Polymorpha Var Research Articles

Sem Studies on Spermoderm of some Species of <i>Medicago</i> (Papilionoideae-Trifolieae)

Seeds of 9 species of Medicago have been investigated under light and scanning electron microscope to find out the systematic significance of spermoderm pattern. Under light microscope, the surface is smooth in all the species except M. monantha and M. orbicularis where it is tuberculate. Under scanning electron microscope, majority of species viz., M. laciniata , M. lupulina, M. minima, M. orbicularis. M. polymorpha var. vulgaris and M. × varia show tuberculate (papillose) pattern while M. edgeworthii, M. monantha and M. sativa show false reticulate, reticulate and rugulate patterns respectively. The nature of tubercules differs from species to species and thus spermoderm pattern can be used in the identification of plants at specific level.

Sequential infections by 32 isolates of

Context Studies of Phoma black stem and leaf spot disease (caused by Phoma medicaginis) in annual medics (Medicago spp.) normally involve a ‘once-only’ inoculation not reflecting multiple pathogen infection and phytoestrogen production cycles in the field. Phytoestrogen production by plants can result in lower ovulation rates in grazing animals. Aims We aimed to determine whether sequential infections by P. medicaginis increase production of phytoestrogens in annual medics, and to measure the genetic diversity of isolates. Methods In a greenhouse experiment, pathogenicity and virulence were investigated across 32 isolates of P. medicaginis following one, two or three rounds of inoculation of M. polymorpha var. brevispina. Production of the phytoestrogens coumestrol and 4′-O-methyl coumestrol was measured, and correlation with disease parameters assessed. DNA sequencing using ITS, β-tubulin, calmodulin and P. medicaginis-specific EFNI-1α was applied for phylogenetic analysis of isolates from Western Australia and elsewhere. Key results Across isolates, highest leaf disease incidence was 76%, petiole disease incidence 61%, leaf disease severity 52% and petiole disease severity 53%. Stem coumestrol content range was 45–1247 mg kg−1, and 4′-O-methyl coumestrol 0–344 mg kg−1. All measures were highest after three rounds of inoculation. Overall, there was a positive correlation of leaf disease incidence with coumestrol content (P < 0.05) and of both leaf and petiole disease incidence with 4′-O-methylcoumestrol content (P < 0.01, P < 0.05, respectively). Phylogenetic analysis revealed a high degree of genetic similarity among Western Australian isolates, generally grouping into a single separate cluster across the four markers, and genetically distinct from isolates sourced outside Australia. Conclusions Leaf disease incidence was the best discriminating disease parameter for coumestrol and 4′-O-methylcoumestrol content. Western Australian isolates of P. medicaginis were genetically similar and unique, possibly due to geographic separation. Implications The study emphasised the importance of sequential inoculations when screening annual Medicago genotypes towards developing cultivars with superior disease resistance and enhanced animal reproductive outcomes.

Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands.

