Intercropping is a farming practice that fights pests and diseases and improves plant growth. The use of plant growth-promoting rhizobacteria (PGPR) strains to boost the yield of intercrops constitutes a promising tool in agricultural practice. This study investigated the impact of single inoculation and co-inoculation with PGPR on plant biomass and phosphorus (P) and nitrogen (N) concentrations under different cropping systems. Two PGPR strains with different traits were selected: PGP13 (Rahnella aquatilis) and PS11 (Pseudomonas sp.). A greenhouse experiment was designed using durum wheat (Triticum durum L.) and faba bean (Vicia faba L.), sole cropped or intercropped, including four inoculation treatments: (i) uninoculated, (ii) inoculated with PS11 (iii) inoculated with PGP13, and (iv) co-inoculated with PS11 + PGP13. Co-inoculation under the intercropping system improved plant dry matter and enhanced bean pod and wheat spike weights to 685.83% and 385.83%, respectively, of the values for uninoculated, intercropped plants. Higher P and N concentrations were detected in intercropped, co-inoculated plants and in bean pods and wheat spikes. The results were then submitted to principal component analysis, showing that treatments with higher biomass and nutrient concentrations were strongly correlated with intercropped, co-inoculated plants.

Architecture-efficient sorghum (Sorghum bicolor (L.) Moench) has erect leaves forming a compact canopy that enables highly effective utilisation of solar radiation; it is suitable for high-density planting, resulting in an elevated overall production. Development of sorghum ideotypes with optimal plant architecture requires knowledge of the genetic basis of plant architectural traits. The present study investigated seven production-related architectural traits by using 181 sorghum recombinant inbred lines (RILs) with contrasting architectural phenotypes developed from the cross Shihong 137 × L-Tian. Parents along with RILs were phenotyped for plant architectural traits for two consecutive years (2012, 2013) at two locations in the field. Analysis of variance revealed significant (P ≤ 0.05) differences among RILs for architectural traits. All traits showed medium to high broad-sense heritability estimates (0.43–0.94) and significant (P ≤ 0.05) genotype × environment effects. We employed 181 simple sequence repeat markers to identify quantitative trait loci (QTLs) and the effects of QTL × environment interaction based on the inclusive composite interval mapping algorithm. In total, 53 robust QTLs (log of odds ≥4.68) were detected for these seven traits and explained 2.11–12.11% of phenotypic variation. These QTLs had small effects of QTL × environment interaction and yet significant epistatic effects, indicating that they could stably express across environments but influence phenotypes through strong interaction with non-allelic loci. The QTLs and linked markers need to be verified through function and candidate-gene analyses. The new knowledge of the genetic regulation of architectural traits in the present study will provide a theoretical basis for the genetic improvement of architectural traits in sorghum.

Oxalate may cause hypocalcaemia or formation of urinary calculi in animals with prolonged grazing of Napier grass (Pennisetum purpureum) × pearl millet (bajra, P. glaucum) hybrid (NBH). We investigated the influence of nitrate metabolism, nitrogen (N) nutrition, N forms and seasonal variation on oxalate accumulation in leaves of NBH in a field experiment in Ludhiana, India. The experiment was a randomised block design with three N sources (nitrate, amide and ammonium), three application rates (50, 75 and 100 kg N/ha), four seasons (summer, monsoon, autumn, pre-winter) and three replicates. Applied N nutrition induced oxalate synthesis and activities of nitrate reductase (NR) and nitrite reductase (NiR) enzymes. A positive association of N nutrition with both oxalate accumulation and nitrate-reducing enzymes was found. Nitrate-N increased oxalate accumulation and NiR activity more than ammonium and amide. A differential effect of seasons on NR and NiR activities, as well as on oxalate accumulation, was observed. Among different harvest seasons, NR and NiR activities were positively associated with oxalate accumulation in summer and the monsoon season. These results suggest that N fertilisation, particularly in nitrate form, is associated with upregulation of nitrate-reducing enzymes, leading to oxalate accumulation in NBH leaves.

In Australia, efforts are under way to revive the pigeonpea (Cajanus cajan (L.) Millsp.) industry, which has high export potential because of an increased demand in the international market. However, weeds are a major constraint to achieve high yield in pigeonpea. This study was designed to assess the effect of row arrangement and herbicide treatment on weed suppression and pigeonpea grain yield. Row arrangements included row spacing (narrow, 25 cm; wide, 50 cm) and paired rows (rows 25 cm apart within a pair, each pair separated from the next by 75 cm). Herbicide treatments were: untreated control; pre-emergent pendimethalin at 910 g a.i. ha^–1; post-emergent imazapic at 84 g a.i. ha^–1; and pre-emergent pendimethalin followed by post-emergent imazapic (rates as above). In the first year, Trianthema portulacastrum was the dominant weed, and infestation was 100% in the non-treated control plots. In the second year, other weeds (Setaria viridis, Eragrostis cilianensis and Chloris virgata) comprised 30% of the weed population. Averaged over row arrangements, grain yield varied from 2088 to 2689 kg ha^–1 in 2017 and from 835 to 2145 kg ha^–1 in 2018, and was lowest in the untreated control and highest in the plots treated with the sequential application of pendimethalin and imazapic. Averaged over years and herbicide treatments, yield was lower in paired rows (1850 kg ha^–1) than in narrow (2225 kg ha^–1) and wide (2165 kg ha^–1) row spacings. In the first year, all herbicide treatments provided >50% control of T. portulacastrum in the narrow and wide row spacings and increased yield by >22% over the untreated control. In the second year, the single application of imazapic proved inferior for controlling weeds, resulting in a 21% reduction in grain yield compared with sequential application of pendimethalin and imazapic. In both years, grain yield was similar for the single application of pendimethalin and sequential application of pendimethalin and imazapic. Despite the complex weed flora in 2018, the single application of imazapic provided acceptable weed control only when the crop was planted at 25 cm row spacing. Our results suggest that the single application of pendimethalin was effective on T. portulacastrum. However, in a complex weed flora situation, the sequential application of pendimethalin and imazapic provided effective weed control and resulted in improved yield.

