Annual Medicago species in Morocco. I. Species and their abundance

1992 ◽  
Vol 43 (3) ◽  
pp. 739 ◽  
Author(s):  
M Bounejmate ◽  
PE Beale ◽  
AD Robson
Keyword(s):  
Seed Yield ◽  
Genetic Erosion ◽  
Soil Surface ◽  
Annual Medics ◽  
Annual Medicago ◽  
Medicago Species ◽  
Collection Sites

An ecogeographic survey of the distribution of annual medics in Morocco was conducted in 1988 by sampling 161 sites within six agricultural zones. At each site all medic pods lying on the soil surface were collected from five quadrats placed at random. Of the 18 medic species reported to occur in Morocco, only 11 were recorded in 1988. M. polymorpha and M. truncatula were the most frequent. Thirty-five sites had no medics in quadrats and 15 sites had no medics in the near vicinity. The average seed yield for all collection sites was 12.6 kg ha-1. Nearly 60% of the sites yielded less than 20 kg ha-1. More than 50 kg seed ha-1 was recorded at less than 10% sites. Maximum seed yield at any site was only of 169 kg ha-1. Results suggest that genetic erosion is occurring but occasional sites can be found where medics are abundant.

Effect of rotation and cultivation systems on establishment and persistence of annual medics

1989 ◽  
Vol 29 (2) ◽  
pp. 183 ◽  
Author(s):  
EJ Crawford ◽  
BG Nankivell
Keyword(s):  
Lower Proportion ◽  
The Other ◽  
Annual Plant ◽  
Plant Populations ◽  
The Third ◽  
Permanent Pasture ◽  
Seed Reserves ◽  
Annual Medics ◽  
Annual Medicago ◽  
Medicago Species

The persistence and annual and seasonal regeneration of 3 annual Medicago species, M. rugosa cv. Paragosa, M. scutellata cv. Robinson and M. truncatula cvv. Cyprus and Jemalong, were compared between 1978 and 1985 over 3 rotation systems, permanent pasture (R1); pasture, barley, pasture, barley repeated (R2) and pasture, fallow, wheat, barley, repeated (R3). Ploughing practices adopted for the various rotations affected persistence and regeneration. Not all ofthe seed that was produced in 1978 produced seedlings. A much lower proportion of the seed reserve of cv. Paragosa produced seedlings compared with cv. Robinson and cvv. Cyprus and Jemalong. The poorer re-establishment of cv. Paragosa could have been due to its more permeable seed compared with the other cultivars. Seed reserves persisted for a maximum of 7 years. Annual re-establishment was greater for all cultivars under the system of permanent pasture than under either the pasture, barley or the pasture, fallow, wheat, barley rotations which disturbed the soil. Unlike the other cultivars, germination and establishment rates of cv. Robinson were low following the first autumn rains in all years. Germination of this cultivar usually occurred from June to November following a delayed breakdown in hardseededness. It also responded to cultivation so that with the exception of R2 in 1980, the highest annual plant populations in R2 and R3 were in the cropping and/or fallowing phases rather than the pasture phases. Although cv. Paragosa produced the highest seed yield in the year of sowing, its reserves were exhausted by the third year in all rotations, whereas the harder seeded cultivars maintained adequate seed reserves to enable good plant re-establishment in the sixth year under all rotations, except in the continuous pasture rotation, where seed reserves of cv. Robinson were exhausted by the fifth year. Cultivation and consequent pod burial in the 2 cropping rotations preserved seeds longer than did the continuous pasture system. Jemalong maintained higher (P< 0.05) seed reserves than cvv. Cyprus and Robinson in the sixth year.