Forty-two species of hydroids, excluding stylasterids, are reported in the present collection from the Northwestern Hawaiian Islands. Of these, four are anthoathecates and 38 are leptothecates. Among the latter, Sertularella affinicostata and Monotheca gibbosa are described as new species. The binomen Halopteris longibrachia is proposed as a new replacement name for Plumularia polymorpha var. sibogae Billard, 1913, an invalid junior primary homonym of P. sibogae Billard, 1911. Based largely on evidence from earlier molecular phylogenies, the genus Disertasia Neppi, 1917 is resurrected to accommodate species including Dynamena crisioides Lamouroux, 1824, Sertularia disticha Bosc, 1802, and Sia. moluccana Pictet, 1893. Sertularella robusta Coughtrey, 1876 is an invalid junior primary homonym of Sla. gayi var. robusta Allman, 1874a, and has been replaced here by the binomen Sla. quasiplana Trebilcock, 1928, originally described as Sla. robusta var. quasiplana Trebilcock, 1928. Clytia hummelincki (Leloup, 1935) is referred to the synonymy of its senior subjective synonym, C. brevithecata (Thornely, 1900). Following Reversal of Precedence provisions in the International Code of Zoological Nomenclature to preserve prevailing usage of binomena, the familiar names Sia. disticha Bosc, 1802 (also known as Dynamena disticha) and Lytocarpia phyteuma (Stechow, 1919b) are designated nomena protecta and assigned precedence over their virtually unknown senior synonyms Hydra quinternana Bosc, 1797 and Aglaophenia clavicula Whitelegge, 1899, respectively, names now reduced to the status of nomena oblita. Twenty species are reported for the first time from Hawaii [Eudendrium merulum Watson, 1985, Phialellidae (undetermined), Hebella sp., Hebellopsis scandens (Bale, 1888), H. sibogae Billard, 1942, Clytia brevithecata, C. linearis (Thornely, 1900), C. cf. noliformis (McCrady, 1859), Halecium sp., Sla. affinicostata, Sla. angulosa Bale, 1894, Pasya heterodonta (Jarvis, 1922), Tridentata orthogonalis (Gibbons Ryland, 1989), Pycnotheca producta (Bale, 1881), Monotheca gibbosa, H. longibrachia, A. postdentata Billard, 1913, A. suensonii Jderholm, 1896, A. whiteleggei Bale, 1888, and L. flexuosa (Lamouroux, 1816)]. Sertularia orthogonalis, reported for only the third time worldwide, is assigned to the genus Tridentata Stechow, 1920. Hydroids of the NOWRAMP 2002 collection consisted largely of presumptive widespread species, with over 75% of them having been reported elsewhere in the tropical Indo-west Pacific region.

Phoma medicaginis Isolate Differences Determine Disease Severity and Phytoestrogen Production in Annual Medicago spp.

Phoma black stem and leaf spot disease of annual Medicago spp., caused by Phoma medicaginis, not only can devastate forage and seed yield but can reduce herbage quality by inducing production of phytoestrogens (particularly coumestrol and 4'-O-methylcoumestrol), which can also reduce the ovulation rates of animals grazing infected forage. We determined the consequent phytoestrogen levels on three different annual Medicago species/cultivars (Medicago truncatula cultivar Cyprus, Medicago polymorpha var. brevispina cultivar Serena, and Medicago murex cultivar Zodiac) after inoculation with 35 isolates of P. medicaginis. Across the isolate × cultivar combinations, leaf disease incidence, petiole/stem disease incidence, leaf disease severity, petiole disease severity, and leaf yellowing severity ranged up to 100, 89.4, 100, 58.1, and 61.2%, respectively. Cultivars Cyprus and Serena were the most susceptible and cultivar Zodiac was the most resistant to P. medicaginis. Isolates WAC3653, WAC3658, and WAC4252 produced the most severe disease. Levels of phytoestrogens in stems ranged from 25 to 1,995 mg/kg for coumestrol and from 0 to 418 mg/kg for 4'-O-methylcoumestrol. There was a significant positive relationship of disease incidence and severity parameters with both coumestrol and 4'-O-methylcoumestrol contents, as noted across individual cultivars and across the three cultivars overall, where r = 0.39 and 0.37 for coumestrol and 4'-O-methylcoumestrol, respectively (P < 0.05). Although cultivar Serena was most susceptible to P. medicaginis and produced the highest levels of phytoestrogens in the presence of P. medicaginis, cultivar Zodiac contained the highest levels of phytoestrogens in comparison with other cultivars in the absence of P. medicaginis. There was a 15-fold increase in coumestrol in cultivar Serena but only a 7-fold increase in cultivar Zodiac from infection of P. medicaginis. The study highlights that the intrinsic ability of a particular cultivar to produce phytoestrogens in the absence of the pathogen, and its comparative ability to produce phytoestrogens in the presence of the P. medicaginis, are both important and highly relevant to developing new annual Medicago spp. cultivars that offer improved disease resistance and better animal reproductive outcomes.

