The role of indeterminate growth, rooting depth and maturity time in establishing a legume seedbank under drought conditions

Belinda Hackney1, 3, Simon Flinn1, 3, Jeff McCormick2, 3, John Piltz1, 3, Susan Orgill1, 3

1 NSW Department of Primary Industries, PMB, Pine Gully Rd, Wagga Wagga, NSW 2650

2 School of Agriculture and Wine Sciences, Charles Sturt University, Wagga Wagga, NSW 2650

3 Graham Centre for Agricultural Innovation, Charles Sturt University and NSW Department of Primary Industries, Pugsley Place, Wagga Wagga, NSW, 2650

Abstract

Drought can be catastrophic to pasture establishment resulting in establishment failure and financial loss.  A range of annual legumes with varying characteristics (capacity for extended periods of indeterminate growth, varying rooting depth and differing maturity times) were sown in a replicated trial near Kikoira in central NSW where growing season rainfall was only 44% of the long term average. Biserrula, an indeterminate, deep-rooted legume produced more than 170 kg seed/ha with one-third produced prior to the end of October.  French serradella, another indeterminate, deep-rooted species but of later maturity in our study produced more than 85 kg seed/ha. The early maturing gland clover was the most successful of the shallow-rooted species in producing seed, although its seed yield was significantly less than either biserrula or French serradella. Subterranean clover failed to produce seed and annual medics produced less than 10 kg seed/ha. Trifolium diffusum, a little-known species, produced 120 kg seed/ha and requires further assessment of potential. Overall, species with capacity for extended periods of indeterminate growth, deep root systems and/or early maturity were the most successful in establishing a seed bank under severe drought conditions.

Between genotype variation of lucerne (Medicago spp.) in grazing preference by sheep

Meredith Mitchell1, Kym Butler2, Lysandra Slocombe2, Steve Clark2, Viv Burnett1, Reto Zollinger2, Greg Seymour1, Zhongnan Nie2

1Agriculture Victoria, Department of Jobs, Precincts and Regions, 124 Chiltern Valley Road, Rutherglen, Victoria, 3685, www.djpr.vic.gov.au, meredith.mitchell@ecodev.vic.gov.au

2Agriculture Victoria, Department of Jobs, Precincts and Regions, 915 Mount Napier Road, Hamilton, Victoria, 3300

Abstract:

Lucerne (Medicago sativa L.) is a highly desirable forage species in temperate regions of the world.  With the many lucerne cultivars currently available and/or emerging onto the Australian market, producers may find it difficult to determine which cultivar(s) will best suit their needs.  An understanding of how these cultivars are selected and grazed by sheep may be useful for producers to make management decisions.  It was hypothesised that there will be substantial differences in sheep grazing preference among diverse cultivars. Grazing preference was evaluated on forty-seven entries (commercial cultivars and pre-release lines) at Hamilton, Victoria, in summer, winter and spring of 2017. The plots were rated using a seven-point scoring system (1 = not grazed to 7 = completely grazed) over a 27 h grazing period. The average grazing scores indicated that, with minor qualifications, all lucerne entries evaluated in this study were palatable to sheep.

Shoot and perennial organ yields of lucerne genotypes of three fall dormancy levels over five years

Sarah Maria Hoppen1, Hung Ta2, Xiumei Yang2, José Jáuregui2, Marcela Abbado Neres3, Derrick Moot2

1Lincoln University, Lincoln, Canterbury, New Zealand, 7647 e-mail: sarah.hoppen@hotmail.com

2Lincoln University, Lincoln, Canterbury, New Zealand, 7647.

3West of Parana State University, Marechal Candido Rondon, Parana, Brazil, 85930-000.

Abstract

This study evaluated productivity and persistence of a dormant (FD2), semi-dormant (FD5) and non-dormant (10) lucerne genotype over five years. The experiment at Iversen Field, Lincoln University, Canterbury, New Zealand, was sown on 4th October, 2014. Measurements of shoot, perennial organ (roots + crown) and weed yields were made from destructive samples of shoots and roots (30 cm of depth) harvested each 42 days from spring to autumn of 2015, 2016, 2017, 2018 and 2019. During the establishment phase, the FD10 had the greatest shoot yield, followed by the FD5 (9.5 and 6.3 t DM ha-1, respectively). The lucerne shoot yield increased from year 1 to year 2, with no difference until year 5, when FD10 showed a decrease of more than 2 t DM ha-1 compared with the same season in year 4. There was no difference in perennial organs in the early stages of the experiment with a maximum of 8.9 t DM ha-1 for FD5 in March of 2017. In year 5 FD10 had the lowest accumulated shoot and perennial organ yields. A reduction in FD10 canopy cover allowed an infestation of weeds (white clover, Californian thistles, dandelion and docks). The FD2 genotype had the highest yield below ground, while FD5 was the most productive above ground. The use of more fall dormant cultivars is recommended if persistence of the pastures is an important management factor.

