A commercial solid matric priming method and an osmotic priming method were used to measure seed priming responses of birdsfoot trefoil, kura clover, and sericea lespedeza. Differences were not observed using standard germination tests, but both priming methods show potential for increased germination rate (P>0.05). Conflicting results for matric and osmotic priming were found in terms of seed storage potential after priming, with matric primed seeds showing higher (P<0.05) germination after accelerated aging and osmotic primed seeds showing significant lower germination(P<0.01). Birdsfoot trefoil benefited from priming, but responses varied by priming treatment, while kura clover showed less response to both priming treatments. In a field study comparing matric primed vs. unprimed seedling emergence, matric priming effects were small and these data suggest that solid matrix priming may be unlikely to improve the field establishment of either species. Aqueous smoke solutions were also tested for effect on seed germination. Differences in final germination percent due to solution type (after exposure to liquid smoke solutions for 10- or 45-min) were not observed. Highest concentration of the 10-min solution treatment reduced (P<0.05) birdsfoot trefoil germination. Greater germination was observed only for 'Perfect Fit' kura clover treated with low or intermediate concentrations of either solution. High concentrations of 10-min smoke water increased time to 50% germination (T50) for all seeds, but some reduction in T50 occurred for kura clovers treated with low (5%) solution concentrations. The 45-min treatments had little effect on germination rates. Applying aqueous smoke solution to seeds at germination did not improve germination responses of these forage legume species. / Master of Science

A number of morphological, floral, rhizome, root and herbage characteristics were studied in order to describe genetic variation and environmental responses in T. ambiguum. From each of six lines, 30 genotypes were clonally progagated into five diverse edaphic and altitudinal sites and grown for one season. Comparisons of growth and form were also made between T. ambiguum, T. repens cv. 'Grasslands Huia' and Lotus pedunculatus cv. 'Grasslands Maku'. The polyploid lines were found to have larger leaves than the diploids while all the lines of T. ambiguum had larger leaves than did white clover. Tetraploid lines had longer petioles and were taller and more erect than the diploids or hexaploids. Floral initiation was found to become later as ploidy level increased but the tetraploid lines exhibited a very large variation in flowering date. The cultivar Treeline was found to produce the most herbage under all conditions although not significantly more than cultivar Prairie or C.P.I. 57353. However, as nodulation was not studied it was not possible to determine whether variety differences were due to root nodulating ability or some other genetically determined parameter. None of the T. ambiguum varieties produced as much herbage as cv. Huia or cv. Maku at any site. However, all the T. ambiguum lines performed relatively better under harsher conditions. Because a large proportion of T. ambiguum was below ground the best T. ambiguum line, cultivar Treeiine, produced equivalent total plant dry weight to cv. Huia and cv. Maku at 1200 m. a.s.l., the high altitude site. Cultivar Prairie was found to have the highest proportion of rhizomes to total plant mass bu because cv. Treeline had higher total plant dry weight both cultivars produced equivalent mean rhizome dry weight. The number of rhizomes, number of daughter plants and rhizome dry weight were all highly correlated and these three characteristics showed similar trends among varieties. Rhizome length was found to increase with ploidy level, as did rhizome internode length. However, the number of nodes was found to be higher in the diploids than in the polyploids. Cultivar Treeline was found to have a high proportion of branching nodes on its rhizomes while C.P.I. 57353 and cv. Summit had the least. Rhizome production was restricted in the Wakanui silt loam soil of high bulk density. However, herbage growth and rhizome branching was increased, probably because of the higher fertility. It was shown using factor analysis on genotypic correlations, that rhizome characteristics and herbage yields were relatively independently inherited. However, morphological characters tended to be related to herbage yields. The polyploid varieties were found to be more genetically variable than the diploids . Broad sense heritabilities were calculated for all parameters measured, and in general, morphological characteristics had higher values than agronomic characteristics. As the genetic variation within each line was higher than the variation among lines, it is apparent that selection within lines should result in the largest gains. Therefore, comparison of the mean performance of the presently highly variable lines is relatively uninformative. By sacrificing some genetic diversity, large gains could be made in performance. It is suggested that cv. Prairie be used as the basis for selecting a highly rhizomatous cultivar while cv. Treeline could be used in the selection of a cultivar with higher herbage production suitable for high country conditions. In a second trial, an established stand of cv. Treeline produced up to 13250 kg per ha for one season under good growing conditions. The management required to produce this amount of herbage was to irrigate and cut to ground level every two months. The growth rate was considerably depressed when cut monthly. It was also shown that root and rhizome yield reached 12600 kg per ha, indicating a massive reserve of assimilates, particularly useful for surviving periods of stress. Seed yields were found to be adequate, reaching levels equivalent to 500-700 kg per ha. These results were discussed in relation to earlier observations on T. ambiguum by workers in Russia, Australia, U.S.A. and New Zealand. Suggestions were made for further genetic and agronomic testing.