Ancestral polymorphisms shape the adaptive radiation of Metrosideros across the Hawaiian Islands

Some of the most spectacular adaptive radiations begin with founder populations on remote islands. How genetically limited founder populations give rise to the striking phenotypic and ecological diversity characteristic of adaptive radiations is a paradox of evolutionary biology. We conducted an evolutionary genomics analysis of genus Metrosideros, a landscape-dominant, incipient adaptive radiation of woody plants that spans a striking range of phenotypes and environments across the Hawaiian Islands. Using nanopore-sequencing, we created a chromosome-level genome assembly for Metrosideros polymorpha var. incana and analyzed whole-genome sequences of 131 individuals from 11 taxa sampled across the islands. Demographic modeling and population genomics analyses suggested that Hawaiian Metrosideros originated from a single colonization event and subsequently spread across the archipelago following the formation of new islands. The evolutionary history of Hawaiian Metrosideros shows evidence of extensive reticulation associated with significant sharing of ancestral variation between taxa and secondarily with admixture. Taking advantage of the highly contiguous genome assembly, we investigated the genomic architecture underlying the adaptive radiation and discovered that divergent selection drove the formation of differentiation outliers in paired taxa representing early stages of speciation/divergence. Analysis of the evolutionary origins of the outlier single nucleotide polymorphisms (SNPs) showed enrichment for ancestral variations under divergent selection. Our findings suggest that Hawaiian Metrosideros possesses an unexpectedly rich pool of ancestral genetic variation, and the reassortment of these variations has fueled the island adaptive radiation.

Divergent Selection and Primary Gene Flow Shape Incipient Speciation of a Riparian Tree on Hawaii Island

A long-standing goal of evolutionary biology is to understand the mechanisms underlying the formation of species. Of particular interest is whether or not speciation can occur in the presence of gene flow and without a period of physical isolation. Here, we investigated this process within Hawaiian Metrosideros, a hypervariable and highly dispersible woody species complex that dominates the Hawaiian Islands in continuous stands. Specifically, we investigated the origin of Metrosideros polymorpha var. newellii (newellii), a riparian ecotype endemic to Hawaii Island that is purportedly derived from the archipelago-wide M. polymorpha var. glaberrima (glaberrima). Disruptive selection across a sharp forest-riparian ecotone contributes to the isolation of these varieties and is a likely driver of newellii’s origin. We examined genome-wide variation of 42 trees from Hawaii Island and older islands. Results revealed a split between glaberrima and newellii within the past 0.3–1.2 My. Admixture was extensive between lineages within Hawaii Island and between islands, but introgression from populations on older islands (i.e., secondary gene flow) did not appear to contribute to the emergence of newellii. In contrast, recurrent gene flow (i.e., primary gene flow) between glaberrima and newellii contributed to the formation of genomic islands of elevated absolute and relative divergence. These regions were enriched for genes with regulatory functions as well as for signals of positive selection, especially in newellii, consistent with divergent selection underlying their formation. In sum, our results support riparian newellii as a rare case of incipient ecological speciation with primary gene flow in trees.

Varieties of the highly dispersible and hypervariable tree, Metrosideros polymorpha, differ in response to mechanical stress and light across a sharp ecotone.

The drivers of isolation between sympatric populations of long-lived and highly dispersible conspecific plants are not well understood. In the Hawaiian Islands, the landscape-dominant tree, Metrosideros polymorpha, displays extraordinary phenotypic differences among sympatric varieties despite high dispersibility of its pollen and seeds, thereby presenting a unique opportunity to investigate how disruptive selection alone can maintain incipient forms. Stenophyllous M. polymorpha var. newellii is a recently evolved tree endemic to the waterways of eastern Hawai'i Island that shows striking neutral genetic differentiation from its ancestor, wet-forest M. polymorpha var. glaberrima, despite sympatry of these forms. We looked for evidence for, and drivers of, differential local adaptation of these varieties across the range of M. polymorpha var. newellii. For paired populations of these varieties, we compared seedling performance under contrasting light conditions and a strong water current characteristic of the riparian zone. We also conducted a reciprocal transplant experiment and contrasted adult leaf anatomy. Results suggest that the riparian zone is harsh and that selection involving the mechanical stress of rushing water, and secondarily, light, led to significant reciprocal immigrant inviability in adjacent forest and riparian environments. The strongest adaptive divergence between varieties was seen in leaves and seedlings from the site with the sharpest ecotone, coincident with the strongest genetic isolation of M. polymorpha var. newellii observed previously. These findings suggest that disruptive selection across a sharp ecotone contributes to the maintenance of an incipient riparian ecotype from within a continuous population of a long-lived and highly dispersible tree species.

