Quality seed is a prerequisite to uniform stand establishment, which contributes to higher crop yield. However, prevalence of poor-quality cottonseed with high moisture content due to suboptimal harvesting and postharvest practices is the primary reason for crop-stand failure in developing countries. The present study evaluated the effects of harvesting environment, drying method and storage conditions on seed quality of transgenic (FH-142) and non-transgenic (FH-942) genotypes of cotton (Gossypium hirsutum L.) cultivated in Pakistan. Both genotypes were picked three times at monthly intervals during the cropping season and subjected to a ginning process. Seed was then dried in the sun or with desiccant zeolite beads, and stored for 5 months in cloth or hermetic bags at room temperature or in paper bags at 10°C. The efficiency of storage systems was evaluated by estimating moisture content and germination potential periodically in the storehouse and later under field conditions. Both genotypes exhibited better seed quality attributes at the first picking, and zeolite beads dried seed to lowest moisture content more quickly than sun-drying. Seeds of both genotypes stored hermetically retained the lowest moisture content, maximum germination potential, and lower fatty acid contents throughout the storage period, as well as performing significantly better in the field by exhibiting early and uniform stand establishment, more fruiting branches and bolls, and higher yield. Thus, use of zeolite beads in post-harvest drying followed by hermetic storage preserves cottonseed quality for longer, and leads to improved crop growth and yield of cotton. These practices will be useful for cotton farmers in developing countries.

Strategic tillage describes the occasional use of tillage in an otherwise no-till system. The practice can provide a pragmatic solution to emerging agronomic issues in no-till systems but raises concerns about prolonged or irreversible soil damage. We investigated the impact of a single tillage event at a long-term no-till experiment under treatments with retained or annually autumn-burned crop residues. One half of each residue-treatment plot received a single pass of a rotary hoe (ST) 4 weeks before sowing in 2011, the first year of the experiment; the other half of each plot remained unchanged (NT). Soil physical, chemical and biological fertility in the surface layers (0–20 cm), as well as crop growth and yield were monitored for 5 years (2011–15). Following the ST treatment, soil bulk density and strength were initially reduced to the depth of cultivation (∼15 cm) irrespective of residue treatment. Water-stable macroaggregates in the surface 0–5 cm were also reduced but recovered to pre-tillage levels within 1–2 years after ST treatment. Soil pH, total carbon (C), total nitrogen (N), and fine-fraction C and N were all initially stratified in the surface layer (0–5 cm) of the NT treatment but were redistributed more evenly throughout the 0–10 cm layer of the ST treatment and remained so throughout the 5-year period. With ST, there was an initial loss in total C stocks in the 0–10 cm layer of 2.2 t/ha, which recovered within 2 years; however, total C stocks remained lower in plots with stubble retained than with stubble burnt after 5 years. Soil Colwell P levels were not stratified and not influenced by tillage treatment, presumably because of the annual additions in the starter fertiliser at sowing. ST had no impact on crop establishment or grain yield in any year but increased the early biomass of wheat at Z30 compared with NT in the first 2 years. Annual stubble retention reduced the early growth of crops in all years, and yield of wheat in the first 3 years, consistent with long-term effects of retained stubble at the site, but there was no interaction between stubble retention and tillage treatments on soil conditions or crop growth. Crop yields of long-term, annually cultivated treatments were also similar to those of ST and NT treatments during the 5 years of the experiment. Overall, the minor short-term negative impacts on soil physical conditions, the persistent and arguably beneficial effects on soil chemistry and biology, and absence of impacts on crop production suggest that strategic tillage can be a valuable agronomic tool in sustainable production in this region.

The most important objectives of soybean (Glycine max (L.) Merr.) breeding are to increase oil content and to improve oil quality. Although the biochemical processes of oil accumulation in oilseeds are very clear, knowledge of their underlying genetic mechanisms and regulation is limited. We performed RNA-Seq of soybean seeds from six accessions with high, medium and low seed oil contents. Through comparative genome analysis, promoter-enrichment study, and protein–protein interaction (PPI) analysis, 80 lipid-metabolism-related genes and 31 transcription factors were detected. The pathways of fatty acid elongation, desaturation and export from plastid (P = 2.53E-4), and triacylglycerol biosynthesis (P = 2.31E-8), were significantly over-represented in accessions with high total oil content. Further, in an integration analysis of RNA-Seq and a genome-wide association study (GWAS) database, 62 candidate genes were found to be associated with seed oil content, 73 with oleic acid content, and 83 with linolenic acid content. Of these, 60 genes were found to be involved mainly in metabolism of lipids (25), carbohydrates (24), and amino acids (11). Thirty are known oil-synthesis-related genes; LOX1, CYP93D1 and GPT2 for oil content, SAD and FAD2 for oleic acid, and FAD2, CYP89A6 and GPT2 for linolenic acid were detected twice. There were 22 genes found to be associated with at least two oil-related traits, and of 154 pairs of PPIs, two genes for each pair of 95 PPIs (62%) were found to be associated with various oil-related traits, indicating the genetic foundations of oil-related traits. Three transcription factor genes were found to be associated with oil-related traits: HRE2 (Glyma.10G016500), ERF12 (Glyma.13G236600) and WRKY6 (Glyma.15G110300). This study provides an efficient strategy for further discovery of mechanisms of oil composition and accumulation.