Effect of water stress on the phasic development of annual Medicago species

1976 ◽  
Vol 27 (2) ◽  
pp. 227 ◽  
Author(s):  
NM Clarkson ◽  
JS Russell
Keyword(s):  
Water Stress ◽  
Life Span ◽  
Mean Delay ◽  
Severe Water Stress ◽  
Eastern Australia ◽  
The Mean ◽  
Annual Medics ◽  
Annual Medicago ◽  
Delayed Flowering ◽  
Medicago Species

Although annual medics (Medicago spp.) grow and persist in subtropical eastern Australia, their growth in the field is greatly affected by water stress, which can occur at any time after germination. To study this effect in some detail, the phasic development of six annual Medicago cultivars was measured under four water regimes in a glasshouse. Stress was varied by allowing the soil to dehydrate to different degrees before rewetting, the cycles being repeated continuously. Water stress delayed flowering in all medics except M. scutellata, the mean delay being 14 days. Corresponding delays occurred in the onset of pod production. In contrast the later stages of phasic development were accelerated in some species. Both the length of flowering and life span of the M. truncatula cultivars were significantly reduced by water stress. In the case of cv. Jemalong, severe water stress reduced its length of flowering by 53 days and its life span by 27 days. These results suggest that annual medics have no mechanisms for evading dry seasonal conditions by earlier flowering, but once flowering has begun phasic development is accelerated in some species by water stress. The implications of this study for the interpretation and prediction of field behaviour of annual medics are that water stress can affect phasic development mainly through a delay in flowering. However, the effects appear to be small compared with those due to vernalization, photoperiod and temperature.

scholarly journals Differential expression of TLP, ERF1, and R2R3MYB in annual Medicago species under salinity conditions

2015 ◽  
Vol 14 (3) ◽  
pp. 10152-10164 ◽  
Author(s):  
F. Gharaghani ◽  
F. Rafiei ◽  
N. Mirakhorli ◽  
E. Ebrahimie
Keyword(s):  
Differential Expression ◽  
Annual Medicago ◽  
Medicago Species

An improved method for artificial hybridization in annual Medicago species

1994 ◽  
Vol 45 (7) ◽  
pp. 1329 ◽  
Author(s):  
W Pathipanawat ◽  
RAC Jones ◽  
K Sivasithamparam
Keyword(s):  
Success Rate ◽  
Fold Increase ◽  
Modified Technique ◽  
Established Method ◽  
Artificial Hybridization ◽  
Annual Medicago ◽  
Improved Technique ◽  
Medicago Species ◽  
First Time ◽  
Selection Of

An improved technique for successful artificial hybridization in annual medic (Medicago spp.) is described. Using a previously reported method, only four out of seven species were successfully crossed, with the percentage of success ranging from 3 to 22%. Initial modifications to this technique gave a 7-8 fold increase in the successful crossing rate in M. murex and M. polymorpha medic, from 9 to 64% with M. murex and from 10 to 82% with M. polymorpha. Further modifications to the technique resulted in a success rate of 100% in both species. The numbers of seeds per pod obtained from crosses in both species were also increased by using the modified techniques compared to the established method. Selection of larger, more mature flowers, differences in flower cutting position, as well as post pollination position were the main modifications which accounted for the greatly improved success rate. The modified technique was subsequently applied successfully to obtain for the first time inter-specific crosses involving M. polymorphax M. murex, M. polymorphax M. sphaerocarpos, M.murexx M. sphaerocarpos, M. solerolii x M. littoralis/M.truncatula hybrid, M. solerolii x M, tornata, and M. littoralis/M.truncatula hybrid x M. sphaerocarpos.

Patterns of seed softening and seedling emergence of nineteen annual medics during three years after a single seed crop in southern Queensland

1997 ◽  
Vol 37 (7) ◽  
pp. 767 ◽  
Author(s):  
D. L. Lloyd ◽  
G. B. Taylor ◽  
B. Johnson ◽  
K. C. Teasdale
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Farming Systems ◽  
The Other ◽  
Research Station ◽  
Hard Seed ◽  
Diurnal Cycles ◽  
Wide Range ◽  
Burr Medic ◽  
Annual Medics

