scholarly journals GENETIC VARIATION FOR TEMPERATURE RESPONSE IN ALFALFA (MEDICAGO SATIVA L.)

1980 ◽  
Vol 60 (2) ◽  
pp. 547-554 ◽  
Author(s):  
R. J. McLAUGHLIN ◽  
B. R. CHRISTIE
Keyword(s):  
Genetic Variation ◽  
High Temperature ◽  
Medicago Sativa ◽  
Temperature Response ◽  
Field Performance ◽  
Field Trials ◽  
Growth Room ◽  
Medicago Sativa L ◽  
High Yields ◽  
Response To Temperature

Physiological studies had indicated that low mid-summer yields of alfalfa (Medicago sativa L.) can be attributed to high temperature. A program was initiated to study genetic variation for response to high temperatures. Two thousand genotypes were grown from seed in the growth room at 20/15 °C, harvested twice, then grown at 30/25 °C for two more harvests. A great deal of variation among genotypes was found to exist for response to temperature. Genotypes that were found to yield well at higher temperatures tended to be early-maturing with few stems per plant. Genotypes that yielded well at low temperatures tended to be later in maturity and to have a large number of stems. Based upon dry matter yields, 300 genotypes were selected to represent differences in responses, namely: 100 had high yields at high temperature only; 100, high at low temperature only; and 100, high at both temperatures. These selections were transplanted to the field for subsequent field trials to substantiate growth room findings. Little or no relationship was found between growth room performance and field performance. This lack of association was due in part to winter injury experienced the first year. In addition, temperatures experienced in the field were much lower than those used indoors.

GENETIC VARIATION FOR FORAGE QUALITY OF ALFALFA STEMS

1987 ◽  
Vol 67 (4) ◽  
pp. 1057-1067 ◽  
Author(s):  
D. R. BUXTON ◽  
G. C. MARTEN ◽  
J. S. HORNSTEIN
Keyword(s):  
Cell Wall ◽  
Genetic Variation ◽  
Medicago Sativa ◽  
Crude Protein ◽  
Nutritive Value ◽  
Growth Traits ◽  
Forage Quality ◽  
In Vitro Digestibility ◽  
Medicago Sativa L

When normally harvested for hay, the basal portion of alfalfa (Medicago sativa L.) stems is low in forage quality. This study was conducted to determine whether genetic variation for in vitro digestible dry matter (IVDDM) and crude protein (CP) concentration of stems of perennial Medicago spp. could be identified and whether morphological and chemical traits were associated with variation in these characteristics of stems. The lower six nodes and internodes of stems and total herbage from 64 Plant Introduction (PI) accessions and five cultivars of field-grown plants were harvested twice when most plants were at the early seed-pod stage of maturity. Several morphological and growth traits were measured, and both stems and total herbage were evaluated for IVDDM and CP concentration. Covariant analysis was used to adjust in IVDDM and CP concentration of stems for differences in plant maturity. Significant variation for IVDDM and CP concentration in stems existed among the cultivars and among the accessions. Some accessions had significantly higher stem IVDDM or CP concentration than control cultivars. The M. sativa accession, PI 440496, had the fourth highest stem IVDDM and third highest stem CP, with concentrations of 374 and 79 g kg−1, respectively. The number of ridges on stems (stem shape) was significantly correlated with stem IVDDM and CP concentration with average correlation coefficients of 0.30 and 0.35, respectively. Cell-wall concentration and lignin concentration per unit cell wall of stems were both negatively correlated with stem IVDDM and CP concentration. Selection for improved nutritive value of stems may have potential for improving the nutritive value of alfalfa herbage.Key words: Alfalfa, forage quality, crude protein, in vitro digestibility, Medicago sativa L.

scholarly journals Variation Between Cut Chrysanthemum Cultivars in Response to Suboptimal Temperature

2007 ◽  
Vol 132 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Anke van der Ploeg ◽  
Ranathunga J.K.N. Kularathne ◽  
Susana M.P. Carvalho ◽  
Ep Heuvelink
Keyword(s):  
Growth Rate ◽  
Genetic Variation ◽  
Temperature Response ◽  
Dry Weight ◽  
Stem Length ◽  
Long Day ◽  
Cultivation Period ◽  
Optimum Response ◽  
Total Dry Weight ◽  
Response To Temperature

