Melilotus Alba Desr Research Articles

Evaluation of White Sweet Clover (Melilotus alba Desr.) Genotypes in terms of Secondary Metabolite Contents.

Baklagiller familyasında yer alan taş yoncaları içermiş olduğu ikincil metabolitler ile hayvan besleme ve sağlığı açısından önem teşkil etmektedir. Diğer taraftan, kıraç ve fakir topraklarda kurulacak kısa süreli meraların kalitesinin artırılmasında kullanılan taş yoncalarının yem kalitesi yüksek olmakla birlikte, yonca ve üçgül türlerine göre şişme problemi daha azdır. Bu araştırma, Bilecik ili doğal florasından toplanan 17 adet aktaş yoncası genotipinin (Melilotus alba Desr.) toplam fenolik, toplam flavonoid, radikal kovucu aktivite (DPPH) ve kondanse tanen içeriklerinin belirlenmesi amacı ile yapılmıştır. Araştırma sonucuna göre, genotiplerin ortalama fenolik, flavonoid, DPPH ve kondanse tanen içerikleri sırasıyla 3.901 mg GA g-1, 17.962 mg QE g-1, %26.523 ve %0.611 olarak belirlenmiş olup, söz konusu bileşikler bakımından aktaş yoncası genotipleri arasında farklılıklar olmuştur. Ayrıca, çalışmada belirlenen bu bileşikler yem kalitesi ve hayvan sağlığı açısından çok önemli olup, sonuçlar ileride yapılacak çalışmalara ışık tutacak niteliktedir.

Doğal Floradan Toplanan Aktaş Yoncalarının (Melilotus alba Desr.) Bazı Kalite Özellikleri

Türkiye‘de kaliteli kaba yem açığı hayvansal üretimin en önemli sorunlarından biri iken, halen çok az sayıda yem bitkisinin tarımı yapılmaktadır. Diğer taraftan bitkisel gen kaynaklarının korunması, bugün dünyanın önemli bir sorunu haline gelmiştir. Nitekim biyolojik çeşitlilik, başta gıda olmak üzere insan yaşamının vazgeçilmez bir öğesi olup, 2030 yılına kadar bu kaynaklarının % 20‘sinin yok olacağı tahmin edilmektedir. Bu araştırma, Bilecik ili doğal florasından toplanan aktaş yoncalarının (Melilotus alba Desr.) bazı kalite özelliklerinin belirlenmesi amacıyla yürütülmüştür. Çalışmada bitkiler çiçeklenme döneminde toplanmış ve 17 adet genotip incelenmiştir. Genotiplerde belirlenen kalite özelliklerinden ham protein, ADF, NDF, NYD, K, P, Mg, Ca ve Ca/P değerleri sırasıyla %11,99-21,07; %27,70-40,53; %43,31-55,84; 93,44-147,02; %1,300-2,807; %0,187-0,310; %0,127-0,350; %0,490-1,417 ve %2,05-5,92 arasında değişmiştir. Çalışma sonucunda Bilecik ili doğal florasından toplanan aktaş yoncalarının kalite özellikleri bakımından iyi değere sahip olduğu ve buna göre, 17 farklı lokasyondan toplanan aktaş yoncalarının hayvan beslenmesinde kullanılabileceği ve geleceğe yönelik ıslah çalışmaları için önemli bir potansiyele sahip olduğu tespit edilmiştir.

Yarı Kurak Alanlarda Bulunan Melilotus officinalis (L.) Desr. ve Melilotus alba Desr. (Fabaceae) Taksonlarının Fitojeomorfolojik Özellikleri