Chemical composition of the seeds of some Medicago species

phytochemical properties of some legumes widely [9–12]. The objective of the present study was to determine the tannin, protein contents, and fatty acid composition of the seeds of Medicago L. species (M. disciformis DC., M. polymorpha L., M. intertexta (L.) Mill., M. scutellata (L.) Mill., M. truncatula Gaertn. and M. orbicularis var. marginata (L.) Bart.). The results of the fatty acid analysis are shown in Table 1, and total protein and tannin contents in Table 2. The total protein amounts of the feed crops studied were found to be between 30.50–47.17% in Medicago orbicularis var. marginata and M. truncatula. These were 34.87, 34.93, 36.20, and 38.30% in M. intertexta, M. scutellata, M. disciformis, and M. polymorpha, respectively. The protein levels were determined in fruit, leaf, and steam of Medicago noeana, M. orbicularis, M. polymorpha var. vulgaris, M. rigidula var. submitis, and M. rigidula var. rigidula [7]. According to them, the protein levels studied were found to be between 20% and 30%. The protein levels of fruits were found to be higher than those in leaf and steam. On the other hand, the protein contents of fruit of M. noeana, M. orbicularis, and M. polymorpha var.vulgaris were found to be higher than in fruits of other species. The tannin amounts of feed crops studied were found to be between 0.27–1.23% in M. orbicularis var. marginata and M. scutellata. The others comprise 0.30% (M. intertexta) and 0.70% (M. disciformis, M. polymorpha and M. truncatula), respectively. It was reported that condensed tannin may act as anthelmintics against parasitic nematodes or indirectly by improving nitrogen supply [13–15]. The main components in the seed oils of Medicago species were palmitic, oleic, linoleic, and linolenic acids. The other fatty acids of the legume seed oils (arachidic and lignoceric acid) in the studied species were shown to be lower than 1% except for M. truncatula (Table 1). This is similar to those reported [12]. On the other hand, behenic acid was at the highest level in M. disciformis (1.11%). Some researches have indicated that oils with high levels of long-chain SFA such as behenic acid may be difficult for digesting enzymes to digest in humans and animals [16]. The results of the present study, as far as unsaturated fatty acid content is concerned, are supported by previous leguminous studies [12, 17, 18]. All these studies showed that the saturated, and particularly unsaturated, fatty acid contents of Fabaceae seed oils are closely allied to each other and that the main components in the oils are linoleic-oleic type fatty acids. Seed Samples. Matured seeds of these species were collected from various locations in Adana (Turkey) between June and August 2009.

Volatile Composition of Trifolium and Medicago Species

The volatile compounds of Trifolium (Leguminosae) echinatum L., Trifolium stellatum var. stellatum L., Trifolium nigrescens subs. petrisavi (Celm) Holmboe, Medicago polymorpha var. vulgaris L., Medicago arabica (L.) Huds. and Medicago minima var. minima (L.) Grufbg. were obtained by hydrodistillation in a Clevenger-type apparatus, and then analyzed by gas chromatography-mass spectrometry (GC-MS) methods. In total, seventy-one constituents (terpenoids, alcohols, ketones, aldehydes, esters, hydrocarbons, fatty acids and benzene compounds) were identified from Trifolium oils and Medicago oils. According to the chemical class distribution of the oils of Trifolium and Medicago species, the fatty acids (29.7 – 63.4 % and 61.9 – 83.7 %, respectively) are the most abundant class of volatile compounds of three Trifolium and Medicago species. The present work is the first report on these plants oil composition.