Summary. To produce seed to determine the rates of seed softening of annual medics in the subtropics, 8 lines of barrel medic (Medicago truncatula), 3 lines of burr medic (M. polymorpha), 4 lines of snail medic (M. scutellata), and 1 line of each of button medic (M. orbicularis), strand medic (M. littoralis) and gama medic (M. rugosa) were grown at Warra in southern inland Queensland, in 1993. Seed of a fourth line of burr medic, a naturalised line, was harvested from Hermitage Research Station at that time. Pods were placed on the soil surface and buried at a depth of 7 cm, both in flywire envelopes and as free pods. Residual hard seed numbers were determined each year for 3 years from the envelopes, and seedlings were counted and removed from the free pods after each germination event. Patterns of softening of seeds from the same seed populations were also determined after placing them in a laboratory oven with a diurnal temperature fluctuation of 60/15° C for periods of 16, 40 and 64 weeks followed, after each time period, by 4 diurnal cycles of 35/10°C. More than 90% of the original seeds were hard. Seed softening at the soil surface ranged from 26% after 3 years in button medic to almost complete softening in the gama medic after only 2 years. Burial had little effect on the rate of softening of the button medic but about halved the rate of softening of the other lines. The barrel medics were vulnerable to losses of large numbers of seedlings which softened and germinated in January–February and the snail medics from seedlings emerging in August–December. The proportion of soft seeds recovered as seedlings in the buried compared with the surface pods was higher in the larger-seeded medics, snail and gama, and lower in the other, smaller-seeded medics. Laboratory techniques effectively ranked the medic lines for their rate of seed softening in the field and provided some insight into their seasonal patterns of seed softening. A wide range of seed softening patterns is available for fitting the requirements of various farming systems. The most appropriate pattern of softening will depend on the variability of medic seed production between years and the need for self regeneration of the medic after a cereal crop.

Residual effect of some herbicides on Medicago species in the Victorian Mallee

1972 ◽  
Vol 12 (55) ◽  
pp. 181
Author(s):  
GJ Wells
Keyword(s):  
Residual Effect ◽  
High Toxicity ◽  
Residual Toxicity ◽  
Application Rates ◽  
Annual Medics ◽  
Chemical Fallow ◽  
Medicago Species ◽  
Low Rate ◽  
Chondrilla Juncea

The use of soil persistent herbicides for controlling skeleton weed (Chondrilla juncea) on fallows and in crops might lead to problems of residual toxicity towards establishing medic pastures. Data from 1967 to 1969, taken from both chemical fallow and crop spray experiments on light soils in the Mallee, Victoria, are presented which show the extreme persistence of picloram applied at very low rates and its high toxicity towards both annual medics and lucerne. Other herbicides studied (an atrazine-amitrole mixture, fenac and 2, 4-D) had little or no effect at moderate application rates. It is considered that the very low rainfall in 1967 was largely responsible for the low rate of herbicide decomposition.

Effects of phosphorus on seed yields of subterranean clover, serradella and annual medics

1985 ◽  
Vol 25 (3) ◽  
pp. 595 ◽  
Author(s):  
MDA Bolland
Keyword(s):  
Seed Yield ◽  
Subterranean Clover ◽  
Average Weight ◽  
The Third ◽  
Hard Seeds ◽  
Annual Medics ◽  
Alternating Temperature ◽  
Seed Yields ◽  
The Relationship ◽  
Number Of Seeds

In three experiments located near Esperance, Western Australia, the effect of superphosphate phosphorus on seed yields of subterranean clover, serradella and annual medics was measured on newly-cleared soils, using low seeding rates. In two experiments, the relationship between seed yield and the amount of phosphorus applied was linear for subterranean clover and serradella; seed yields increasing by 7-24 kg/ha for each kg/ha of phosphorus applied, depending on species, strain or cultivar, and location. In the third experiment, seed yields of annual medic species also increased markedly with increasing amounts of applied superphosphate phosphorus, this response also depended on species and strain or cultivar, but the responses become less marked with increasing amounts of phosphorus. For the annual medic species, the phosphorus treatments had no effect on average weight of one burr, number of seeds per burr, weight of one seed, or the rate of softening of hard seeds as measured both in a 15/60� alternating temperature oven (one cycle/day) or for samples of burrs collected periodically during summer from the field. For all legumes, the appearance of first flowers was not affected by phosphorus treatment.