Bu çalışma, Çankırı ili Yapraklı ilçesinde bulunan Büyükyayla mevkisinin doğal bitki örtüsü içinde yer alan Melilotus officinalis (L.) Desr. ve Melilotus alba Desr. taksonlarının morfolojik, ekolojik ve iklim özelliklerinin belirlenmesi amacıyla hazırlanmıştır. İç Anadolu bölgesinin kuzeyinde yer alan çalışma alanı P.H. Davis‘ in Grid sistemine göre A4 karesi içerisine girmektedir. Çalışma alanının iklimi Emberger Yöntemi kullanılarak belirlenmiştir. Çalışma alanının bitki ve toprak örneklemeleri 2014 yılı vejetasyon dönemi boyunca yapılmıştır. Melilotus officinalis (L.) Desr. taksonuna ait morfolojik karakterlerden, bitki boyu, korolla, meyve için yapılan ölçümler Davis (1965-1988)‘ in çalışmaları ile uyumluluk gösterirken, rasem için yapılan ölçümler arasında farklılıklar tespit edilmiştir. Çalışma sonucunda, Melilotus alba Desr. taksonuna ait morfolojik karakterlerden ise, rasem, çiçek, korolla ve meyve için yapılan ölçümler Davis (1965-1988)‘ in çalışmaları ile uyumluluk gösterirken, bitki boyu için yapılan ölçümler arasında farklılıklar tespit edilmiştir. Taksonların genel ekolojik özelliklerini belirlemek amacıyla 0-30 cm‘den alınan toprak örneklerinde yapılan analizler sonucunda tekstür, pH, CaCO3 ve HA değerleri taksonların bulunduğu alanlardaki topraklarda değişkenlik göstermiştir. Bu durum aynı cins bitkilerin yetişme ortamı isteklerinin farklı olduğunu göstermektedir.

Seed Fatty Acid Composition of Some Medicago L. and Melilotus L. (Fabaceae) Taxa From Turkey

Fatty acids composition of plant oil of Medicago disciformis DC., Medicago orbicularis (L.) Bart., Medicago intertexta (L.) Mill var. ciliaris (L.) Heyn., Medicago scutellata (L.) Mill., Melilotus alba Desr. and Melilotus officinalis (L.) Desr. were analyzed. The fatty acid composition of these six different taxa were determined by gas chromatography. The fatty acid composition of plants used to this study showed different saturated and unsaturated fatty acid concentrations. The main fatty acids found were linoleic acid (19.43-56.25%), linolenic acid (22.10-36.35%), oleic acid (18.56-31.21%), stearic acid (3.16-5.09%) and palmitic acid (11.93-23.37%); while other fatty acids were found in minor proportions. As a result, present study determined that all taxa had the highest total unsaturated fatty acid amounts (69.81-82.53%) and the lowest total saturated fatty acid amounts (17.47-30.19%). The higgest unsaturated fatty acid determinated to Melilotus officinalis (82.53%), the lowest in Medicago intertexta (69.81%). In the study of species, palmitic and stearic acid were found, the major saturated fatty acids. The other hand oleic, linoleic and linolenic acids in major unsaturated fatty acids. Fatty acid composition of studied plants oils could be used as a chemotaxonomical marker.

Effect of sweetclover cultivars and management practices on following weed infestations and wheat yield

There is a renewed interest, especially among organic growers, in using either white sweetclover (Melilotus alba Desr.) or yellow sweetclover [M. officinalis (L.) Lam.] as cover crops. Sweetclover cultivars and tillage practices have changed since these crops were widely used as cover crops in the first half of the 20th century. Experiments were initiated in 1999, 2000, and 2002 to compare the effect of high- and low-coumarin cultivars and crop termination methods on weed suppression, available soil N, moisture conservation and following crop yield. Weed suppression was usually more effective when sweetclover residues were left on the surface than when removed as hay. Sweetclover termination at 70% bloom was often more effective in suppressing weeds than termination at the bud stage. In the summer and fall after termination, surface residues of Yukon, a high-coumarin and drought-tolerant cultivar, reduced lamb’s-quarters (Chenopodium album L.) density by > 80% compared with the no sweetclover check and essentially eliminated flixweed [Descurainia Sophia (L). Webb]. In the following spring, Yukon reduced kochia [Kochia scoparia (L.) Schrad.] density by > 80% and wild oat (Avena fatua L.) biomass by > 30% compared with the no sweetclover check. There was no difference in available N for a following crop between treatments with surface residue and cultivated fallow. Available soil moisture was about 10 mm less after the highest yielding sweetclover cultivars than after cultivated fallow, but subsequent wheat yield was not reduced. Maximum wheat yields were obtained after Yukon and Arctic sweetclover were grown as cover crops. It may be possible for organic growers to manage weeds with sweetclover in a reduced tillage system that leaves most of the plant residues on the soil surface. Key words: Cover crop, weed suppression, allelopathy, nitrogen, soil moisture

ENOD40 Gene Expression and Cytokinin Responses in the Nonnodulating, Nonmycorrhizal (Nod−Myc−) Mutant, Masym3, of Melilotus alba Desr.

