The response to selection for increased nodule tissue in white clover (Trifolium repens L.)

1971 ◽  
Vol 35 (1) ◽  
pp. 17-25 ◽  
Author(s):  
L. R. Mytton ◽  
D. Gareth Jones
1996 ◽  
Vol 6 ◽  
pp. 141-143
Author(s):  
D.R. Woodfield ◽  
J.R. Caradus ◽  
G.R. Cousins ◽  
T. Dunn

Increased taproot diameter is an important component in maintaining white clover (Trifolium repens L.) growth, nitrogen fixation and persistence during short-term moisture stress. Previous reports indicated selection for large taproot diameter would result in commensurate increases in leaf size and poorer growth habit. The current research investigates the response to selection for taproot diameter and the association between taproot diameter and leaf size in large-leaved clovers suited to dairy grazing systems. Taproot diameter increased by 2.4% per cycle while leaf size and growth habit were not significantly altered. Furthermore, while taproot diameter did not increase between cycle 2 and 3, the root index which measures the ratio of taproot diameter to leaf size increased linearly across all three cycles. These results suggest it is possible to select white clovers for dairying which have larger taproot diameter while maintaining a suitable growth habit. Keywords: dairying, drought, genetic improvement, root morphology, Trifolium repens L., white clover,


1988 ◽  
Vol 110 (1) ◽  
pp. 145-154 ◽  
Author(s):  
R. Cook ◽  
D. R. Evans

SummaryThe expression of symptoms of stem nematode reproduction on a total of 53 white clovers (26 cultivars, 14 genepools and 13 introductions from plant collections) was studied in a series of field and glasshouse experiments. Seedlings or stolon-tip cuttings were inoculated with nematodes and the clovers classified by the proportion of plants which developed symptoms. Significant differences were found between varieties although in each test the majority was intermediate between more resistant and susceptible extremes. There was significant positive correlation between tests, in spite of different inoculation methods and different average levels of susceptibility. Very large-leaved cv. Aran was more resistant than most other clovers tested, and small-leaved cv. S. 184 was more susceptible. There was no general correlation of leaf size with reaction to stemnematode. Small-leaved cv. Pronitro was also resistant while several large-leaved cultivars were susceptible. In observations of plants exposed to nematodes over a long period, either by sequential inoculations or through perpetuating latent infections, apparently resistant plants eventually succumbed and supported nematode reproduction. It has not been determined whether this was because selection for virulence in the nematodes had occurred.


Author(s):  
D.R. Woodfield ◽  
J.R. Caradus

In a series of four experiments, the w-seeding ability and shoot and root characteristics of dryland white clover populations (Trifolium repens L.), and the effect of selection for root characteristics within white clover were examined. There was little evidence that dryland populations were better at re-seeding than Huia, but dryland populations were more taprooted than populations collected from moister environments. Root morphologies of dryland populations were similar to that of Huia but were smaller leaved, although not as small leaved as Tahora. Evidence that selection for more taprooted, smaller-leaved types of white clover would be successful is also presented. Keywords: root type, drought, re-seeding, plant breeding, survival


Author(s):  
D.R. Woodfield ◽  
I.J. Baird ◽  
P.T.P. Clifford

Improving the seed yield potential of new white clover (Trifolium repens L.) cultivars is critical to their commercial viability and to overcoming the increasing pressures from land use change in Canterbury. The genetic control and response to selection was investigated for two seed yield characteristics, inflorescence density (no./m2) and seed yield per inflorescence (g/ inflorescence). Inflorescence density and seed yield per inflorescence were both responsive to selection and acted independent of one another to increase seed yield. Selection for high inflorescence density resulted in 34% higher seed yield than the low inflorescence density selection. This change in seed yield was associated with a 33% higher inflorescence density, while seed yield per inflorescence was unchanged. Similarly, selection for seed yield per inflorescence resulted in a 17% difference in seed yield between the high (HYI) and low (LYI) seed yield per inflorescence selections. This change in seed yield was associated with a 24% higher yield per inflorescence for the HYI selection, while inflorescence density remained unchanged. These results confirm that both mechanisms are under independent genetic control and can be utilized to increase seed yield of new white clover cultivars. Keywords: genetics, inflorescence density, seed production, Trifolium repens, white clover


Plant Science ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 531-539 ◽  
Author(s):  
Elizabeth S. Jones ◽  
Leonie J. Hughes ◽  
Michelle C. Drayton ◽  
Michael T. Abberton ◽  
Terry P.T. Michaelson-Yeates ◽  
...  

2007 ◽  
Vol 277 (4) ◽  
pp. 413-425 ◽  
Author(s):  
N. O. I. Cogan ◽  
M. C. Drayton ◽  
R. C. Ponting ◽  
A. C. Vecchies ◽  
N. R. Bannan ◽  
...  

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