Strategies to maximise establishment and production of oversown caucasian clover

Slow establishment of caucasian clover (Trifolium ambiguum L.) is hindering the use of this legume in pasture mixtures. Improved genetic material is one strategy of correcting the problem. Newly harvested seed of hexaploid caucasian clover germplasm covering a range of origins, together with white and red clover and lucerne, were sown in 1 m rows in a Wakanui soil at Lincoln in November 1995. After 21 days, the caucasian clover material as a group had similar numbers of emerged seedlings as white clover and lucerne, but was inferior to red clover. There was wide variation among caucasian clover lines (48-70% seedling emergence), with the cool-season selection from cv. Monaro ranked the highest. Recurrent selection at low temperatures could be used to select material with improved rates of seedling emergence. Red clover and lucerne seedlings produced significantly greater shoot and root dry weight than caucasian and white clover seedlings. Initially, caucasian clover seedlings partitioned 1:1 shoot to root dry weight compared with 3:1 for white clover. After 2 months, caucasian clover seedlings had similar shoot growth but 3 times the root growth of white clover. Between 2 and 5 months, caucasian clover partitioned more to root and rhizome growth, resulting in a 0.3:1 shoot:root ratio compared with 2:1 for white clover. Both clover species had similar total dry weight after 5 months. Unhindered root/ rhizome devel-opment is very important to hasten the establishment phase of caucasian clover. The caucasian clover lines KZ3 and cool-season, both selections from Monaro, developed seedlings with greater shoot and root growth than cv. Monaro. KZ3 continued to produce greater root growth after 5 months, indicating the genetic potential for improvement in seedling growth rate. Different pasture estab-lishment techniques are proposed that take account of the seedling growth characteristics of caucasian clover. Keywords: establishment, genetic variation, growth, seedling emergence, Trifolium ambiguum

Section: Discussionmentioning

confidence: 99%

Genetic variation for rate of establishment in caucasian clover

Widdup¹,

Knight²,

Waters³

1998

“…Research into inoculation and seed coating (Lowther 1975) led to collaborations between Invermay and private industry to establish New Zealand's seed coating processes (Lowther & Bonish 1980). Later developments in the inoculation (Pryor et al 1998) and establishment (Lowther et al 1998) of Caucasian clover and the interspecific hybrids with white clover (Widdup et al 2003) were also researched at Invermay.…”

Section: Pasture Production and Improvementmentioning

confidence: 99%

Agricultural innovation in East Otago: helping to shape New Zealand's farming industry

Stevens¹,

Cousins²

2006

The East Otago region has been at the forefront of agricultural advancement in New Zealand with key people leading the way in creating a culture of innovation. Rural technology developments are traced back from the emerging new biotechnology industries, through animal genetics research, improvements in hill country and pasture production, soil and fertiliser research, the introduction of deer farming and sheep breeding, to the frozen meat shipments, agricultural organisation restructuring and land reforms of the early settlers. Keywords: deer, genetics, grazing management, history, innovation, sheep, soil classification, soil fertility, technology

“…Rhizobia that effectively nodulate caucasian clover (Trifolium ambiguum) are not naturally present in New Zealand soils and inoculation with a specific strain of rhizobia (Rhizobium leguminosarum bv. trifolii) is essential (Lowther et al 1998). However, these rhizobia can form nodules on white clover (T. repens) that fail to fix N 2 .…”

Section: Introductionmentioning

confidence: 99%

Caucasian clover rhizobia are not a threat to nitrogen fixation by white clover

Pryor¹,

Lowther²

2004

Self Cite

Caucasian clover has specific rhizobial requirements, and inoculation with a recommended strain is essential for nodulation and symbiotic N2 fixation. However, these rhizobia form nodules on white clover which do not fix nitrogen i.e. are ineffective. At the Nelson NZGA conference, Elliot and co-workers cautioned that caucasian clover rhizobia may over time reduce N2 fixation by white clover in New Zealand pastures. We have shown that high populations of caucasian clover rhizobia build up in the soil under swards of caucasian clover with numbers ranging from 103 to 106/g soil. A field trial was established on a site containing a naturalised population of rhizobia nodulating white clover (105 rhizobia/g soil). Treatments were imposed by mixing caucasian clover rhizobia into the soil, so that they made up 0, 50% or 99% of the clover rhizobia population. The trial was then sown with uninoculated white clover seed. The planned levels of caucasian clover rhizobia were present after 1 month and there was only a small decline in numbers up to 22 months after sowing. White clover rhizobia increased over the first 14 months at least 10-fold, to 106/g soil, even in the presence of caucasian clover rhizobia. There were no significant effects on white clover forage yield or on the calculated amount of N2 fixed, even when soil populations of caucasian clover rhizobia made up 99% of the population of clover rhizobia at sowing. This lack of effect could be explained by the small percentage (up to 5%) of nodules on white clover formed by caucasian clover rhizobia. There is no doubt that high populations of caucasian clover rhizobia will develop in New Zealand soils with the increased use of caucasian clover and its associated rhizobia, but the presence of these rhizobia did not reduce symbiotic N2 fixation of white clover in this field experiment. Keywords: caucasian clover, competition, nitrogen fixation, nodulation, rhizobia, Trifolium ambiguum, Trifolium repens, white clover