Several nonnodulating, nonmycorrhizal (Nod−Myc−) mutants of Melilotus alba Desr. (white sweetclover) have been described. However, the details of their responses to Sinorhizobium meliloti have not been fully elucidated. We investigated rhizobial entry and colonization using Confocal Scanning Laser Microscopy on the Masym1–5 mutants and isolated an early nodulin (ENOD40) gene from wild-type M. alba. We focused on Masym3, the least responsive of the mutants to S. meliloti and VA-fungi, to determine its response to cytokinin. Cytokinin appears to be a downstream signal in the nodule developmental pathway based not only on our previous observations whereby Nod−Myc− alfalfa roots treated with cytokinin accumulated several ENOD gene transcripts, but also on recent reports showing the importance of cytokinin receptors for nodulation. Here we show that applying 10−6 M 6-benzylaminopurine to uninoculated Masym3 roots elicited ENOD40 transcript accumulation. In addition, Masym3 root hairs inoculated with either wild-type S. meliloti or Nod− S. meliloti expressing the trans-zeatin synthase gene of Agrobacterium tumefaciens exhibited tip swelling, suggesting that cytokinin mediated this response. However, Masym3 root hair tips swelled following inoculation with Nod− S. meliloti or after mock-inoculation, a response resembling the phenotype of root hairs, after handling, of the Medicago truncatula mutant, dmi2. Mtdmi2 is Nod−Myc− due to a defect in a gene encoding a Nodule Receptor Kinase (NORK). Like Mtdmi2, the root hair swelling response appears in part to be mediated by touch because Masym3 root hairs not contacted by either bacteria or drops of water or buffer remain elongated and do not exhibit tip swelling.

A feeling for the micro-organism: structure on a small scale. Biofilms on plant roots

Biofilms are structured communities of bacterial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living surface; they have clinical, industrial and environmental impacts. Biofilms that are established by bacteria on plants are found on the surfaces of roots, leaves, seeds and internal vascular tissues where the microbes live in commensal, mutualistic or parasitic/pathogenic associations with their host. The study of the structure of plant-associated biofilms has been considerably helped by the development of techniques using fluorescent markers coupled with confocal scanning laser microscopy as well as scanning electron microscopy. We review several of these techniques as well as some of the research that has dealt with plant-associated biofilms. Our investigations focus on biofilm formation in the early stages of the Rhizobium–legume symbiosis, in which Gram-negative rhizobia provide fixed nitrogen to a host legume, and in return, the legume provides carbon-containing molecules. Because root colonization is an important early step in the establishment of the nitrogen-fixing symbiosis, we looked at Sinorhizobium meliloti attachment and biofilm establishment on the roots of its legume hosts, Medicago sativa L. and Melilotus alba Desr. We also examined biofilm formation by Rhizobium leguminosarum bv. viciae on the roots of Arabidopsis thaliana (L.) Heynh., a non-legume and non-host. Our ultimate goal is to characterize the rhizobial genes involved in aggregation and attachment to roots because several of these appear to be shared in biofilm formation and rhizobial entry of legume root cells.

Effects of a Nod-factor-overproducing strain of Sinorhizobium meliloti on the expression of the ENOD40 gene in Melilotus alba