Modelling Phenological Development of Regrowth Lucerne (Medicago sativa L.) Using APSIMX

Xiumei Yang1, Hung T. Ta1, Hamish E. Brown2, Edmar I. Teixeira2, José M. Jáuregui3, Derrick J. Moot1

1Agriculture and Life Sciences Department, Lincoln University, Canterbury, Lincoln 7647, New Zealand, PO Box 85804, http://www.lincoln.ac.nz/dryland, Derrick.Moot@lincoln.ac.nz

2 The New Zealand Institute for Plant and Food Research Ltd., Private Bag 4604, Christchurch, New Zealand

3Animal Production Department, National University of Litoral, Kreder 2805, Esperanza (3080), Santa Fe, Argentina

Abstract

Predicting lucerne phenological development is important for optimising defoliation scheduling and other management events. This study provides a simple framework to quantify the phenological response of a semi-dormant (fall dormancy 5; FD5) lucerne to environmental factors. This response was used to create algorithms for the APSIMX model, which was verified using two different fall dormancy classes (dormant FD2 and non-dormant FD10). The framework includes lucerne node appearance, height, and flowering in response to temperature and photoperiod (Pp). An evaluation of methods for calculating thermal time (Tt) indicated that the “Moot model” to define cardinal temperature most accurately computed Tt. A Tb (base temperature) of 1˚C had the lowest CV% and highest P value. In the vegetative phase, the phyllochron increased from 23 to 45˚Cd/primary leaf as Pp decreased from 16 to 12.5 h; the “heightchron” and mean Pp displayed a poor polynomial relationship (R2=0.44). In the reproductive phase, the phyllochron was consistent across Pp at 68˚Cd/primary leaf and the crop had a longer “heightchron” than in the vegetative stage. Tt to 50% bud initiation decreased as Pp increased. There was close agreement between predicted and observed values of node number and time to 50% bud initiation across genotypes.

Optimisation of perennial ryegrass, white clover and plantain mixtures for maximum dry matter yield in an intensive pasture system

Thinzar Soe Myint1, Lachlan Wood1, Alistair Black1

1 Department of Agricultural Sciences, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand,

thinzar.myint@lincolnuni.ac.nz

Abstract:

Traditional methods used to formulate pasture mixtures provide limited ability to identify the optimum mixture of constituent species. This study used a simplex design approach to identify an optimum mixture of perennial ryegrass, white clover and plantain for maximum dry matter (DM) yield in an intensive pasture system. Three monocultures and seven mixtures of the three species were chosen based on a simplex centroid design, sown at two sowing rates (1000 and 2000 seeds/m2) and grown with or without N fertiliser (275 kg N/ha) at Lincoln, New Zealand. Swards were rotationally grazed by sheep and irrigated. Yield after 14 months was not affected by sowing rate, but rather on the relative abundances of species in the pasture mix and N fertilisation. The optimal proportions of species in the seed mix for maximum yield were 0.342 perennial ryegrass, 0.254 white clover and 0.404 plantain, sown at 1000 seeds/m2 and fertilised with 275 kg N/ha. This combination produced a maximum yield of 29.9 t DM/ha. The optimal seed mix was equivalent to 8.3 kg perennial ryegrass, 3.6 kg white clover and 7.6 kg plantain (19.5 kg total seed/ha at the low sowing rate). However, perennial ryegrass and plantain became dominant in the mixtures at the expense of white clover over time, especially with N fertiliser. These changes in botanical composition meant that the optimal balance of species in the resultant pasture was 0.40 perennial ryegrass, no white clover and 0.60 plantain with 275 kg N/ha, and this combination yielded 28.7 t DM/ha.

 

Poor pasture management results in Australian horse owners using expensive daily supplementary feeding

 Claudia Macleay and Petra Buckley

School of Animal and Veterinary Science, Charles Sturt University, Wagga Wagga, NSW, 2650,

cmacleay@csu.edu.au 

Abstract:

This study investigated the feeding and management practices of Australian horse owners. Horse owners were contacted via e-newsletters, Facebook, and email to complete the online survey. Information was collected on demographics, current feeding practices, management practices and pasture condition. Quantitative analytical methods included descriptive statistics, Pearson’s chi-square test and a multivariable analysis performed in IBM SPSS. There were 4265 eligible surveys on 5464 horses used in the statistical analysis. Most horses (87%) had daily access to grazing areas, but participants reported that 59% of horses were kept in paddocks that were overgrazed, with a heavy reliance on supplementary feeding. Almost all horses (97%) were fed one or more roughages daily and 80% of horses were fed one or more commercial pellet, premix or grain concentrate daily. While only 20% of participants recorded their horses to be obese, this proportion is likely to be an underestimate, because when pasture intake estimates and reported rations were combined, the results of nutritional analysis showed that 97% of horses were receiving digestible energy above the National Research Council (NRC) (2007) recommendation and it is likely that many animals were overweight.  Australian horse owners are underestimating the nutritional content of pastures and overestimating the nutritional requirements of their horses, placing horses at risk of obesity related health problems. Australian horse owners need to recognise that well-managed pastures can provide horses with their daily nutritional requirements and this pathway is a long-term, cost-effective way of feeding horses that also reduces health and behavioural problems.

Host

The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography david_marland@hotmail.com Graham Centre for Agricultural Innovation, Charles Sturt University

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