiming effects of Karnal grass ( Leptochloa fusca (L) Kunth) grown in association with mesquite ( Prosopis juliflora (SW) DC) in an agroforestry system on an extremely alkaline soil (pH 10.4, exchangeable sodium percentage 90). Karnal grass inter-crop gave 47 t ha −1 green forage in 15 cuttings without any amendment in a growth-period of about 50 months, proving its potential as a primary colonizer of abandoned alkali lands. The inorganic chemical composition of the grass, including trace elements Fe, Mn, Zn and Cu, indicated that the grass may be valuable fodder under these adverse edaphic conditions. Removal of 453 kg ha −1 of N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu in the crop in a 2-year growth-period did not result in any site depletion in available nutrients. Growing of Karnal grass with mesquite for a period of 52 months reduced pH and EC and improved organic C, available N and water intake capacity of a barren alkali soil. Further, the soil was improved to the extent that some moderately salt-tolerant crops such as Trifolium resupinatum, T. alexandrinum and Melilotus denticulata have been grown successfully after ploughing-under of Karnal grass. This study suggested that the biological approach for utilization and improvement of abandoned alkali soils is feasible. Under certain specific situations where the amendments either are not available or are costly, this approach may, indeed, be the only economic method of utilization of these marginal land resources.