Oilseed rape (Brassica napus L.) is a crucial source of edible oil and livestock feeding, and is a promising biofuel crop. The increasing demand for oilseed rape requires strategies to increase yield while retaining quality. Field experiments were performed in southern China to evaluate the impacts of fertiliser level and planting density on dry matter accumulation, seed oil and protein content (%) and yield (per ha), oil quality, and the profitability of oilseed rape. Fertiliser treatments contained nitrogen (N), phosphorus (P), potassium (K), sulfur (S) and boron (B) at four increasing rates, compared with nil fertiliser, and there were six planting densities (range 7.5–45 × 10⁴ plants ha^–1). Dry matter accumulation significantly (P < 0.05) increased in response to increasing plant population and fertiliser level, whereas harvest index decreased, suggesting that increasing the production of oilseed rape is limited to improvement of population quality. Seed oil and protein contents were significantly affected by fertiliser level rather than planting density. Increasing the fertiliser rate increased seed protein content, simultaneously slightly decreasing oil content. Glucosinolate content of rapeseed slightly decreased with increasing fertiliser but erucic and oleic acid contents were not affected, indicating that increasing the fertiliser rate might not reduce oilseed rape quality. Manipulation of fertiliser level was more effective than altering planting density for increasing seed oil and protein yields. Highest seed oil and protein yields resulted from the highest fertiliser application of 240 kg N, 52.4 kg P, 174.3 kg K, 15 kg S and 1.2 kg B ha^–1, under a planting density of 22.5 × 10⁴ plants ha^–1. Maximum economic gain occurred with the two highest fertiliser levels, whereas planting density has no significant effect on profitability. A balanced application of NPKSB fertilisers should be employed with direct-sowing cultivation of oilseed rape, aimed at building a suitable population structure that balances plant population density and individual growth.

Nutrient deficiencies are considered a reason for commercial yields of wheat (Triticum aestivum L.) and canola (Brassica napus L.) in the high-rainfall zone (HRZ) of southern Australia being well below predicted potential yields. With the aim of developing soil-test interpretation guidelines suitable for HRZ conditions, nutrient-response experiments, 15 with wheat and 12 with canola, were conducted between 2015 and 2018. These experiments quantified responses to nitrogen (N), phosphorus (P), potassium (K), sulfur (S), copper (Cu) and zinc (Zn) in pre-sowing soil tests. The highest yielding treatment of the wheat experiments averaged 7.1 t/ha (range 2.6–10.8 t/ha), and of the canola experiments 4.2 t/ha (range 0.7–6.2 t/ha). The most frequent responses were to N and P, followed by S and K. There were no significant positive responses to Cu or Zn. Across the experiments, the 95% critical value for Colwell P in wheat was 52 mg/kg, with a 95% confidence range of 39–68 mg/kg. For canola, the critical value was 59 mg/kg, with a range of 38–139 mg/kg. These values are higher than from lower rainfall regions of Australia. Critical values for K and S were also higher than from drier regions of Australia. The Sprengel–Lieberg Law of the Minimum overestimated yield where there were multiple nutrient limitations, whereas an equivalent Law of the Product underestimated yield under these conditions. These higher critical values based on evidence from the HRZ are expected to assist in closing the yield gap for wheat and canola in the region.

Achnatherum inebrians is an invasive perennial grass widespread in natural grasslands of north-west China and plays an important role in grassland ecological restoration. The presence of the seed-borne endophytic fungus Epichloë gansuensis in A. inebrians promotes grass growth, increases resistance to abiotic stress, and affects the rhizosphere microbial community of host plants. However, the relationships among E. gansuensis, rhizosphere bacteria and plant contents of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) during different growing seasons are not clear. We examined changes in the rhizosphere bacterial community and in nutrient contents and ratios in A. inebrians with (E+) and without (E−) E. gansuensis in May, August and December. The Shannon diversity index was higher for rhizosphere bacteria of E+ than E− plants in the three different seasons. Leaf C, N and P contents and root P and K contents were higher in E+ than E− plants in May, and leaf K and root C were higher in E+ than E− plants in August. Leaf C : N ratios were lower in E+ than E− plants in December, and leaf C : K ratios were lower in E+ than E− plants in August and December. In addition, our results indicate significant interactions among rhizosphere bacteria, C, N, P and K contents, and endophyte treatment in three different seasons. In conclusion, E. gansuensis enhanced the C, N, P and K contents of host plants, and affected nutrient ratios of A. inebrians probably by increasing rhizosphere bacterial diversity and altering rhizosphere bacterial community structure. This study provides new findings on the ecological function of the endophyte E. gansuensis, including its potential role in enhancing soil fertility. The improvements in soil fertility were utilised in extrapolating to forage grass–endophyte associations.