Strategies for control of Phoma black stem in annual Medicago species

1989 ◽  
Vol 29 (5) ◽  
pp. 635 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Disease Severity ◽  
Medicago Truncatula ◽  
Field Trial ◽  
Subsequent Development ◽  
Field Site ◽  
Infected Seed ◽  
Annual Medicago ◽  
And Control ◽  
Medicago Species ◽  
Selection Of

Strategies for control of Phoma black stem disease in annual Medicago species through selection of cultivars with increased resistance to Phoma medicaginis, fungicidal spray applications to swards, and fungicidal control of seedborne infection, were investigated. Fiftyseven annual Medicago cultivars and lines were screened for resistance in the field in 1 m rows over 2 consecutive seasons. There were significant differences in resistance among species and also between lines and cultivars of any particular species. Three M. rugosa cultivars were very highly resistant and most cultivars and lines showed some resistance. In a field trial, the fungicides benomyl, carbendazim, flutriafol, propiconazole, thiabendazole and triadimefon were tested for their efficacy in controlling Phoma black stem disease. All fungicides reduced disease severity in the sward and, except for thiabendazole, the percentage burrs with Phoma lesions. The role and control of seed-borne P. medicaginis in causing Phoma black stem disease in Medicago truncatula and M. polymorpha var. brevispina at a field site was also investigated. Seed-borne P. medicaginis caused subsequent development of Phoma black stem disease in swards sown with infected seed. Disease appeared earlier, developed faster and became much more severe in M. truncatula cv. Cyprus than in M. polymorpha cv. Serena. Application of benomyl seed treatments (0.1 and 0.5% w/w) resulted in only a 4-5 week delay in the onset of Phoma black stem symptoms.

Seed production and seed survival under grazing of annual medics (Medicago spp.) in north Syria

1988 ◽  
Vol 110 (3) ◽  
pp. 455-463 ◽  
Author(s):  
P. S. Cocks
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Native Species ◽  
Seasonal Pattern ◽  
Seed Survival ◽  
Medicago Rigidula ◽  
Good Guide ◽  
Annual Medics ◽  
Seed Yields ◽  
Striking Contrast

SummaryThree experiments which measured seed production and seed survival of annual medics (Medicago spp.) were conducted at Tel Hadya in north Syria. In Expts 1 and 2, conducted in consecutive years, the effects of rate and date of sowing on seed yield and its components were measured, while in Expt 3, the residual seed under summer grazing was monitored. In all three experiments seed permeability was observed at frequent intervals in summer and autumn. Selected ecotypes of three native medics (Medicago rigidula (L.) All., M. rotata Boiss. and M. noeana Boiss.) were compared with cultivars of M. truncatula Gaertn. and M. polymorpha (L.).Seed production was greatest at sowing rates of 20–40 kg/ha. The native species produced more seed (up to 1000 kg/ha) than the cultivars (less than 500 kg/ha), although not significantly so in the case of the late-flowering ecotype of M. noeana. Seed yields of 500–1000 kg/ha were considered to be sufficient to perpetuate the pastures, but even higher seed yields are desirable.Seed yield was closely related to number of pods in all ecotypes and, in Expt 2, up to 95% of flowers failed to produce mature pods. Flowers were more likely to mature at high sowing rate (256 kg/ha), in striking contrast to flower production itself which was greatest at sowing rates of less than 30 kg/ha. Flowers produced early in the season (before mid-April) were far more likely to give mature pods than late-produced flowers.In late October, seeds of the native species were less permeable (10%) than those of the cultivars (30%), although their permeability was similar to that of the cultivars in Australia. In the three experiments the seasonal pattern of permeability varied, although there was a tendency for seeds to gain permeability in autumn. In Expt 1 there was a strong suggestion that the change from impermeability to permeability was reversible.Ewes grazing mature pods gained weight, apparently as long as pod availability exceeded 10 kg/ha. It was clear that the condition of ewes was not a good guide to appropriate stocking rate for persistence of pastures, and that farmers will have to use other methods to assist them in grazing management.

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