This study reviews published information on the tactical management decisions needed to maximise economic grain yield in winter-dominant rainfall regions of the Mediterranean type. Tactical decisions are defined as those relating to the period from immediately before sowing to harvest. Tactical management is the principal means by which farmers respond to changing environmental and short-term economic conditions as the season progresses. The review considers published evidence that underpins these decisions and relates to cereal crops (wheat, barley and oats), pulse crops (field pea, faba bean, chickpea and narrow-leaved lupin) and canola.

The criteria used to guide management decisions during the season involve soil and tissue tests for nutrients, knowledge of weed numbers and resistance status in the current and previous seasons, weather conditions that favour disease development, and knowledge of thresholds and biology of insect pests that may warrant control measures. All of these decisions can be related to the timing of the opening rains and the length of the growing season; the crop, pasture or weeds present in the previous two seasons; the presence of pest- and disease-bearing crop residues; and the type of tillage in use. Most of these indicators require further refinement through research across environments, soil types, crop types and production systems.

The likely interactions between tactical or short-term management decisions, longer term or strategic decisions, and genetic factors are discussed. The prevalent use of chemicals in the management of biotic factors that can impact the crops is noted, as is progress towards various systems of ‘integrated’ management of these threats to crop production. Most tactical decisions in rainfed cropping systems appear to be supported by adequate evidence, although some decisions are still based on practical experience and observations.

Application of tactical management practices together with strategic management and use of improved genotypes provides the possibility of achieving rainfall-limited potential grain yield at a regional scale. The papers reviewed have been selected partly on the basis that the experimental treatments achieved the estimated potential grain yield. Where the potential grain yields are not being achieved in commercial crops, it remains unclear whether this is due to inadequate adoption of existing information or inadequate research to identify and address the underlying causes. We highlight the need to devise a simple decision aid to assist farmers and their advisers to respond to the variable seasonal conditions evident since the turn of the Century.

Septoria tritici blotch (STB), caused by Zymoseptoria tritici, is an important disease of wheat worldwide. This study was performed to investigate the efficacy of Stb genes against 10 isolates of Z. tritici and to elucidate the resistance response pattern of 185 wheat genotypes to STB. The 10 isolates showed different virulence patterns on the Stb differentials. Effectiveness determination showed that most Stb genes (particularly Stb1–Stb9) were ineffective against the 10 isolates, whereas Kavkaz-K4500 (possessing Stb10, Stb12), Arina and Riband (possessing Stb15), and M3 (possessing Stb16 and Stb17) were resistant to all isolates tested. Of the 185 wheat genotypes, 72% were susceptible to all isolates, indicating that these genotypes lacked any effective resistance genes at the seedling stage against the isolates used. The remaining 51 genotypes showed specific resistance to one or more isolates, suggesting that they contain at least one effective resistance gene. Six genotypes were resistant to all isolates, indicating that they may possess broad-spectrum resistance gene(s) or a combination of diverse uncharacterised Stb genes that could be effectively used in breeding programs.

The effects of uniformity in border rows and population structure on the yield of hybrid maize (Zea mays L.) grown at high planting density was studied in field experiments at Qitai Farm (89°34′E, 44°12′N), Xinjiang, China, during 2013 and 2014. The experiments incorporated a planting density of 12.0 plants m^–2 and three maize cultivars (M753, LY66, LD565). Border effects and uniformity in the border rows were studied at the silking and maturity stages. Yields of M753, LY66 and LD565 were 16.46, 15.02 and 11.45 Mg ha^–1, respectively. Analysis of yield components in border rows indicated that the number of kernels per ear, 1000-kernel weight and yield per plant of M753 stopped decreasing after the second row in the border, whereas those of LY66 and LD565 stopped decreasing after the third row in the border, demonstrating a stronger border effect. The cultivars intercepted >95% of the light, but light transmission was lower for M753 than for LY66 and LD565, which resulted in the highest light interception in the upper canopy layers of M753. Analysis of uniformity in the border rows showed that the uniformity values for plant height, ear height, stem diameter, number of kernels per ear, 1000-kernel weight and yield per plant were higher for M753 than for LY66 and LD565. For the three cultivars, uniformity values could be ranked in the order plant height > ear height > stem diameter. The results suggest that cultivars with weaker border effects and greater uniformity in border rows can produce higher yields when grown at a high planting density.