Soybean mosaic virus (SMV) is a worldwide disease of soybean (Glycine max (L.) Merr.) that can cause serious reduction in yield and seed quality. Soybean cv. Qihuang-1 is an important source of resistance to SMV in China, carrying a resistance gene (R_SC3Q) against SMV strain SC3. In order to discover genes and networks regulated by R_SC3Q-mediated resistance in Qihuang-1, we analysed transcriptome data of a pair of near-isogenic lines, R (R_SC3Q) and S (r_SC3Q), from the cross Qihuang-1 × Nannong 1138-2 (r_SC3Q), after SC3 inoculation. Many differentially expressed genes (DEGs) were identified in the R and S lines at 6, 20 and 48 h post-inoculation. Based on pathway-enrichment analysis of DEGs, three genes encoding calmodulin-like protein (Glyma03g28650, Glyma19g31395 and Glyma11g33790) with downregulated expression in the S line were identified in the plant–pathogen interaction pathway at 6 h post-inoculation. Analyses by quantitative real-time PCR were performed to verify that these three genes were not beneficial for SMV infection. Our results also revealed a complex plant-hormone signal network in R_SC3Q-mediated resistance during the early stage of SMV infection. Expression of jasmonic acid repressor genes (TIFY/JAZ) and abscisic acid-induced genes (PP2C3a) was upregulated in the R line but not the S line. More DEGs related to indole-3-acetic acid were found in the R line than the S line, and no salicylic acid-related DEGs were identified. These results suggest that suppression of jasmonic acid or promotion of abscisic acid is important for R_SC3Q-mediated resistance against SC3, and that salicylic acid may not act as a main regulator of R_SC3Q-mediated resistance during early stages of SC3 infection. Growth and development were greatly affected through R_SC3Q-mediated resistance responses after SC3 infection. Our understanding would be enhanced by identification of factors associated with R_SC3Q that help to trigger the resistance response.

The nitrogen-use efficiency (NUE) of a fertiliser has implications for pasture growth and the environment. This study aimed to compare application of urea as a foliar spray or in granular form, to kikuyu (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone) and short-rotation ryegrass (Italian ryegrass, Lolium multiflorum Lam.) pastures in the subtropical dairy region of eastern Australia. The first experiment was a replicated grazing study on a site with a high plant-available soil N (75 mg nitrate-N/kg). The granular rate of urea was 46 kg N/ha.month equivalent, and the foliar spray rate was 40% of the granular rate. Pasture growth rate (51 DM/ha.day with foliar spray vs 45 kg DM/ha.day with granules) and pasture consumed (4942 vs 4382 kg DM/ha) were not significantly different between treatments. However, over the 8 months of the study, soil nitrate-N levels fell from 75 to 22 mg/kg on the foliar plots but only fell to 60 mg/kg on the granular plots. The second experiment was a replicated plot-cut experiment on a site with a low plant-available soil N (8.7 mg nitrate-N/kg). The NUE for kikuyu grass was similar for all treatments with a mean of 14.8 kg DM/kg N for the four foliar treatments (high and low, with and without wetting agent) and 17.4 kg DM/kg N for the granular treatment. The NUE for the ryegrass was also similar for all treatments, with a mean of 13.2 kg DM/kg N for the foliar treatments and 15.8 kg DM/ha for the granular treatment. A third experiment, evaluating absorption of foliar-sprayed urea over time, found that >80% of the urea applied to kikuyu was absorbed by 7 h; for ryegrass, the amount absorbed was only ∼45% but increased to ∼75% if wetting agent was included. We suggest that the lack of benefit in NUE achieved by applying urea as a foliar spray, which contrasts with results from studies in temperate dairy farm systems, is primarily associated with the substantially lower tiller density and hence the smaller canopy area for absorption of the foliar spray by the new regrowth shoots post-grazing.

