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The Australian tomato Solanum orbiculatum ssp. orbiculatum is an edible bush tomato endemic to the more arid areas of Western Australia, South Australia, and the Northern Territory. Breeding system data indicate that the plants are potentially self-compatible but are unable to carry out spontaneous autogamy or agamospermy. The flower is protogynous, as the stigma become receptive to pollen germination while still in bud condition and the anthers do not release pollen immediately after anthesis. This arrangement is a simple and common way to avoid too much self-pollination, favours cross pollination, and would allow forced bud pollination for hybrid development. The floral structure and morphology of this species can also encourage cross pollination, as the stigma is mostly exserted above the anther's tips. In an attempt to examine the hypothesis of a positive correlation between pollen grain size and style length, we found a statistically significant difference between the pollen size of the long-styled and short-styled flowers. Pollen in vitro germination and viability tests have been optimised to facilitate effective breeding work on this species. A modified Brewbake and Kwack (BK) medium supplemented with 20% sucrose and 2.5% PEG 4000 has been found to be the most efficient media components for the in vitro germination of viable pollen grains. Alternatively, Alexander's and acetocarmine (1%) stains have shown the highest positive correlation with the in vitro pollen germination test and, therefore, can be used as quick tests for checking pollen viability. Moreover, pollen grains stored for three months under 4 °C and dry conditions can be used efficiently to effect fertilisation in breeding programs, as it can maintain more than 50% of the original viability. This study will contribute to understanding the evolution and systematic relationships of species and for founding effective conservation programs. Furthermore, understanding the reproductive biology of this species is also of interest because of its potential for tomato breeding. [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity imposes a significant limitation to crop production in South Western Australia. This paper examines the impact of surface-applied lime and gypsum on soil solution chemistry in the short term (1 year) and the long-term (10 years) in water limited environments. In the experiments, we measured soil solution chemistry using a paste extract on soil profile samples collected to a depth of 50 cm. We then used the chemical equilibrium model MINTEQ to predict the presence and relative concentrations of Al species that are toxic to root growth (Al associated with Al3+ and AlOH2 or Toxic-Al) and less non-toxic forms of Al bound with sulfate, other hydroxide species and organic matter. A feature of the soils used in the experiment is that they have a low capacity to adsorb sulfate. In the short term, despite the low amount of rainfall (279 mm), sulfate derived from the surface gypsum application is rapidly leached into the soil profile. There was no self-liming effect, as evidenced by there being no change in soil solution pH. The application of gypsum, in the short term, increased soil solution ionic strength by 524–681% in the 0–10 cm soil layer declining to 75–109% in the 30–40 cm soil layer due to an increase in soil solution sulfate and calcium concentrations. Calcium from the gypsum application displaces Al from the exchange sites to increase soil solution Al activity in the gypsum treatments by 155–233% in the short term and by 70–196% in the long term to a depth of 40 cm. However, there was no effect on Toxic-Al due to Al sulfate precipitation. In the long term, sulfate leaching from the soil profile results in a decline in soil solution ionic strength. Application of lime results in leaching of alkalinity into the soil profile leading to a decreased Toxic-Al to a depth of 30 cm in the long term, but it did not affect Toxic-Al in the short term. Combining an application of lime with gypsum had the same impact on soil solution properties as gypsum alone in the short term and as lime alone in the long term. [ABSTRACT FROM AUTHOR]

Tedera is a forage legume that can provide out-of-season green feed in Mediterranean climates. To date, growers have had no comprehensive soil nutrition guidelines to optimise tedera production. We undertook field and glasshouse studies to understand tedera's macronutrient requirements. Three field experiments were sown with tedera cv. Lanza® at Cunderdin, Dandaragan and Three Springs in Western Australia. These experiments evaluated seven levels of phosphorus (P) (0–30 kg ha−1) and potassium (K) (0–80 kg ha−1) and two combined treatments with P and K. Glasshouse pot experiments were conducted using tedera cultivars Lanza® and Palma and lucerne cultivar SARDI Grazer. Ten concentrations of added P (0–256 mg kg−1), ten of K (0–256 mg kg−1) and ten of sulphur (S) (0–16 mg kg−1) were tested. There was no significant response to P or K in field soils at Cunderdin or Three Springs. There was no response to K at Dandaragan, but P produced a positive response in the July and October growing season cuts. In the glasshouse, tedera cultivars reached peak productivity at lower soil Colwell P (7.6 to 12 mg kg−1) than lucerne (22 mg kg−1). Lanza® had a moderate biomass response, and Palma did not show a significant response to Colwell K (0.8 to 142 mg kg−1) or soil S (1.3 to 12.5 mg kg−1). Nodulation was greatly reduced at the extremes in P and K treatments. For the first time, these field and glasshouse results have allowed us to establish guidelines for optimal soil nutrition for tedera that growers can use to benchmark the soil or shoot nutrient status of their tedera pastures and assess the economic benefit of correcting deficiencies. [ABSTRACT FROM AUTHOR]