Weeds are a major contributing factor to crop yield loss. Weed control is regularly practiced during the growing season, with many growers making a conscious effort to minimise weed-seed return to the soil seedbank during the cropping program. However, growers may be unintentionally introducing weed seeds through sowing of contaminated crop seed. Using samples of crop seed obtained from 29 growers across two Western Australian grain-growing regions, 81 samples were hand-cleaned to determine weed-seed contamination levels. Of those samples, 41% were weed-free, and in the remaining 59%, the main contaminant was Lolium rigidum (annual ryegrass), occurring in 49% of contaminated samples. Crop type and cleaning method had significant effects on the level of weed-seed contamination, with barley having higher levels of contamination than other crops, and professional contractors providing lower contamination than other methods of cleaning. However, any seed-cleaning method provided significantly cleaner grain samples than no seed cleaning. This study established that crop-seed contamination was evident on Western Australian farms and that growers may be unintentionally sowing weed seeds with their crops. Seed cleaning combined with judicious paddock selection and weed-seed removal during the growing season can lead to weed-free crop seed.

Chickpea (Cicer arietinum L.) is a leading food legume primarily grown in marginal areas and consumed all over the world. However, its production is limited owing to zinc (Zn) deficiency in many chickpea-based cropping systems. This study was conducted over two years to evaluate the effect of Zn application through seed treatments on productivity and grain Zn biofortification of kabuli and desi chickpea types in Punjab, Pakistan. Pre-optimised doses of Zn were applied as (i) seed priming (0.001 m Zn) and (ii) seed coating (5 mg Zn kg^–1 seed), using ZnSO₄.7H₂O (33% Zn). Hydropriming (soaking in water) and non-primed dry seeds were used as control treatments. Zinc seed treatments significantly improved leghemoglobin contents, nodulation, grain yield, grain Zn yield, grain bioavailable Zn, grain minerals and grain Zn concentration compared with control treatments in both chickpea types. During both years, kabuli chickpea receiving Zn seed coating had higher grain yield (2.22 and 2.73 t ha^–1) and grain Zn yield (103 and 129 g ha^–1) than kabuli receiving other treatments. Likewise, during both study years, maximum grain bioavailable Zn (4.58 and 4.55 mg Zn day^–1) was recorded with Zn seed coating in both chickpea types. Kabuli chickpea had more grain bioavailable Zn than desi. With regard to seed treatments, desi chickpea was more responsive to Zn osmopriming, whereas kabuli was more responsive to Zn seed coating. In conclusion, Zn seed treatments, as seed priming and seed coating, are effective methods for improving the productivity, grain quality and Zn biofortification of both desi and kabuli chickpea.

Internode length and diameter in soybean (Glycine max (L.) Merr.) are closely associated with lodging. The pattern of internode elongation and increase in internode diameter and factors involved were studied in two soybean cultivars, HN48 (tall-stem cultivar) and HN60 (dwarf cultivar), in the growing seasons of 2017 and 2018. Four treatments included natural lighting, shading of the apical meristem, covering of all internodes with aluminium foil, and whole-plant shading with plastic shading nets. When the number of internodes (N) on the main stem was >3, internode N began to elongate. Internode N – 1 exhibited the most rapid elongation, and internode N – 2 elongated slowly. Internode N – 3 stopped elongating, but the increase in internode diameter did not cease as internode elongation stopped. Shading the soybean apical meristem, the stem, and the whole plant all led to internode elongation. Different shading conditions did not alter the pattern of internode elongation. Soybean stem and apical meristem were both light-sensitive tissues. With an increase in shading, internode length increased, whereas internode diameter decreased. Contents of gibberellic acid (GA₃) and salicylic acid in the stem also increased, but abscisic acid content decreased. Shading reduced the size of starch grains but increased the number of osmiophilic granules in the chloroplast. Elevated GA₃ level was the main cause of the changes in internode length and diameter induced by shading. These results suggest that reduction in GA₃ synthesis and enhancement in carbohydrates formation could a strategy for soybean plants to avoid lodging.