REHABILITATION OF DEGRADED RANGELAND IN NORTHERN IRAQ

This study was conducted at Mahalabia region in Ninevah province in Northern Iraq 45 km south west of Mosul city for the three successive seasons 99/2000, 2000/2001 and 2001/2002. The amount of the rainfall is less than 300 mm. This study included two field experiments. First, conducted on rangeland shallow highly gypsum soil (24% gypsum). The two sites were represented the rangeland in the cereal wheat belt area. In the first site, three treatments were established, first treatment was control represents (natural vegetation) and the two others were cultivated with vetch (Vicia sativa L. Var. IPA 2001) with and without triple superphosphate fertilizer 160 kg/ha. The second experiment was conducted on plate an shallow clay soil (52% clay). Also, three treatments were set up. First, was control represents (natural vegetation) and the two others were cultivated with annual medics (Medicago polymorpha Var. circle valley) with and without triple superphosphate fertilizer 160 kg/ha. The results revealed, that add phosphate reduced the phosphorus deficiency in the soil and lead to increase dry matter production for vetch and annual medics. Also, there was increase in the pod and seed yields, weight of 100 pods and 1000 seed of annual medics. On the contrary, phosphorus had no effect on the number of seeds/pod. There were significant differences in dry matter production between treatment cultivated by vetch and annual medics with and without phosphorus fertilizer in comparison with control treatment. Successful rehabilitation of degraded rangeland lead to increase the stability of animal wealth in the area and stop animal moving from place to another looking for natural vegetation for their feeding.

Association of Fusarium species, with potential for mycotoxicosis, on pods of annual Medicago in Western Australia

A study was made on the incidence of Fusarium spp. associated with pods of annual Medicago species, in particular M. polymorpha var. brevispina, in Western Australia, including sites where either feed refusal or reduced feed intake by sheep had previously been reported. From a first series of 7 sites where M. polymorpha var. brevispina in particular, but also M. truncatula, were sampled, there was an extremely high incidence of F. acuminatum (83%) on pods at the Cunderdin site where feed refusal by sheep had been previously reported. There were high incidences of F. avenaceum on pods at Katanning (48–65%), but much lower incidences at Shackleton (7%), Merredin (5%), Kellerberrin (3%), and Cunderdin (1%). There was a high incidence of F. equiseti isolated from pods at Cunderdin (30%), but much lower incidences at Katanning (4–6%) and Shackleton (2%). F. chlamydosporum and F. graminearum were only isolated from pods at Cunderdin (14% and 9%, respectively). There were low incidences of F. oxysporum on pods at Katanning (2–4%) and Cunderdin (2%). In a second series of 15 randomly picked additional sites where only M. polymorpha var. brevispina pods were sampled, F. acuminatum was found at all 15 sites, with incidences ranging from 26 to 80% of pods carrying this fungus. F. avenaceum incidences were much lower (0–10%), but it was still recovered from 11 of the 15 sites. The incidences of other Fusarium spp. were generally low (0–6%, except for one case of 20%), and these were only isolated from 7 of the 15 sites. Our study is the first published report of Fusarium species associated with annual Medicago pods in Western Australia. F. acuminatum, F. avenaceum, F. equiseti, F. chlamydosporum, and F. graminearum have all previously been reported elsewhere to be toxigenic and one or more of these species may be associated with the sheep feed refusal and/or reduced feed intake situations observed in Western Australia.

Sources of Resistance to Anthracnose in the Annual Medicago Core Collection.