Seed germination and seedling growth are two essential early determinants of subsequent crop yield and quality. A high germination percentage of industrial hemp (Cannabis sativa L.) seed is required to import into Australia. The viability of hemp seed can decline rapidly depending on storage and other factors; hence, the quality of imported seed is not always reliable. Here, we aimed to investigate germination and early seedling growth responses of 14 industrial hemp varieties after being imported from various countries. Germination trials were conducted with 100 seeds of 14 varieties using a soil-less Petri dish assay and a compost growth medium under glasshouse conditions. We also assessed the effect of seed pre-treatments such as gibberellic acid (500 and 1000 mg·L−1), chlorine dioxide (500 and 1000 mg·L−1) and cold temperature (4 °C for 72 h) using 300 seeds of each of the three selected varieties in compost growth medium. Hemp varieties imported from China had higher germination and better seedling growth indices than those imported from Europe. All seed pre-treatments were associated with a decreasing trend in germination, but a positive effect on early growth responses was observed. Our findings indicate that the hemp variety Han FNQ performed better than many other varieties did regarding seed germination and seedling growth. Hemp seeds sanitising with 500 mg·L−1 of chlorine dioxide might improve the germination and early growth of seedlings. [ABSTRACT FROM AUTHOR]

Modern agricultural farming systems acidify the soil profile due to application of fertilisers with acidifying properties. In most parts of Australia, lime has been used to improve agricultural soil conditions and restore its productive potential. The observed response of crop yield to applied lime often varies with soil type, acidity profile and seasonal conditions, so it is difficult to specify the expected yield response in a given situation. We conducted a meta-analysis of 86 agricultural field trials from Western Australia (WA), New South Wales (NSW) and Victoria (VIC) where various rates of lime had been applied to the soil surface and crop yield (wheat, barley, canola, lupin or field pea) measured for a number of years after the initial application. Information from the meta-analysis was then paired with output from a crop simulation model, where the water-limited yield potential was estimated for both a neutral and acidified soil profile. The average increase in yield to applied lime across all locations and crops was 12%, but the response ranged from 0 to 185%. A trend was observed, where sites with topsoil pH (CaCl2) < 5 and subsoil pH < 4.5 had the greater benefit to liming. Soil type had little effect on the percentage yield increase. Overall, responses to applied lime were most likely when the yield of the trial site was at 50% of water-limited yield potential (or less), the quantity of lime applied was greater than 2.5 t ha−1 and the time since lime had been applied was greater than three years (with the maximum response occurring from four and sometimes up to eight years after liming). Therefore, soil pH measurements, combined with an assessment of actual yield relative to potential yield, provide the best guide to the response to surface applied lime and this response is likely to take more than four years to be realised. [ABSTRACT FROM AUTHOR]

Deep sands on the south coast sandplain of Western Australia (WA) have multiple soil constraints including water repellence, high soil strength, low nutrient levels and subsoil acidity. The aim of the study was to test contrasting methods of managing water repellence and to assess their impacts on one or more soil constraints to crop production. These methods included seeding tyne design (knife point, winged points, paired row), soil wetting agent addition, strategic inversion tillage (rotary spading, mouldboard ploughing to 0.35 m) and clay-rich subsoil addition (170 t ha−1 with incorporation by spading to 0.20 or 0.35 m). Limesand (2 t ha−1) was applied as a split plot treatment prior to tillage. Cumulative crop yields were increased by 2.1–2.6 t ha−1 over five years by the strategic deep tillage and clay application treatments compared to the control. Water repellence was reduced by the inversion ploughing and subsoil clay addition treatments only. The effect of water repellence on crop establishment was expressed only in low rainfall years (Decile < 4) and mitigated by the paired row, wetting agent, spader and clay-amended treatments. In all years, plant numbers were adequate to achieve yield potential regardless of treatment. Soil K and plant tissue K and B were increased where clay had been applied. Inversion tillage reduced soil pH, organic carbon (OC) and macro nutrients in the 0–0.1 m layer although in most years there was no significant decline in plant tissue macro nutrient levels. Soil strength was reduced as a result of the inversion tillage to a depth of 0.35 m. However, the alleviation of soil strength and the crop yield responses diminished with time due to re-compaction. No crop response to the applied lime was found over five years at this site since the soil pHCaCl2 exceeded 4.7 within the root zone. In terms of soil constraints, we conclude that compaction was the dominant constraint at this site followed by water repellence and K deficiency. [ABSTRACT FROM AUTHOR]

