DISTRICT PLANNING AND LAND USE

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CHALLENGES FACING GRASSLAND FARMING

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FIELD DAY

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Adaptation of Trifolium repens × T. uniflorum hybrid clovers to drought stress

White clover (Trifolium repens L.) is valued for its contribution to pasture quality and utilisation by animals, compatibility with grass, and fixation of nitrogen. However, it is limited by poor adaptation to drought. Hybridisation with Trifolium uniflorum L. may have potential to improve the drought resistance of white clover. An experiment in a rain shelter facility with contrasting moisture treatments, and a field evaluation under dryland conditions, were used to compare the agronomic potential of these interspecific hybrids (ISH) with white clover in moisture limited conditions. In the rain shelter experiment, there were smaller effects of water stress on shoot dry weight (DW), leaf area, internode length and senescence of first backcross generation hybrids compared with white clover and second backcross generation hybrids. Differences in photosynthetic responses were possibly influenced by the effect of root DW allocation on water uptake. In the field evaluation, growth scores of a wider range of hybrid families during summer moisture stress concurred with the results under water stress in the rain shelter. Growth of some ISH families outperformed the best white clover cultivars, particularly in the third and most stressful summer and this result was a key performance indicator of the value of the hybrids for drought prone areas. These findings using early, unselected, hybrid populations indicate the potential for further selection of elite, adapted cultivars from ISH breeding strategies. Keywords: Interspecific clover hybrid, drought resistance, rain shelter, field evaluation

Challenges facing the farmers of Central Otago

The Central Otago region, with its cold winters and hot summers, and valley floors with uplift mountains is definitely "a world of difference". At the NZGA conference in Alexandra in 1966 John Hercus stated "Central Otago has a lure which sets it apart from the rest of New Zealand. Its characteristics of geology, topography and climate, its history of occupation and exploitation, its scenery at once forbidding and yet strangely fascinating - these features combine to cast a spell which few who have been exposed, can ever fully escape" (Hercus 1966). The region and its high country have an iconic status epitomised by the "Southern Man" stereotype. This places Central Otago deep in the psyche of the nation. With this goes a unique and significant set of conditions under which farming must take place. Not only does the region have the biophysical challenges of soils, water and climate to contend with, but a wider set of values, often imposed from elsewhere. Fifty years after that first conference we remain challenged. What are the opportunities in front of us and how should we best accommodate the challenge of maintaining a viable enterprise and at the same time, respecting the intense public and customer interest in our use of land and livestock? Central Otago and the associated high country of the Lakes district and McKenzie basin can be divided into three farming types. These are the valley floor irrigable type, the flat and downland dryland regions, and the high country. Each of these has challenges that are at times unique, but often overlap with problems faced in other regions.

Central Otago - Built on gold, growing on grass.

A warm welcome to our "World of Difference" to all delegates attending this conference - we hope your stay is enjoyable and that you will leave Central Otago with an enhanced appreciation of the diversity of land use and the resilient and growing economic potential that this region has to offer. Without regional wellbeing the national economy will struggle to grow, something Central Government finally seems to be realising, and the Central Otago District Council Long Term Plan 2012-2022 (LTP) signals the importance of establishing a productive economy for the local community which will aid in the economic growth of the district and seeks to create a thriving economy that will be attractive to business and residents alike. Two key principles that underpin the LTP are sustainability and affordability, with the definition of sustainability being "… development that meets the needs of the present without compromising the ability of future generations to meet their own needs."

Nutrient requirements for irrigated lucerne in Central Otago

Two field trials were commenced in September 2000 on newly sown irrigated lucerne near Tarras in Central Otago. The first trial measured the effects of phosphorus (P) (0, 30, 60, 120 kg P/ha) and potassium (K) (0, 50, 100, 200 kg K/ha) fertiliser applications while the second trial determined nitrogen (N) requirements for lucerne establishment. Initial soil test levels (0-75 mm) were pH 5.6, Olsen P 15 μg/ml; quicktest (QT) K 6 and sodium tetra-phenol-boron extractable K (TBK) 3.1. Lucerne production averaged 9.5 t dry matter (DM)/ha in the establishment year, 15.6 t DM/ ha in Year 2 and 14.8 t DM/ha in Year 3. There were no annual DM responses to any of the three fertilisers applied regardless of the rate of application. Despite the control mean annual herbage P concentrations being within the optimum range of 0.20-0.25% the application of P fertiliser significantly increased the P concentrations (P

Variation in the reproductive development of perennial ryegrass (Lolium perenne L.) cultivars

Plant breeding has manipulated the flowering behaviour of perennial ryegrass (Lolium perenne L.) by developing later-heading cultivars. However, the impacts of breeding on the intensity and temporal distribution of flowering are not known. This study compared the reproductive development of 23 perennial ryegrass cultivar/endophyte combinations. In the Waikato and Canterbury, two replicate plots were closed from grazing and tillers were collected every two weeks over a 10-week period during late spring and early summer. Plant development stage was determined for each tiller using a quantitative scale, which was then used to calculate the mean stage count of each cultivar. The rate and timing of reproductive development differed among cultivars. Mid-maturing cultivars matured earlier at both sites compared with late- and very late-maturing cultivars. While the intensity of flowering was similar between maturity groups, the temporal distribution of flowering varied: the late- and very late-maturing cultivars had lower proportions of reproductive tillers early in the season. Keywords: Lolium perenne L., reproductive development, flowering behaviour

Novel approaches to improving growth of pasture legumes at low phosphorus levels

Strategies to reduce the economic and environmental costs of phosphate (P) fertiliser use in mixed pastures through plant breeding are focussed on inefficiencies in the legume component. One approach is breeding within white clover for root systems with improved P acquisition properties. Selection for root length per unit root weight (specific root length, SRL) showed that higher SRL plants could retain more biomass in the above ground fraction with decreasing soil P, whereas plants with lower SRL diverted more biomass to roots. Back cross 1 (BC1) generation interspecific hybrids between white clover and a wild relative, Trifolium uniflorum L., may possess additional root traits influencing P acquisition. In glasshouse experiments, some T. repens × T. uniflorum hybrids, back-crossed to white clover, also exhibited higher shoot dry weight than their white clover cultivar parents at low nutrient supply levels and low to intermediate soil Olsen P. This, combined with low internal P concentrations, suggests some BC1 hybrids may be more tolerant of low soil P than white clover. Differences in both P acquisition ability and internal P use efficiency may contribute to the observed yield differences. There are good prospects for delivery of new-generation clover cultivars with improved phosphate use efficiency to New Zealand farmers. Keywords: phosphorus, white clover, Trifolium uniflorum, interspecific