We have initiated studies on the molecular biology and genetics of white sweetclover (Melilotus alba Desr.) and its responses to inoculation with the nitrogen-fixing symbiont Sinorhizobium meliloti. Early nodulin genes such as ENOD40 serve as markers for the transition from root to nodule development even before visible stages of nodule formation are evident. Using Northern blot analysis, we found that the ENOD40 gene was expressed within 6 h after inoculation with two different strains of S. meliloti, one of which overproduces symbiotic Nod factors. Inoculation with this strain resulted in an additional increase in ENOD40 gene expression over a typical wild-type S. meliloti strain. Moreover, the increase in mRNA brought about by the Nod-factor-overproducing strain 24 h after inoculation was correlated with lateral root formation by using whole-mount in situ hybridization to localize ENOD40 transcripts in lateral root meristems and by counting lateral root initiation sites. Cortical cell divisions were not detected. We also found that nodulation occurred more rapidly on white sweetclover in response to the Nod-factor-overproducing strain, but ultimately there was no difference in nodulation efficiency in terms of nodule number or the number of roots nodulated by the two strains. Also, the two strains could effectively co-colonize the host when inoculated together, although a few host cells were occupied by both strains.Key words: ENOD40, Nod factor, Melilotus, Sinorhizobium, symbiosis.

Inflorescence and flower development in wild-type and sid mutant Melilotus alba, white sweetclover

White sweetclover, Melilotus alba Desr. (Fabaceae), produces white, papilionoid flowers on a simple raceme. Individual floral apices originate in the axil of a bract. Each flower consists of five alternating whorls that, from outside to inside, consist of (i) five sepals, (ii) five petals, of which two fuse along their abaxial edges to form the keel, (iii) five antesepalous stamens, (iv) five antepetalous stamens with shorter filaments, and (v) a single carpel containing two to four ovules. The development of the wild-type sweetclover inflorescence and flowers is described in detail and compared with a mutant in which secondary inflorescences, instead of individual flowers, developed in axils of the bracts, especially at the base of the inflorescence. This white sweetclover mutant, designated sid for "secondary inflorescence development", might serve as a test of the ABC model of floral development, which was based on the model plants Antirrhinum and Arabidopsis.Key words: white sweetclover, inflorescence, flower, development, sid mutant.

Effect of post emergence herbicides on nutrient uptake by weeds and potato (Solanum tuberosum)

A field experiment was conducted during winter (rabo seasons of 1995 96 and 1996 97 at Hisar, to study the effect of post emergence herbicides on nutrient uptake by weeds and crop in potato (Solanum tuberosum L.). The field was dominated mainly by broad leaf weeds like Chenopodiurn album L. (50%), Melilotus alba Desr. (35%) and Coronopus didymus (15%). All the weed control treatments significantly reduced the dry weight of weeds and N, P and K uptake by weeds compared with weedy check. Among herbicides, minimum nutrient uptake by weeds and maximum by crop was recorded in the plots treated with linuron metribuzin (2 : 1) at 1.00 kglha, and it also recorded highest tuber yield which was at par with weed free check. The maximum nutrient uptake by weeds and minimum by crop with lowest tuber yield was found in weedy check, followed by glufosinate.

The Auxin Transport Inhibitor N-(1-Naphthyl)phthalamic Acid Elicits Pseudonodules on Nonnodulating Mutants of White Sweetclover.

The collection of symbiotic (sym) mutants of white sweetclover (Melilotus alba Desr.) provides a developmental sequence of mutants blocked early in infection or nodule organogenesis. Mutant phenotypes include non-nodulating mutants that exhibit root-hair deformations in response to Rhizobium meliloti, mutants that form ineffective nodules lacking infection threads, and mutants that form infection threads and ineffective nodules. Mutant alleles from both the sym-1 and the sym-3 loci exhibited a non-nodulating phenotype in response to R. meliloti, although one allele in the sym-1 locus formed ineffective nodules at a low frequency. Spot-inoculation experiments on a non-nodulating allele in the sym-3 locus indicated that this mutant lacked cortical cell divisions following inoculation with R. meliloti. The auxin transport inhibitor N-(1-naphthyl)phthalamic acid elicited development of pseudonodules at a high frequency on all of the sweetclover sym mutants, including the non-nodulating mutants, in which the early nodulin ENOD2 was expressed. This suggests that N-(1-naphthyl)phthalamic acid activates cortical cell divisions by circumventing a secondary signal transduction event that is lacking in the non-nodulating sweetclover mutants. The sym-3 locus and possibly the sym-1 locus appear to be essential to early host plant responses essential to nodule organogenesis.