To breed for more energy-efficient cut chrysanthemum (Chrysanthemum morifolium Ramat.) cultivars it is important to know the variation of the temperature response existing in modern cultivars. In a greenhouse experiment with 25 chrysanthemum cultivars, a significant variation was observed in temperature response (16 °C or 20 °C) for reaction time, total dry weight produced, stem length, and flower size and number. To study this genetic variation in temperature response over a larger range of temperatures (15 °C to 24 °C), four contrasting cultivars (Annecy, Delianne, Reagan, and Supernova) were selected in a second experiment. Furthermore, a third experiment was performed in which the cultivation period was split into three phases and the influence of temperature in each of these phases was studied for the four selected cultivars. Dry weight production in all cultivars was very sensitive to temperature during the long day period. Relative growth rate showed an optimum response to temperature, with the optimum around 24 °C. Net assimilation rate also showed an optimum response to temperature, whereas leaf area ratio increased linearly with temperature. Compared with these temperature effects during the long day, the effect of temperature on absolute growth rate during the short day was, depending on the cultivar, relatively small or even absent. The reaction time, on the other hand, was very temperature sensitive, showing an optimum that was cultivar dependent. The temperature response of the total dry weight production during the whole cultivation period was, therefore, very cultivar dependent. Furthermore, depending on the cultivar, stem length increased with temperature, especially during long day, as a result of both increasing internode number and average internode length. The response of both flower size and number to temperature was also highly cultivar specific. The possibilities of using this genetic variation for breeding are discussed.

scholarly journals Analysis of effects in wheat of high temperature on grain filling attributes estimated from mathematical models of grain filling

2003 ◽  
Vol 141 (2) ◽  
pp. 203-212 ◽  
Author(s):  
M. ZAHEDI ◽  
C. F. JENNER
Keyword(s):  
High Temperature ◽  
Mathematical Models ◽  
Logistic Model ◽  
Inflection Point ◽  
Genotypic Variation ◽  
Temperature Response ◽  
Grain Filling ◽  
Temperature Tolerance ◽  
Grain Weight ◽  
Response To Temperature

Compared with growth at 20/15°C (day/night), exposure of wheat (Triticum aestivum L.) plants to moderately high temperature (30/25°C) significantly decreased grain weight through shortening the duration of grain filling, combined with small (or no) positive increases in the rate of grain filling. Several mathematical models of grain filling were assessed for their suitability as means of analysing these effects of temperature. The ordinary logistic model was found to be the most appropriate model and was used for the analysis of grain filling responses in four cultivars differing in their responses. Genotypic variation in response to temperature was observed for both rate and duration of grain filling, but the variation for the duration of grain filling among cultivars was small at the higher temperature. Significant correlation was found between single grain weight with the rate, but not with the duration, of grain filling at high temperature, which indicated an important role for synthetic processes involved in grain filling in the temperature sensitivity of wheat cultivars. As they are independent traits, both rate and duration are required selection criteria for the improvement of heat tolerance. Responses of one attribute estimated from the logistic model, the inflection point of the course of grain filling, may give insight into a temperature response that is distinguishable from that associated with the duration of grain filling. The inflection point appears to be worth including as a criterion in selecting for high temperature tolerance in wheat.

SCREENING FOR IMPROVED STAND ESTABLISHMENT IN RUSSIAN WILD RYEGRASS

1980 ◽  
Vol 60 (4) ◽  
pp. 1171-1177 ◽  
Author(s):  
K. H. ASAY ◽  
D. A. JOHNSON
Keyword(s):  
Genetic Variation ◽  
Seedling Emergence ◽  
Field Performance ◽  
Moisture Stress ◽  
Field Trials ◽  
Phenotypic Variance ◽  
Seedling Vigor ◽  
Planting Depth ◽  
Stand Establishment ◽  
Made In

Laboratory and field trials were conducted to determine the extent of the genetic variation among 134 Russian wild ryegrass (Elymus junceus Fisch.) progeny lines for characters related to stand establishment under semiarid conditions. Progenies were evaluated in the laboratory for seedling emergence and subsequent vigor using a 7.6-cm planting depth, seedling emergence under controlled soil moisture stress, and seedling recovery after exposure to drought. Significant genetic variation was detected for emergence, seedling vigor, and stand establishment in the field and for all measurements made in the laboratory except seedling recovery after drought. The genetic variance comprised from 50 to 60% of the total phenotypic variance in most instances. Emergence and subsequent seedling vigor from a 7.6 cm planting depth were the most closely related to data collected in the field (r = 0.17–0.33**). Results from the other laboratory trials were not significantly correlated with field performance.

scholarly journals Genetic variation for seed yield and its components in alfalfa (Medicago sativa L.) populations

Agronomie ◽  
2000 ◽  
Vol 20 (3) ◽  
pp. 333-345 ◽  
Author(s):  
Eduardo-Daniel Bolaños-Aguilar ◽  
Christian Huyghe ◽  
Bernadette Julier ◽  
Christian Ecalle
Keyword(s):  
Genetic Variation ◽  
Medicago Sativa ◽  
Seed Yield ◽  
Medicago Sativa L

Genetic variation for disease and nematode resistances and forage quality in perennial diploid and tetraploid lucerne populations (Medicago sativa L.)