Both Alternaria japonica and A. brassicae cause severe Alternaria leaf spot on canola (Brassica napus) and mustard (B. juncea). We tested 103 Brassicaceae varieties including 93 Australian canola, nine Indian mustard, and a single variety of Ethiopian mustard (B. carinata) under greenhouse conditions to identify host resistance to Alternaria leaf spot caused by A. japonica and A. brassicae in terms of disease incidence (percentage leaf disease incidence, %LDI), disease severity (percentage leaf area diseased, %LAD) and defoliation (percentage leaf collapse index, %LCI). Against A. japonica, across the three parameters, B. napus Surpass 404 CL was the most resistant (%LDI 7.5, %LAD 5.0, %LCI 0). Varieties Hyola 635 CC, Oscar, AG-Outback and Rottnest, with %LDI 15.6–19.4 and %LAD 12.5–15.6, also showed strong resistance, and with %LCI 10. Varieties 47C02, ATR-Signal and Clancy of B. napus showed a moderate level of resistance across %LDI (21.2–25.6) and %LAD (15.0–20.6), along with a low level of defoliation (%LCI 10). Varieties 46C03, 46C72, ATR-Cobbler and Granite TT of B. napus also showed a moderate level of resistance, with %LDI 23.1–28.7, %LAD 18.1–20.6 and %LCI 11.2–14.4. The significance of this resistance against A. japonica is highlighted by the severe disease on B. napus Thunder TT (%LDI 78.8, %LAD 72.5, %LCI 47.5). Against A. brassicae, all varieties showed susceptibility; however, B. napus ATR-Grace was the least susceptible in relation to disease incidence (%LDI 41.2) and severity (%LAD 36.2), and B. napus Hyola 450 TT the most susceptible (%LDI 90.0, %LAD 82.5). Variety Hurricane of B. napus was the least susceptible in terms of consequent defoliation (%LCI 11.2) and B. napus CBTM Tribune the most susceptible (%LCI 81.2). The B. carinata variety BCA 1 (ATC 95065) and all test B. juncea varieties showed susceptibility to both pathogens. These findings demonstrate high levels of resistance across Australian canola varieties against A. japonica that can be directly deployed where A. japonica is important and can be utilised by breeders for improving resistance in future varieties. By contrast, susceptibility across Australian canola and mustard varieties to A. brassicae is concerning, highlighting a need to locate suitable resistances and, until effective host resistance can be located, to develop and deploy cultural and chemical options.

Low phosphorus (P) constrains productivity of many of the permanent pastures of south-eastern Australia where wool and meat production are important. Whereas the need for fertilisation with P is indisputable for many soils, the benefits of liming to ameliorate soil acidification are not always clear in terms of forage production or quality. This experiment, by measuring botanical composition and groundcover over 10 years, aimed to address the issue of forage composition and groundcover. Merino wethers were continuously grazed on a permanent pasture under two stocking rates (low and high) following treatments with three rates of surface-applied lime and two rates of P. The lime rates were: nil, and sufficient to raise the pH_CaCl2 of the 0–10 cm soil layer to 5.0 and to 5.5. Phosphorus was added as two rates of single superphosphate: 125 kg ha^–1 every 2–3 years, and 250 kg ha^–1 every year. Two hypotheses were proposed: (i) as lime application rate increased, it would lead to the pasture swards having a higher percentage of species favourable for grazing animal production, and a higher level of sward groundcover would be maintained; and (ii) legume presence would be favoured by a higher level of applied P over the long term. The Millennium Drought (1997–2008), which coincided with this experiment (1998–2008), tended to mask or reduce lime effects; nevertheless, the higher legume content in the sward, as well as the superior groundcover found in the high lime–high P treatments at various times throughout the experiment and at its completion compared with the nil-lime control, indicated positive forage effects of lime application. Moreover, by the termination of the experiment in 2008, groundcover generally tended to be lower under nil lime than in treatments that had received lime. The higher proportion of legume in the sward was closely linked to greater applied P, although this did not occur at the low stocking rate in the absence of lime. By contrast, similar high P–low stocking rate treatments but with applied lime had the highest clover contents. It is proposed that the poor persistence of the treatment without lime may be due to a combination of poor legume seedset, because of excessive competition from accompanying grasses, and aluminium toxicity adversely affecting legume growth.