Triticale (X Triticosecale Wittmack) is a cereal feed grain grown annually worldwide on 4.2 million ha. Washington is the leading state for rainfed (i.e., non-irrigated) triticale production in the USA. A 9-year dryland cropping systems project was conducted from 2011 to 2019 near Ritzville, WA to compare winter triticale (WT) with winter wheat (Triticum aestivum L.) (WW) grown in (i) a 3-year rotation of WT-spring wheat (SW) -no-till summer fallow (NTF) (ii) a 3-year rotation of WW-SW-undercutter tillage summer fallow (UTF) and (iii) a 2-year WW-UTF rotation, We measured grain yield, grain yield components, straw production, soil water dynamics, and effect on the subsequent SW wheat crop (in the two 3-year rotations). Enterprise budgets were constructed to evaluate the production costs and profitability. Grain yields averaged over the years were 5816, 5087, and 4689 kg/ha for WT, 3-year WW, and 2-year WW, respectively (p < 0.001). Winter triticale used slightly less water than WW (p = 0.019). Contrary to numerous reports in the literature, WT never produced more straw dry biomass than WW. Winter wheat produced many more stems than WT (p < 0.001), but this was compensated by individual stem weight of WT being 60% heavier than that of WW (p < 0.001). Spring wheat yield averaged 2451 vs. 2322 kg/ha after WT and WW, respectively (p = 0.022). The market price for triticale grain was always lower than that for wheat. Winter triticale produced an average of 14 and 24% more grain than 3-year and 2-year WW, respectively, provided foliar fungal disease control, risk reduction, and other rotation benefits, but was not economically competitive with WW. A 15–21% increase in WT price or grain yield would be necessary for the WT rotation to be as profitable as the 3-year and 2-year WW rotations, respectively. [ABSTRACT FROM AUTHOR]

On-farm experimentation (OFE) is a farmer-centric process that can enhance the adoption of digital agriculture technologies and improve farm profitability and sustainability. Farmers work with consultants or researchers to design and implement experiments using their own machinery to test management practices at the field or farm scale. Analysis of data from OFE is challenging because of the large spatial variation influenced by spatial autocorrelation that is not due to the treatment being tested and is often much larger than treatment effects. In addition, the relationship between treatment and yield response may also vary spatially. We investigate the use of geographically weighted regression (GWR) for analysis of data from large on-farm experiments. GWR estimates local regressions, where data are weighted by distance from the site using a distance-decay kernel. It is a simple approach that can be easily explained to farmers and their agronomic advisors. We use simulated data to test the ability of GWR to separate yield variation due to treatment from any underlying spatial variation in yield that is not due to treatment; show that GWR kernel bandwidth can be based on experimental design to accurately separate the underlying spatial variability from treatment effects; and demonstrate a step-wise model selection approach to determine when the response to treatment is global across the experiment or locally varying. We demonstrate our recommended approach on two large-scale experiments conducted on farms in Western Australia to investigate grain yield response to potassium fertiliser. We discuss the implications of our results for routine practical application to OFE and conclude that GWR has potential for wide application in a semi-automated manner to analyse OFE data, improve farm decision-making, and enhance the adoption of digital technologies. [ABSTRACT FROM AUTHOR]

Surface (0–10 cm) and subsoil (soil layers below 10 cm) acidity and resulting aluminum (Al) toxicity reduce crop grain yields. In South Western Australia (SWA), these constraints affect 14.2 million hectares or 53% of the agricultural area. Both lime (L, CaCO3) and gypsum (G, CaSO4) application can decrease the toxic effect of Al, leading to an increase in crop grain yields. Within the region, it is unclear if G alone or the combined use of L and G has a role in alleviating soil acidity in SWA, due to low sulfate S (SO4–S) sorption properties of the soil. We present results from three experiments located in the eastern wheatbelt of SWA, which examined the short-term (ST, 2 growing seasons), medium-term (MT, 3 growing seasons), and long-term (LT, 7 growing seasons over 10 years) effects of L and G on grain yield and plant nutrient concentrations. Despite the rapid leaching of SO4–S and no self-liming impact, it was profitable to apply G, due to the significant ST grain yield responses. The grain yield response to G developed even following relatively dry years, but declined over time due to SO4–S leaching. At the LT experimental site had received no previous L application, whereas, at the ST and MT sites, L had been applied by the grower over the previous 5–10 years. For the LT site, the most profitable treatment for wheat (Triticum aestivum L.) grain yield, was the combined application of 4 t L ha−1 with 2 t G ha−1. At this site, the 0–10 cm soil pHCaCl2 was 4.6, and AlCaCl2 was greater than 2.5 mg kg−1 in the 10–30 cm soil layer. In contrast, at the ST and MT sites, the pHCaCl2 of 0–10 cm soil layer was ≥5.5; it was only profitable to apply G to the MT site where the soil compaction constraint had been removed by deep ripping. The use of L increases soil pHCaCl2, resulting in the improved availability of anions, phosphorus (P) in the LT and molybdenum (Mo) at all sampling times, but reduced availability of cations zinc (Zn) in the LT and manganese (Mn) at all sampling. The application of G reduced Mo concentrations, due to the high SO4–S content of the soil. [ABSTRACT FROM AUTHOR]