Nodulin gene expression in effective root nodules of white sweetclover (Melilotus albaDesr.) and in ineffective nodules elicited by mutant strains ofRhizobium meliloti

Fifteen nodulins and several nodule-stimulated gene products were expressed in effective, nitrogen-fixing root nodules of white sweetclover (Melilotus alba Desr. cv. U389), as determined by two-dimensional gel electrophoresis of in vitro translation products. The number and gel position of eight leghaemoglobin (Lb) products, as well as a product tentatively identified as nodule-stimulated glutamine synthetase (GS), was similar to previous reports of alfalfa (Medicago sativa L. cv. Iroquois) nodulins. Three mutants of Rhizobium meliloti, including an exoH mutant, a lipopolysaccharide mutant, and a nifH mutant, elicited ineffective sweetclover nodules blocked at empty (bacteria-free), partially infected, or fully infected stages of nodule development, respectively. In these ineffective nodules, the nodulin Nma30 and nodule-stimulated NSTma42 were expressed early in development, while a group of four nodulins and two nodule-stimulated products were intermediate in order of expression. Lb, GS and the late nodulin Nmal2a were expressed later, following infection. The exoH mutant, Rm7154, appeared to be a leaky mutant, as a small percentage of the plants developed nitrogen-fixing nodules about 4 weeks after inoculation. The sequential expression of a large number of nodulins and nodule-stimulated products, as well as the availability of sweetclover nodulation mutants indicates that sweetclover is a useful diploid system for analysis of host genes essential to the Rhizobium/legume symbiosis.

Host Suitability of Forage Grasses and Legumes for Root‐Lesion Nematode Pratylenchus penetrans

Pratylenchus penetrans reduces the productivity of many forage crops in northern USA and eastern Canada. Our objective was to determine the host suitability of forage grasses and legumes for P. penetrans in greenhouse, growth chamber, and field environments. In the greenhouse and growth chamber environments, P. penetrans reproduced on all forage grasses (17) and legumes (12). Both the legumes and grasses varied (P < 0.05) for numbers of nematodes and eggs in the roots. The most suitable hosts included kura clover (Trifolium ambiguum M. Bieb.), alsike clover (Trifolium hybridum L.), white clover (Trifolium repens L.), oat (Avena sativa L.), and rye (Secale cereale L.). The least suitable hosts included pearl millet [Pennisetum glaucum (L.) R. Br.], tall fescue (Festuca arundinacea Schreber), perennial ryegrass (Lolium perenne L.), forage sorghum [Sorghum bicolor (L.) Moench], sudangrass (Sorghum sudanense Pers.), sudex (Sorghum sudanense ✕ S. bicolor), sweetclover (Melilotus alba Desr.), crownvetch (Coronilla varia L.), and MNGRN‐16alfalfa (Medicago sativa L.). Twelve legumes and 9 grasses were transplanted into a field infested with P. penetrans and one‐half the plants were treated with carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranol methylcarbamate). Pratylenchus penetrans reproduced on all entries. Numbers of nematodes per gram fresh root of entries in the greenhouse‐growth chamber and field tests were correlated for both the control (r = 0.60, P< 0.05) and carbofuran treatment (r = 0.48, P < 0.05). We concluded that many forage species are hosts for P. penetrans, but a few legumes and grasses are poor hosts and may be useful in forage rotations to reduce nematode populations.

Investigations of the host feeding preferences of Sitona weevils found commonly on white clover (Trifolium repens) in the UK

AbstractA series of laboratory and field studies were done to evaluate a range of leguminous plant species for their feeding potential by adult weevils of the genus Sitona Germar. (Coleoptera: Curculionidae). Three species of Sitona, S. lineatus L., S. flavescens Marsh. and S. hispidulus F. all of which are found commonly on white clover (Trifolium repens L.) in the UK were offered a range of 11 legume species, T. repens (white clover, cv. Olwen), T. pratense L. (red clover, cv. Marcom), T. fragiferum L. (strawberry clover, cv. Palestine), T. hybridum L. (hybrid clover, cv. Tetra), T. incarnatum L (crimson clover), T. dubium Sibth. (lesser yellow trefoil), Lotus corniculatus L. (birdsfoot‐trefoil, cv. Leo), L. uliginosus Schkuhr. (large birdsfoot‐trefoil), Melilotus alba Desr. (white melilot), Medicago sativa L. (lucerne, cv. Europe) and M. lupulina L. (black medick) in two laboratory experiments. The weevils were offered a choice of these legumes in one experiment whilst in the other they did not have a choice of food material. These legumes were also sown in the field and a number of measurements of damage, together with counts of Sitona spp., were made. In the laboratory S. lineatus and S. hispidulus favoured some of the legumes to a greater or lesser extent than white clover. S. flavescens was more restricted in its feeding than the other two weevil species. In the field study S. lineatus invaded the experimental area quickly and tended to favour Medicago spp. and Melilotus spp. Later in the year S. flavescens dominated the sitona fauna on the experiment, with the exception of aggregations of S. lineatus on M. sativa and M. alba. In a separate screen of 5 varieties of white clover (cvs Donna, Menna, Kersey, Olwen and Grasslands Huia), cv. Olwen appeared to be the most susceptible to sitona attack.