The annual genus Medicago core collection, consisting of 201 accessions, represents the genetic diversity inherent in 3,159 accessions from 36 annual Medicago species. This germ plasm was evaluated for resistance to anthracnose caused by Colletotrichum trifolii. Anthracnose is a major disease in perennial alfalfa (Medicago sativa L.) grown in North America and disease control is based principally on the use of resistant varieties. Evaluation of the core collection was conducted using standardized environmental conditions in growth chambers, and included the M. sativa standard reference cvs. Arc (resistant) and Saranac (susceptible). The degree of resistance found among accessions within species was highly variable; however, most annual species and accessions were susceptible. Only 14 accessions from seven species exhibited resistance greater than 40% seedling survival. These included accessions of M. murex, M. muricoleptis, M. polymorpha var. brevispina, M. polymorpha var. polymorpha, M. radiata, M. soleirolii, M. truncatula, and M. turbinata. Of the 12 accessions of M. polymorpha var. polymorpha, 4 exhibited more than 50% resistance, but 3 accessions were 100% susceptible. Most of the M. truncatula and M. turbinata accessions exhibited significantly more resistance than accessions of other species. Plant introduction (PI) accession number PI 495401 of M. muricoleptis exhibited 90.3% resistance. Accessions of M. scutellata were uniformly susceptible. Histological examinations of 14 of the most anthracnose-resistant accessions revealed that C. trifolii spores germinated and produced typical appressoria, but failed to penetrate and produce the primary and secondary hyphae characteristic of susceptible interactions. Resistant reactions were similar to those found in incompatible interactions with C. trifolii and alfalfa, which have been associated with specific genes leading to the production of isoflavonoid phytoalexins. The large genetic variability in annual Medicago spp. offers potential for locating and utilizing disease resistance genes through breeding or genetic engineering that will enhance the utilization of Medicago spp. as a forage crop.

Plant Phenology in a Cloud Forest on the Island of Maui, Hawaii1

ABSTRACTWe recorded the times of flowering, fruiting, and leafing for ten native canopy and subcanopy trees and shrubs (monthly from December 1994 through December 1997) in a montane cloud forest with relatively aseasonal rainfall on the island of Maui, Hawaii. These species represented the great majority of individual woody plants at the site. Flowers and fruits were available in the community year–round; however, all species exhibited annual patterns of flowering, and four species showed annual patterns of fruiting while the rest fruited in supra–annual patterns. Many species had protracted flowering or fruiting peaks, and some bore small numbers of flowers or fruit year‐round. Most species flowered in a monthly peak mainly between May and August, corresponding to the period of greatest solar irradiance and marginally higher temperatures. Fruit ripening followed at varying intervals. In contrast, the heaviest flowering occurred between November and March, resulting from bloom of the dominant tree, Metrosideros polymorpha. At the highest elevations, Metrosideros flowering was heaviest during September, but peak flowering of lower elevation trees occurred in late fall and winter. Two forms of this species differed in their temporal and spatial patterns of flowering. For M. polymorpha var. polymorpha and var. incana, bloom peaked annually between November and January; however, for M. polymorpha var. glaberrima, flowering peaked from April through July, with an earlier secondary peak in January.

Plant Phenology in a Cloud Forest on the Island of Maui, Hawaii1

We recorded the times of flowering, fruiting, and leafing for ten native canopy and subcanopy trees and shrubs (monthly from December 1994 through December 1997) in a montane cloud forest with relatively aseasonal rainfall on the island of Maui, Hawaii. These species represented the great majority of individual woody plants at the site. Flowers and fruits were available in the community year-round; however, all species exhibited annual patterns of flowering, and four species showed annual patterns of fruiting while the rest fruited in supra-annual patterns. Many species had protracted flowering or fruiting peaks, and some bore small numbers of flowers or fruit year-round. Most species flowered in a monthly peak mainly between May and August, corresponding to the period of greatest solar irradiance and marginally higher temperatures. Fruit ripening followed at varying intervals. In contrast, the heaviest flowering occurred between November and March, resulting from bloom of the dominant tree, Metrosideros polymorpha. At the highest elevations, Metrosideros flowering was heaviest during September, but peak flowering of lower elevation trees occurred in late fall and winter. Two forms of this species differed in their temporal and spatial patterns of flowering. For M. polymorpha var. polymorpha and var. incana, bloom peaked annually between November and January; however, for M. polymorpha var. glaberrima, flowering peaked from April through July, with an earlier secondary peak in January.

Ent-kaurene diterpenes from Gochnatia polymorpha var. polymorpha

Two diterpenes were isolated from the aerial parts of Gochnatia polymorpha var. polymorpha. Their structures were established as ent-3 β,19-diacetoxy-12 β,15 α-dihydroxy-kaur-16-ene and ent-17,19-diacetoxy-3 β,16 β- dihydroxykaurane, respectively. In addition, the aerial parts afforded cycloart-25-ene-3β,22α-diol and the flavoids genkwanin and desmethoxycentaureidin while the roots furnished taraxerol and the eudesmanolide santamarin.