A number of morphological, floral, rhizome, root and herbage characteristics were studied in order to describe genetic variation and environmental responses in T. ambiguum. From each of six lines, 30 genotypes were clonally progagated into five diverse edaphic and altitudinal sites and grown for one season. Comparisons of growth and form were also made between T. ambiguum, T. repens cv. 'Grasslands Huia' and Lotus pedunculatus cv. 'Grasslands Maku'. The polyploid lines were found to have larger leaves than the diploids while all the lines of T. ambiguum had larger leaves than did white clover. Tetraploid lines had longer petioles and were taller and more erect than the diploids or hexaploids. Floral initiation was found to become later as ploidy level increased but the tetraploid lines exhibited a very large variation in flowering date. The cultivar Treeline was found to produce the most herbage under all conditions although not significantly more than cultivar Prairie or C.P.I. 57353. However, as nodulation was not studied it was not possible to determine whether variety differences were due to root nodulating ability or some other genetically determined parameter. None of the T. ambiguum varieties produced as much herbage as cv. Huia or cv. Maku at any site. However, all the T. ambiguum lines performed relatively better under harsher conditions. Because a large proportion of T. ambiguum was below ground the best T. ambiguum line, cultivar Treeiine, produced equivalent total plant dry weight to cv. Huia and cv. Maku at 1200 m. a.s.l., the high altitude site. Cultivar Prairie was found to have the highest proportion of rhizomes to total plant mass bu because cv. Treeline had higher total plant dry weight both cultivars produced equivalent mean rhizome dry weight. The number of rhizomes, number of daughter plants and rhizome dry weight were all highly correlated and these three characteristics showed similar trends among varieties. Rhizome length was found to increase with ploidy level, as did rhizome internode length. However, the number of nodes was found to be higher in the diploids than in the polyploids. Cultivar Treeline was found to have a high proportion of branching nodes on its rhizomes while C.P.I. 57353 and cv. Summit had the least. Rhizome production was restricted in the Wakanui silt loam soil of high bulk density. However, herbage growth and rhizome branching was increased, probably because of the higher fertility. It was shown using factor analysis on genotypic correlations, that rhizome characteristics and herbage yields were relatively independently inherited. However, morphological characters tended to be related to herbage yields. The polyploid varieties were found to be more genetically variable than the diploids . Broad sense heritabilities were calculated for all parameters measured, and in general, morphological characteristics had higher values than agronomic characteristics. As the genetic variation within each line was higher than the variation among lines, it is apparent that selection within lines should result in the largest gains. Therefore, comparison of the mean performance of the presently highly variable lines is relatively uninformative. By sacrificing some genetic diversity, large gains could be made in performance. It is suggested that cv. Prairie be used as the basis for selecting a highly rhizomatous cultivar while cv. Treeline could be used in the selection of a cultivar with higher herbage production suitable for high country conditions. In a second trial, an established stand of cv. Treeline produced up to 13250 kg ha⁻¹ for one season under good growing conditions. The management required to produce this amount of herbage was to irrigate and cut to ground level every two months. The growth rate was considerably depressed when cut monthly. It was also shown that root and rhizome yield reached 12600 kg ha⁻¹, indicating a massive reserve of assimilates, particularly useful for surviving periods of stress. Seed yields were found to be adequate, reaching levels equivalent to 500-700 kg ha⁻¹. These results were discussed in relation to earlier observations on T. ambiguum by workers in Russia, Australia, U.S.A. and New Zealand. Suggestions were made for further genetic and agronomic testing.

This study consisted of two sheep grazed dryland pasture experiments. Experiment l compared sheep production from 3-year-old cocksfoot based pastures grown in combination with white, Caucasian, subterranean or balansa clover with a ryegrass-white clover pasture and a pure lucerne forage. Sheep liveweight gain per head from each pasture treatment and the pure lucerne stand was recorded in the 2006/07 and 2007/08 seasons. The cocksfoot-subterranean clover pasture provided equal (381 kg LW/ha in 2006) or higher (476 kg LW/ha in 2007) animal production in spring and gave the highest total animal production (646 kg LW/ha) averaged across years of the five grass based pastures. However, total annual liveweight production from lucerne was higher than any grass based pasture mainly due to superior animal production during summer when lucerne provided 42-85% higher animal production than any of the grass based pastures. In Experiment 2, the effect of stocking rate (8.3 (low) and 13.9 (high) ewes + twin lambs/ha) and time of closing in spring on lamb liveweight gain, pasture production and subterranean clover seedling populations was monitored over 2 years for a dryland cocksfoot-subterranean clover and ryegrass-subterranean clover pasture in Canterbury. In both years, twin lambs grew faster (g/head/d) in spring at low (327; 385) than high (253; 285) stocking rate but total liveweight gain/ha (kg/ha/d) was greater at high (7.26; 7.91) than low (5.43; 6.38) stocking rate. Ewes also gained 0.5 and 1.5 kg/head at the low stocking rate in 2006 and 2007 respectively but lost 0.2 kg/head in 2006 and gained 0.3 kg/head at high stocking rate in 2007. Mean subterranean clover seedling populations (per m²) measured in autumn after grazing treatments in the first spring were similar at both low (2850) and high (2500) stocking rate but declined with later closing dates in spring (3850, 2950, 2100 and 1700 at 2, 4, 6, 8 weeks after first visible flower). Seedling populations measured in autumn after grazing treatments in the second spring were also unaffected by stocking rate (low 1290, high 1190) but declined with later closing dates in spring (1470, 1320 and 940 at 3, 5 and 8 weeks after first flowering, respectively). The effect of stocking rate and closing dates in spring on pasture and clover production in the following autumn was similar to the effects on seedling numbers in both years. However, clover production in the following spring was unaffected by stocking rate or closing date in the previous year at the relatively high seedling populations generated by the treatments. This was presumably due to runner growth compensating for lower plant populations in pastures that were closed later in spring. Subterranean clover runner growth in spring may not compensate in a similar manner if seedling numbers in autumn fall below 500/m². Mean annual dry matter production from cocksfoot and ryegrass pastures grown with and without annual clovers pasture production ranged from 6.4 to 12.4 t DM/ha/y but stocking rate (8.3 vs. 13.9 ewes/ha) during spring did not affect annual pasture production. Pastures overdrilled with annual clovers yielded 23-45% more dry matter production than pastures grown without annual clovers. The study confirms the important role of subterranean clover in improving pasture production and liveweight gains of sheep in dryland cocksfoot and ryegrass pastures. Lowering stocking rate from 13.9 to 8.3 ewes/ha was a less effective method of increasing seed production of subterranean clover in dryland pastures although it did lead to increased liveweight gain per head.

The annual and seasonal water use efficiency of six pasture combinations were calculated from the ‘MaxClover’ Grazing Experiment at Lincoln University. Pastures have been established for six years and are grazed by best management practices for each combination. Measurements for this study are from individual plots of four replicates of ryegrass (RG)/white clover (Wc), cocksfoot (CF)/Wc; CF/balansa (Bal) clover; CF/Caucasian (Cc) clover; CF/subterranean (Sub) clover or lucerne. Water extraction measurements showed soils for all dryland pastures had a similar plant available water content of 280±19.8 mm. Dry matter measurements of yield, botanical composition and herbage quality were assessed from 1 July 2008 until 30 June 2009. Lucerne had the highest annual yield of 14260 kg DM/ha/y followed by the CF/Sub at 9390 kg DM/ha/y and the other grass based pastures at ≤ 6900 kg DM/ha/y. All pastures used about 670±24.4 mm/y of water for growth. Lucerne had the highest annual water use efficiency (WUE) of 21 kg DM/ha/mm/y of water used (total yield/total WU). The WUE of CF/Sub was the second highest at 15 kg DM/ha/mm/y, and the lowest was CF/Wc at 9 kg DM/ha/mm/y. The CF/Sub pastures had the highest total legume content of all grass based pastures at 21% and as a consequence had the highest annual nitrogen yield of 190 kg N/ha. This was lower than the monoculture of lucerne (470 kg N/ha). Ryegrass/white clover had the highest total weed component in all pastures of 61%. For dryland farmers spring is vital for animal production when soil temperatures are rising and moisture levels are high. The water use efficiency at this time is important to maximize pasture production. In spring lucerne produced 8730 kg DM/ha, which was the highest dry matter yield of all pastures. The CF/Sub produced the second highest yield of 6100 kg/DM/ha. When calculated against thermal time, CF/Sub grew 5.9 kg DM/ºCd compared with lucerne at 4.9 kg DM/ºCd. The higher DM yield from lucerne was from an extra 400 ºCd of growth. The highest seasonal WUE of all pastures occurred in the spring growing period. Linear regressions forced through the origin, showed lucerne (1/7/08-4/12/08) had a WUE of 30 kg DM/ha/mm (R2=0.98). Of the grass based pastures, CF/Sub produced 18 kg DM/ha/mm (R2=0.98) from 1/7 to 10/11/08 from 270 mm of water used. The lowest spring WUE was 13.5 kg DM/ha/mm by CF/Bal pastures which was comparable to the 14.3±1.42 kg DM/ha/mm WUE of CF/Wc, CF/Cc and RG/Wc pastures. During the spring, CF/Sub clover had the highest spring legume component of the grass based pastures at 42% and produced 120 kg N/ha. This was lower than the 288 kg N/ha from the monoculture of lucerne. Sub clover was the most successful clover which persisted with the cocksfoot. Based on the results from this study dryland farmers should be encouraged to maximize the potential of lucerne on farm, use cocksfoot as the main grass species for persistence, rather than perennial ryegrass, and use subterranean clover as the main legume species in cocksfoot based pastures. By increasing the proportion of legume grown the water use efficiency of a pasture can be improved. When pastures are nitrogen deficient the use of inorganic nitrogen may also improve pasture yields particularly in spring.