Nicotiana alata is resistant to Tomato spotted wilt virus (TSWV) and of great value in breeding. However, hybrid sterility constrains the application of interspecific genetic resources. Previously, we obtained interspecific hybrids between a cytoplasmic male sterility (CMS) line of Nicotiana tabacum and N. alata, some of which were pollen sterile. In the present research, we studied the cytological abnormalities during pollen development in sterile hybrids (F₁-D) by comparing pollen development with that in fertile hybrids (F₁-S) from the same cross. Transmission electron microscopy and DiI staining showed that the membrane structures of microspores and pollen in F₁-D sterile hybrids were impaired. Carbol fuchsin staining revealed that cytomixis, chromosome loss and asymmetric callose wall formation occurred with high frequency in the microsporocytes and microspores of the sterile hybrids. The cytoplasm and nucleus were lost in the microspores and pollen of sterile hybrids, leading to mature pollen grains that were vacuous and collapsed in the aperture region. In addition, delayed tapetum degradation was detected in the anther of sterile hybrids, and sporopollenin was deposited in the aperture region. Impaired membrane structures of microspores and pollen in F₁-D sterile hybrids affected the integrity of the cells, and might be associated with chromosome, nuclear and cytoplasm loss, vacuous pollen, and sterility in F₁-D hybrids. Abnormal tapetum degradation in the anther and irregular sporopollenin deposition in the pollen wall of the F₁-D sterile hybrids might also be related to the pollen sterility. This study deepens our understanding of the cytological mechanisms of hybrid sterility, and may facilitate the application of TSWV-resistant resources in cultivated Nicotiana species through hybrid fertility restoration and backcross breeding.

Intercropping is a major production strategy in the tropics. Sesame (Sesamum indicum L.) and sunflower (Helianthus annuus L.) are two resilient oilseed crops of high economic potential with contrasting growth and morphological characteristics, which may make them suitable candidates for intercropping. Two field trials were conducted during the late cropping season (July–November) of 2018 and 2019 at Abeokuta, Nigeria, to evaluate the effects of organic fertiliser application and varying the introduction date of sunflower into sesame fields on intercrop productivity and efficiency. Sunflower was sown at 0, 10 and 20 days after sowing (DAS) of two varieties of sesame. On average, mixtures that involved either sesame variety with sunflower interplanted at 0 or 10 DAS plus fertiliser application showed a high land-equivalent ratio of >1.00 (biological efficiency), high land-equivalent coefficient of >0.25 (intercrop compatibility), and high economic efficiency in terms of monetary advantage index and sesame yield equivalent. Weight of sesame capsules per plant increased significantly (P < 0.05) following application of organic fertiliser in both years. Similarly, aboveground plant weight of sesame was significantly (P < 0.05) enhanced irrespective of the date of introducing sunflower into sesame fields in both years. Sesame grain yield (543.4–636.5 kg/ha) during the wetter late season of 2019 compared favourably with mean values from Africa (473.5 kg/ha) and the world (512.3 kg/ha). Organic fertiliser application significantly (P < 0.05) enhanced sesame grain yield in both years. Delaying introduction of sunflower until 20 DAS of sesame resulted in significantly (P < 0.05) lower sunflower head weight and achene weight per head and depressed sunflower grain yield in both years. Therefore, mixtures of both sesame varieties with sunflower introduced at 0 or 10 DAS and with organic fertiliser applied achieved high intercrop productivity and land-use efficiency, and are hereby recommended for cultivation under humid tropical conditions.

Sowing date and nitrogen (N) fertilisation modify the morpho-physiological characteristics of maize (Zea mays L.) plants, which can alter the yield. The aim of this study was to analyse the effects of sowing date and N rate on the growth-pattern characteristics of maize hybrids with contrasting cycles, and the subsequent relationship with grain yield. Two experiments were set up in Santa Catarina State, southern Brazil. Two maize hybrids (AG9025, super-early cycle; P30F53, early cycle), two sowing periods (early spring and late spring), and four rates of topdressed N (0, 150, 300 and 450 kg N ha⁻¹) were tested. Plant height, leaf area index (LAI), and relative chlorophyll content (RCC) were evaluated. The increment in N rate increased plant height at the silking stage for early spring sowing, and had no effect for late spring sowing. Higher N rates increased plant height of P30F53 and did not affect plant height of AG9025. Increasing the N rate enhanced LAI and RCC at silking more sharply when maize was sown in early spring. Higher N rates resulted in increased RCC during grain-filling, as well as maintenance of LAI, factors that were strongly associated with grain yield, especially for early spring sowing with hybrid P30F53. This research shows that the use of increasing N rates is an adequate management strategy to increase maize grain yield when the crop is sown in early spring. When applied at this sowing time, N has greater effect on the elevation of LAI and RCC and their maintenance during grain filling.