The Effects of Cutting at Different Phenological Stages to Shoot and Root Development and Forage Yield of Annual Medics

This research, was conducted in the experimental fiels of Agronomy Department, Faculty of Agriculture, Ankara University, Turkey in 1989 and 1992 and in the greenhouse of Plant Science Department, Nova Scotia Agricultural College, Canada in 1991. The experiment was arranged in a split-plot design with four replications. Three annual medic species (Medicago polymorpha L. var. brevispina (Benth.) Heyn, Medicago scutellata (L.) Mill. and Medicago ciliaris (L.) Willd.) were the main plot units and cutting stages (a) beginning of flowering, b) %50 flowering, and c) end of flowering) were the sub-plot units. The highest stem development, root development and forage yields were taken from M. scutellata, however, M. polymorpha var. brevispina had the lowest values in both field and greenhouse experiments. The effects of cutting at different phenological stages and stem and root development and forage yields of annual medics were numerically higher in the greenhouse experiments than the field experiments. According to the progressive cutting stages, stem and root development and forage yields of annual medics were increased in the greenhouse experiment. Nodulation was occured in the field experiments, indicating the presence of native rhizobia. In the second greenhouse trial, seeds were inoculated commercial strain of Rhizobium meliloti for nodulation. But, only the nodules of M. scutellata were active for fixing nitrogen which was found by acetylene reduction assay.

The Morphology and Yield of Barley (Hordeum vulgare L.) and Forage Legumes in Intercrops

Seven forage Iegume species. Trİfolİum pratense L.. . T. resupinatum L.. Vicia villosa Roth.. Medİcago satİva L. cv. Nitro. M. scutellata (L.) Mill.. M. cilliaris (L.) and M. polymorpha (L.) var brevİspİna (Benth.) Heyn were intercropped with Hordeum vulgare L.. seeded at two rates in Nova Scotia-Canada (200 seeds/m^2 and 400 seeds/m^2) and the first harvest was at the silage and grain stages of barley. The Iegume main stem Iengths were Ionger at the Iower barley seeding rate and at the grain harvest in 1992. Vicia villosa consistently had Ionger stems than other Iegumes. V. villosa yielded more total dry matter and protein than other Iegumes except Trifolium pratense and Medicago satİva in 1991 and T. pratense at the silage harvest in 1992. As expected. in 1991. the Iower barley seeding rateresulted in Iower barley yields and higher totallegume yields but this trend was not significant. in 1992. Total dry matter and protein yields were also higher under grain than under silage harvesting in 1991 , but not in 1992.

Relative resistance, associated yield losses and phyto-oestrogen production from fungal foliar diseases in new and old annual Medicago cultivars

The relative resistance, associated herbage and seed yield losses and phyto-oestrogen production from fungal foliar diseases in two new annual Medicago cultivars, viz. M. sphaerocarpos cv. Orion and M. truncatula cv. Caliph, were compared with those of four old cultivars, viz. M. murex cv. Zodiac, M. polymorpha var. brevispina cw. Santiago and Circle Valley, and M. truncatula cv. Cyprus. Orion was much more resistant to Phoma stem disease than Circle Valley and Santiago, but was more susceptible than Zodiac. However, Orion was the most susceptible cultivar to Phoma leaf disease. Orion and Caliph were susceptible to Leptosphaerulina stem disease, resembling Santiago, but much more susceptible than Circle Valley and Zodiac. Caliph was comparable with Cyprus with moderate susceptibility to both Phoma and Leptosphaerulina on stems. Both Caliph and Cyprus were resistant to Pseudopeziza. In mid-October and early November, foliar diseases reduced overall herbage yield of the six varieties by 16.2 and 20.3% respectively, compared with the fungicide-treated plots of the same cultivars. Foliar diseases reduced seed yield by 37.3%, and mean seed weight by 13- 7% compared with fungicide treated plots. Foliar disease in the disease block increased the content of the phyto-oestrogen coumestrol in stems from 230 to 500 ppm and in pods from 30 to 130 ppm, compared with the fungicide block. There was a positive correlation between the severity of Phoma on stems and leaves and the level of coumestrol in stems and pods. Orion produced large amounts of coumestrol in stems and pods in response to foliar diseases (e.g. 470 ppm in stems) but less than Zodiac. Caliph also produced large amounts of coumestrol in stems and pods in response to foliar diseases (e.g. 230 ppm in stems), and was similar to Cyprus but had less coumestrol than all other cultivars tested (stems) or Zodiac, Circle Valley and Santiago (pods). Orion carried the highest level of P. medicaginis seed contamination (28%), followed by Santiago (15%), Cyprus (11%), Circle Valley (l0%), Zodiac (10%) and Caliph (6%).