Two Sweetclover (Melilotus alba Desr.) Mutants Temperature Sensitive for Chlorophyll Expression.

The nonallelic sweetclover (Melilotus alba Desr.) mutants U371 (ch10/ch10 genotype) and U372 (ch11/ch11 genotype) are derived from the U389 (+/+ genotype) parental strain. Growth of the U389 strain at a temperature of 17 or 26[deg]C results in plants normally green in appearance. The U371 and U372 mutant plants grown at 26[deg]C are slightly to moderately chlorophyll (Chl) deficient and have decreased Chl b/a ratios. Growth of the mutants at 17[deg]C results in plants severely deficient in Chl a, with markedly reduced levels of carotenoids except for violaxanthin, and with negligible amounts of Chl b or apoproteins for the light-harvesting complex of photosystem II. If mutant plants grown at 17[deg]C are transferred to 26[deg]C, during the next 20 d the amount of Chl per fresh weight will increase 5-fold and both the Chl b/a ratio and the expression of the light-harvesting complex apoproteins will progressively increase. Studies of the U371 mutant during the temperature-induced greening demonstrate progressive changes in chloroplast ultra-structure and leaf carbon isotope fractionation that parallel the increases in Chl. Changes observed in the leaf carbon isotope fractionation in the mutant suggest that, in addition to the already known effects of various abiotic factors, structural and metabolic internal factors can also influence whether the limitation in CO2 fixation is at the level of diffusion or carboxylation. Such temperature-initiated progressive greening in these and similar mutants may make them useful tools to elucidate not only the biosynthesis and assembly of the photosynthetic apparatus, but also physiological phenomena such as the influence of light-driven energy production on the overall carbon isotope fractionation during photosynthesis.

Five Nodulation Mutants of White Sweetclover (Melilotus alba Desr.) Exhibit Distinct Phenotypes Blocked at Root Hair Curling, Infection Thread Development, and Nodule Organogenesis.

In an effort to obtain a developmental sequence of mutations in the Rhizobium-legume interaction within a single legume species, we have characterized the early events of nodule development in 10 nodulation mutants of sweetclover, Melilotus alba Desr. cv U389, representing five genetic loci. Both seed and root exudates from all of the sweetclover mutants induced expression of the nod genes of Rhizobium meliloti. Mutants in three loci were blocked in the early stages of root hair curling. Of these, a mutant in the sym-3 locus exhibited root hair deformations in response to inoculation with R. meliloti but produced no nodules or emerging nodule primordia, suggesting a blockage in the signal transduction events leading to nodule organogenesis. In contrast, mutants in both the sym-1 and sym-5 loci formed ineffective nodules in response to inoculation but differed slightly in the type of root hair response observed. None of these three early mutants formed infection threads. Infection threads were observed in mutant sym-2 as well as in ineffective nodules. Mutant sym-4 also formed infection threads but lacked nodules. The phenotypes observed for mutants from these five loci suggest that a secondary receptor or signal produced by the plant is required for nodule development.

