Crop and Pasture Science Crop and Pasture Science Society
Plant sciences, sustainable farming systems and food quality
Crop and Pasture Science

Crop and Pasture Science

Volume 66 Number 2 2015

CP14063Potential legume alternatives to fallow and wheat monoculture for Mediterranean environments

Scott Christiansen, John Ryan, Murari Singh, Serkan Ates, Faik Bahhady, Khalil Mohamed, Omran Youssef and Stephen Loss
pp. 113-121

In a two-course rotation experiment in north-eastern Syria over 10 seasons, the highest wheat grain yields were following fallow (2.57 t ha–1), followed by medic, vetch or lentil (1.90–2.22 t ha–1), and continuous wheat (1.14 t ha–1). The wheat–vetch and wheat–lentil rotations were at least twice as profitable as wheat–fallow, and three times continuous wheat. The inclusion of grain legumes is an excellent alternative to wheat–fallow and continuous wheat production.

Jandaroi, an Australian durum wheat variety, exhibited severe non-pathogenic leaf-spotting in some commercial northwest NSW crops. Leaf-spotting symptoms were reproduced in a glasshouse experiment of durum wheat varieties grown in nil-chloride nutrient solutions. Field experiments showed no significant yield response to chloride fertiliser, probably because plants accessed chloride deep in the soil profile. A strong varietal response to leaf-spotting at low soil chloride concentration demonstrated good potential for breeding to reduce the potential impact of chloride deficiency

Potassium (K) deficiency is becoming increasingly common because the input of K through fertilisers is less than the removal of K at harvest. Two-year field experiments showed that applying K on low K soils enhanced wheat and barley growth and grain yield under drought and salinity. There was also partial K substitution by sodium (Na) in barley on moderately saline soils, which may need taking into account for K-fertiliser management.

The combine stress of salinity and high temperature significantly reduced emergence percentage, seedling growth, fresh and dry seedling weight, and chlorophyll content. Malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were increased due to both environmental factors. All hormone treatments positively improved most of the morphological and physiological measurements under salinity and temperature stress, but salicylic acid (SA) was more effective than the other hormone treatments.

Root growth of cotton, maize and sorghum was evaluated using a combination of core sampling, and minirhizotrons and an image capture system. Rooting depth of cotton was shallow. Subsoil (0.6–0.9 m) root growth of cotton was sparse under continuous cotton but was greater with a cotton–wheat rotation. Surface root length density of a Bollgard® cotton variety was less than that of its non-Bollgard counterpart. Subsoil root growth of sorghum and maize ranged from moderate to high.

Chicory and plantain cultivars used for dairying were managed under different defoliation regimes for 18 months. Chicory leaf production was maximised in swards defoliated at 250 mm extended leaf height. With plantain, longer defoliation intervals  increased both leaf and stem yield, and reduced nutritive value. Defoliating plantain swards at 250 mm extended leaf height appeared to provide a balance between yield and nutritive value. Residual height had less of an effect on yield and nutritive characteristics than defoliation interval.

Setaria pumila and Digitaria sanguinalis are undesirable, C4 annual grasses with a lower nutritive value than that of Lolium perenne. Setaria pumila was defoliated to a greater extent than D. sanguinalis. In addition, post-grazing cover and post-grazing height for both annual grasses increased over the grazing season and were associated with declining nutritive value of both species. Both species readily produced new panicles between grazings and are likely to spread in L. perenne-based dairy pastures unless interventions are used.

CP14164Effects of lucerne genotype on morphology, biomass production and nitrogen content of lucerne and tall fescue in mixed pastures

Amel Maamouri, Gaëtan Louarn, François Gastal, Vincent Béguier and Bernadette Julier
pp. 192-204

Legume–grass mixtures ensure a high, protein-rich forage yield without nitrogen fertilization. In an experiment that included 46 lucerne and two tall fescue genotypes tested in microplots, we analyzed how lucerne genetic variation affects agronomic traits. Both tall fescue genotypes grown with highly productive lucerne genotypes had an increased leaf elongation and N status but a reduced tiller number, which could limit their persistence.

CP14162The economic significance of maintaining pasture production at its peak value

C. I. Ludemann, J. L. Jacobs and K. F. Smith
pp. 205-213

Persistence is an important, but generally poorly defined trait of perennial pasture plants. Increases of up to AU$202 ha–1 year–1 in operating profit from pasture persistence—defined as a 1-year increase in duration of peak dry matter production of perennial ryegrass—were modelled for two temperate dairy farms of Australia, compared with up to a $21 ha–1 year–1 increase in operating profit for pasture persistence defined as a reduction in rate of decline in annual pasture production. Results of this study could be used by farmers and plant breeders to aid their decision-making to allocate resources towards improving pasture persistence.

2,4-ditert-butylphenol caused excessive production of reactive oxygen. This leads to enhanced lipid peroxidation levels and membrane damage. Increased levels of scavenging enzymes indicate their induction as a secondary defense mechanism in response to 2,4-ditert-butylphenol.

The impact of deficit irrigation on processing tomato at two plant densities was examined in a 2-year experiment. At 5 plants m–2 dry biomass and fruit yield per plant were reduced but fruit yield per unit area was greater than that at 2.5 plants m–2. Deficit irrigation enhanced WUE and allowed a water saving of >45%. A yield response factor Ky greater than Kss reveals a greater crop sensitivity to soil-water deficit in terms of fruit yield than dry biomass.

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