Effective barley grass (Hordeum spp.) control in annual medics with 2,2-DPA herbicide

The ability of 2,2-dichloropropionic acid (2,2-DPA) to control annual grasses was examined in a 4-year-old medic (Medicago polymorpha var. brevispina cv. Circle Valley) pasture. Six rates of 2,2-DPA with and without spray adjuvants (1% spray oil + 0.25% wetting agent) were used: 0.37, 0.56, 0.74, 1.11, 1.48, 2.22 kg a.i./ha. The pasture was sprayed in July at the 4-true-leaf stage of the medic, after identifying and counting grasses and medics. Plants were counted again after spraying and grass seed heads were counted in spring. At the end of the season, medic seed yields were obtained. Nine annual pasture legumes were later evaluated for their tolerance to 2.22 kg 2,2-DPA/ha at 3 growth stages [post plant, pre-emergence (PPPE); 3-5-true-leaf stage; flowering] under weed-free conditions. A rate of 1.11 kg 2,2-DPAJha was found to reduce barley grass density by 85%. Efficacy was improved, however, with higher rates and/or the addition of spray adjuvants. Because of low silvergrass (Vulpia spp.) and ryegrass (Lolium rigidurn) plant numbers, it was not possible to assess whether 2,2-DPA controlled these species effectively. There was no effect of herbicide on medic seed yields, seed weight, seed number per pod, or seed germination. Medic seed yields were well correlated with plant density of medic but not with herbicide rates. There was a wide variation in biomass production of the 9 pasture legumes in the evaluation of tolerance, when assessed by visual rating and seed yield, with significant biomass and yield reductions at all timings of application of 2,2-DPA. Subterranean clover (Trifoliurn subterraneum L.) was the most severely affected. Generally, medic species tolerated 2,2-DPA well. Serena was the most susceptible medic cultivar at any treatment time, with seed yield reductions at the first 2 times of application. The results suggest that 2,2-DPA could be used safely on annual medics for the control of barley grass, and possibly other annual grasses.

Residual value of superphosphate and queensland rock phosphate measured using yields of serradella, burr medic and subterranean clover grown in rotation with wheat and bicarbonate‐extractable soil phosphorus

Abstract The residual value of ordinary (single) superphosphate (SP) and Queensland (Duchess) apatite rock phosphate was measured in a pot experiment using yields of three legume species (serradella, Ornithopus compressus; medic, Medicago polymorpha var. brevispina; clover, Trifolium subterraneum) fertilized with mineral nitrogen (N) grown in rotation with wheat (Triticum aestivum). The plants were grown in a glasshouse in a sandy soil (pH in CaCl2 ‐ 5.8) for 30 to 34 days. There were four crops: legume, wheat, legume, and wheat. The phosphate (P) requirement of the plant species was determined from the amount of P required to produce 90% of the maximum yield. Soil samples were taken before sowing each crop to measure bicarbonate‐extractable soil P (soil test P) which was related to the yields of that crop. Relative to freshly‐applied (FSP), the residual value of SP declined by about 60% between the first and second crop, and by a further 25% by the fourth crop. For crop 3, the residual value of SP varied...