Root size and shoot/root ratio as influenced by light environment of the shoot

Abstract The light environment of a plant shoot can affect its root size and the shoot/root biomass ratio. Photoperiodic influence on shoot/root ratios of first‐year biennial sweetclover (Melilotus alba Desr.) plants was related to phytochrome measurement of day length and its regulation of photosynthate partitioning to favor successful completion of the life cycle. Short photoperiods alternated with long, uninterrupted nights resulted in low‐growing shoots and rapidly enlarging taproots. The ratio of far‐red (FR) relative to red (R) light and its effect on shoot/root biomass ratios were studied in controlled environments, in different field population densities, and among plants growing in full sunlight but receiving different spectral distributions of upwardly reflected light over different colored soils, plant residues or artificially colored mulches. Altered spectral distribution of reflected light can act through photomorphogenic pigments within a plant and influence photosynthate partitioning and sh...

Growing Legumes with ‘Coastal’ Bermudagrass in the Lower Coastal Plain

Adding legumes to perennial pastures can increase forage quality and decrease costs of N fertilizer. This research was conducted to determine the productivity of seven legumes grown with ‘Coastal’ bermudagrass (Cynodon dactylon L.) fertilized at nine rates for 3 yr on a Lynchburg sand (fine-loamy, siliceous, thermic Aerie Paleaquults) in the lower Coastal Plain of Georgia. A randomized block design with split plots and six replications was chosen for the test. Forage species were whole plots and fertilizer treatments were subplots. The legumes grown without N were Oregon common Ladino clover (Trifolium repens L.); Louisiana common white clover (T. repens L.); ‘Dixie’ crimson clover (T. incarnatum L.); subterranean clover (T. subterraneum L.); annual white sweetclover (Melilotus alba Desr.); and big trefoil (‘Hairy’ and ‘Smooth’) (Lotus uliginosus Schkuhr.). The Coastal bermudagrass monoculture received the same nine fertilizer treatments plus 100 lb/acre of N on 6 May as a check. Except for N, fertilizers were applied each fall. Excellent legume stands were obtained and maintained with late-fall seedings. Forage yields were taken 6 May, 11 June, 21 July, and 22 Sept. Mixtures with Louisiana white, Dixie crimson, subterranean, or annual sweetclover yielded nearly half of their total production in the 6 May harvest. Only mixtures with sweetclover or Oregon Ladino clover produced more dry matter than Coastal bermudagrass alone with annual applications of 100 lb/acre of N. Oregon Ladino clover persisted as a weak perennial. Adding 25 lb N/acre to the fall application of 0-50-50 failed to increase average yields of the legumes but did increase yields of Coastal bermudagrass. Doubling the P and K application from 50 to 100 lb/acre increased the average clover-plus-bermudagrass forage yield by 920 lb/acre but had no effect on yields of Coastal bermudagrass growing alone. Properly fertilized Ladino clover produced 430 lb/acre more crude protein than bermudagrass with 100 lb N/acre.

Inheritance of Nonnodulating Mutants of Sweetclover

Legume mutants defective in nodule formation are useful for understanding interactions between host and bacterium. Nonallelic nodulation mutants have been relmrted within only a few legume species. Inheritance of nonnodulation in 10 sweetclover (Melilotus alba Desr.) mutants was determined from F1, F2, and F3 generations derived from crosses between each mutant and the nodulating accession U389. Nonnodulation in each mutant was conditioned by a single recessive gene. Complementation analysis was performed on F1 and F2 seedlings derived from diallel crosses among the mutants. Five of the mutants were nonallelic, indicating that at least five different genes are involved in nodule formation in M. alba. The following symbols are proposed for the genes controlling nonnodulation of these sweetclover mutants: sym‐1, sym‐2, sym‐3, sym‐4, and sym‐5.

Cross‐Pollination Technique for Spontaneously Self‐Pollinated Sweetclover

There is increased interest in using a dwarf, spontaneously self‐pollinated accession (U389) of annual, white‐flowered sweetclover (Melilotus alba Desr.) for studying N2 fixation and for characterizing the photosynthetic apparatus. Genetic analysis of this accession may therefore be required. In a study of the inheritance of 10 nonnodulating U389 mutants > 2000 crosses made in the late bud stage were unsuccessful probably because florets were mishandled during the crossing procedure. Development of an improved crossing technique resulted in production of hybrid seed from 20% of the emasculated and pollinated florets. This successful technique is described in detail for future use by researchers making crosses with spontaneously self‐pollinated sweetclovers similar to U389.