Euphytica ◽  
1996 ◽  
Vol 91 (2) ◽  
pp. 241-250
Author(s):  
B. Julier ◽  
P. Guy ◽  
C. Castillo-Acuna ◽  
G. Caubel ◽  
C. Ecalle ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Medicago Sativa ◽  
Forage Quality ◽  
Medicago Sativa L

Selection for resistance to the root-lesion nematode in alfalfa

1992 ◽  
Vol 72 (2) ◽  
pp. 593-598
Author(s):  
B. R. Christie ◽  
J. L. Townshend
Keyword(s):  
Medicago Sativa ◽  
Pratylenchus Penetrans ◽  
Root Lesion Nematode ◽  
Lesion Nematodes ◽  
Growth Room ◽  
Medicago Sativa L ◽  
Lesion Nematode ◽  
Selection For ◽  
Root Lesion Nematodes ◽  
Made In

A study was conducted to evaluate response of alfalfa (Medicago sativa L.) to selection for resistance to the root-lesion nematode (Pratylenchus penetrans (Cobb) Filipjev and Sch.-Stek.) under growth-room facilities. Six hundred plants of the cultivar Vernal were inoculated with root-lesion nematodes. Counts were made 13–14 wk later of the number of nematodes g−1 root. Selections were made for relatively low counts (resistant) and high counts (susceptible). Selections were self-pollinated, and the S1 progeny of nine plants (five resistant and four susceptible) were evaluated. The S1 progenies from both types of selections had similar counts. The S2 progenies of resistant S1 parents, however, had lower counts than those of susceptible parents. The F1 crosses generally reacted as expected on the basis of the S2 parents. Results of this study suggest that progress can be made in breeding for resistance to the root-lesion nematode in alfalfa.Key words: Nematode, Pratylenchus penetrans, alfalfa, selection

Production and field performance of transgenic alfalfa (Medicago sativa L.) expressing alpha-amylase and manganese-dependent lignin peroxidase

Euphytica ◽  
1995 ◽  
Vol 85 (1-3) ◽  
pp. 381-393 ◽  
Author(s):  
S. Austin ◽  
E. T. Bingham ◽  
D. E. Mathews ◽  
M. N. Shahan ◽  
J. Will ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Lignin Peroxidase ◽  
Field Performance ◽  
Alpha Amylase ◽  
Transgenic Alfalfa ◽  
Medicago Sativa L

Molecular analysis of genetic variation among alfalfa (Medicago sativa L.) and Medicago ruthenica clones

2000 ◽  
Vol 80 (4) ◽  
pp. 773-779 ◽  
Author(s):  
T. A. Campbell
Keyword(s):  
Genetic Variation ◽  
Medicago Sativa ◽  
Genetic Relatedness ◽  
Physiological Stress ◽  
Random Amplified Polymorphic Dna ◽  
Genetic Distances ◽  
Medicago Ruthenica ◽  
Medicago Sativa L ◽  
Bridge Crossing ◽  
Simple Sequence

Medicago ruthenica (L.) Ledebour is an allogamous diploid (2n = 2x = 16) perennial indigenous to Siberia, Mongolia and Manchuria with a remarkable ability to survive mechanical and physiological stress. The possibility of hybridizing alfalfa (Medicago sativa L.) and M. ruthenica is being investigated. The objective of the current research was to conduct a molecular assessment of genetic relatedness and inter- and intra-specific genetic variation in cultivated alfalfa (2n = 4x = 32) and M. ruthenica. Seventeen alfalfa clones, selected randomly from the broad-based population W10- AC3, and 17 agronomically superior M. ruthenica clones, tracing to 17 collection sites in Inner Mongolia, were studied using Random Amplified Polymorphic DNA (RAPD), Anchored Microsatellite Priming (AMSP), and Simple Sequence Repeat (SSR) analyses of genomic DNA. Mean genetic distances (GD) within M. ruthenica and alfalfa clones were 0.5 and 0.56, respectively, based on RAPD/AMSP data, and 0.29 and 0.40, respectively, based on SSR data. Alfalfa and M. ruthenica were genetically distant (RAPD/AMSP GD = 0.73); however, this difference does not necessarily preclude the possibility of interspecific hybridization, although the use of techniques such as bridge crossing, embryo culture rescue and/or protoplast fusion may be necessary. Key words: Alfalfa, genetic resources, Medicago ruthenica, Medicago sativa, microsatellite, simple sequence

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