Variation in Response to Moisture Stress of Young Plants of Interspecific Hybrids between White Clover (T. repens L.) and Caucasian Clover (T. ambiguum M. Bieb.)

Athole Marshall,Matthew Lowe,Rosemary Collins

doi:10.3390/agriculture5020353

Athole Marshall, Matthew Lowe + Show 1 more

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https://doi.org/10.3390/agriculture5020353

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Abstract

Backcross hybrids between the important forage legume white clover (Trifolium repens L.), which is stoloniferous, and the related rhizomatous species Caucasian clover (T. ambiguum M. Bieb), have been produced using white clover as the recurrent parent. The effect of drought on the parental species and two generations of backcrosses were studied in a short-term glasshouse experiment under three intensities of drought. Plants of Caucasian clover maintained a higher leaf relative water content and leaf water potential than white clover at comparable levels of drought, with the response of the backcrosses generally intermediate between the parents. Severe drought significantly reduced stolon growth rate and leaf development rate of white clover compared to the control, well-watered treatment, whilst differences between these two treatments in the backcross hybrids were relatively small. The differences between parental species and the backcrosses in root morphology were studied in 1m long vertical pipes. The parental species differed in root weight distribution, with root weight of Caucasian clover significantly greater than white clover in the 0.1 m to 0.5 m root zone. The backcrosses exhibited root characteristics intermediate between the parents. The extent to which these differences influence the capacity to tolerate drought is discussed.

Highlights

Changing climatic conditions mean that the growing demand for meat and milk based products must be met against a backdrop of rising global temperatures and changing patterns of precipitation [1]
For most of the growth parameters measured there were significant effects of population and drought, and significant population × drought interactions, but no significant differences between genotypes within populations (Table 1)
It has been predicted that climate change will affect the distribution patterns of rainfall [29] and that this may have a negative impact on grassland productivity [30]

Summary

Introduction

Changing climatic conditions mean that the growing demand for meat and milk based products must be met against a backdrop of rising global temperatures and changing patterns of precipitation [1]. Grassland systems face similar challenges from climate change, the development of new varieties of forage grasses and legumes better able to tolerate periods of drought is crucial. The most important forage legume component of temperate pastures is white clover (Trifolium repens L.) [8], a nitrogen fixing species that produces forage of high quality. It is an outbreeding, highly heterozygous allotetraploid (2n = 4x = 32) species and the wide genetic variation within its gene pool has been used successfully in the production of new varieties with improvements in many traits

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