Seed shape (SS) of soybean (Glycine max (L.) Merr.) is an important morphological trait that significantly affects the quality of marketable seed. Study of the genetic architecture of SS is important and basic to soybean molecular breeding. In the present study, a natural soybean population of 202 diverse accessions mainly from China was used to analyse the genetic basis of SS via genome-wide association analysis (GWAS), which was based on single-nucleotide polymorphisms (SNP) generated by specific-locus amplified fragment sequencing method. In total, 27 335 SNPs were finally identified with minor allele frequencies >5%. By using GWAS, 14 quantitative trait nucleotides (QTNs) were identified to be associated with seed length, 13 with seed width and 21 with seed thickness in four tested environments. Among these QTNs, 21 QTNs overlapped or were located in the linked genomic regions of the reported quantitative trait loci related to SS or seed weight; and the other 27 QTNs were novel loci for SS. Ten QTNs showed environmental stability and were detected under at least two environments. In total, 83 genes were predicted in the 200-kbp flanking region of six stable QTNs that could be detected under >three environments. Gene-based association analysis was performed by using 38 accessions of diverse SS; 778 SNPs were found in the 83 genes based on 38 accessions, and 270 SNPs from 41 genes were found significantly associated with SS. Twenty-eight genes were environmentally stable and/or pleiotropic in controlling two or more SS-related traits at the same time. The identified loci along with the candidate genes could be of great value for studying the molecular mechanisms underlying SS and improving the potential seed yield of soybean.

Climate change is a global phenomenon that presents diverse threats to global food security. Of the avocados (Persea americana Mill), Hass is the most commonly cultivated variety in the world, representing an important source of nutrition in numerous countries, yet its potential risks in the face of climate change are unknown. Here, we characterise current and future potential distributional areas for Hass avocado under different scenarios of climate change across the Americas. We use ecological-niche modelling approaches to explore implications of changes in climate, considering 22 general circulation models, two emissions scenarios, and six model parameterisations. The current potential distribution of Hass avocado extends across tropical America (excluding most of Amazonia), including some areas at higher latitudes. Future projections show stability in potential distribution. Range expansions are expected mainly in temperate areas, and range contractions are related to temperature and precipitation increases, mostly in Amazonia. Model parametrisations contributed the most to overall variation in future projections, followed by climate models, and then emissions scenarios. Our conclusion of relative stability for the crop’s potential distribution is still subject to effects on other components of avocado production systems, and may be vulnerable to extreme phenomena.

Wild lettuce (Lactuca serriola L.) is a significant emerging agricultural and environmental weed in many countries. This invasive species is now naturalised in Australia and is claimed to cause significant losses within the agricultural industry. Sustainable management of wild lettuce has been hampered by a lack of detailed knowledge of its seed ecology. Laboratory-based studies were performed to examine the potential influence of environmental factors including temperature and light conditions, salinity, pH, moisture availability and burial depth on the germination and emergence of two spatially distant populations of wild lettuce. Results suggested that the germination of wild lettuce seeds occurred across a broad range of temperature conditions (12-h cycle: 30°C/20°C, 25°C/15°C and 17°C/7°C) for both populations. We also found that these seeds are non-photoblastic; germination was not affected by darkness, with >80% germination in darkness for both populations at all tested temperature ranges. Germination significantly declined as salinity and osmotic stress increased for both populations, with seeds from the Tempy population were more affected by NaCl >100 mM than seeds from Werribee, but in neither population was there any observed effect of pH on germination (>80% germination in both populations at all tested pH ranges). For both populations, germination significantly decreased as burial depth increased; however, the two populations differed with regard to response to burial depth treatment, whereby seeds from the Tempy population had higher emergence than those from Werribee at 0.5 cm burial depth. These results suggest that light-reducing management techniques such as mulching or use of crop residues will be unsuccessful for preventing germination of wild lettuce. By contrast, burial of seeds at a depth of at least 4 cm will significantly reduce their emergence.

Pastures are the most practical and cost-effective way to feed cattle and are the basis of livestock production in Central Brazil. Grass–legume intercropping is essential for increasing production in sustainable animal-feeding systems. The aim of the present study was to evaluate the productive and nutritional characteristics of Brachiaria brizantha (A.Rich.) Stapf (palisade grass) cultivars intercropped with Stylosanthes cv. Campo Grande (multiline 80% S. capitata and 20% S. macrocephala) in different forage systems, in different seasons of the year, over a 2-year period. A randomised block experimental design was used, with three replicates. The treatments consisted of the following seven forage systems: Piata palisade grass, Paiaguas palisade grass, Stylosanthes cv. Campo Grande, row intercropping of Piata palisade grass and Stylosanthes, mixed intercropping of Piata palisade grass and Stylosanthes, row intercropping of Paiaguas palisade grass and Stylosanthes, and mixed intercropping of Paiaguas palisade grass and Stylosanthes. Evaluations were performed in each season of the year (winter, spring, summer, autumn) on the same plots over the 2-year period. Piata and Paiaguas palisade grass behaved similarly in all forage systems, indicating that both can be intercropped with Stylosanthes. Grass–legume intercropping had a positive effect on the productive and nutritional characteristics of the forage plants, increasing dry matter production, crude protein concentrations and in vitro dry matter digestibility, and decreasing the fibre fractions. Row intercropping was more efficient at maintaining high proportions of legume plants in the system, resulting in greater forage production and quality.