Zeolite is an abundant potassium (K)-rich silicate mineral that could increase K supply to plants. Potassium deficiency causes lodging problems and yield reductions in paddy fields in China. However, it is unknown whether zeolite amendments alleviate K deficiency or enhance lodging-related stem morphology characteristics in rice. A 2-year field experiment was conducted to evaluate the effect of zeolite amendment (0, 5 and 10 t ha^–1) and K application (0, 30 and 60 kg ha^–1) on rice grain yield, stem morphology, and K nutrient status in soil and plant tissues. In both years zeolite and K application, alone or in combination, significantly increased grain yield, mainly through increased number of panicles per plant with zeolite application and number of spikelets per panicle with K application. In the top 30 cm soil layer, zeolite amendment increased cation exchange capacity by up to 31% and available K by up to 38%. Zeolite or K application alone significantly increased stem, leaf and panicle K concentrations. Zeolite promoted K allocation to rice stems, and improved stem morphology associated with lodging index. In both years, zeolite or K application alone increased stem diameter, dry weight linear density and the breaking resistance moment by up to 7.0%, 8.3% and 16%, respectively, and decreased the stem lodging index by up to 6.7%. In summary, zeolite is an alternative source of K fertiliser and can alleviate K deficiency in paddy fields in China and elsewhere.

Downy mildew caused by Peronospora variabilis is a major fungal disease limiting yield of quinoa (Chenopodium quinoa) around the world. Existing quinoa cultivars do not have adequate levels of resistance to the disease. In the present study, 165 quinoa accessions were screened for resistance to the disease in two consecutive years. Disease ratings were performed by using a three-leaf scoring technique. In 2018, of 70 quinoa accessions, 47.14% were moderately resistant and 18.57% were highly resistant. However, in 2019, of 95 accessions, 44.21% showed moderately resistant reaction and 26.31% highly resistant reaction to the disease. The average of AUDPC (area under disease progress curve) of all the accessions was 1293.42 in 2018, and 931.68 in 2019. The disease caused significant (P < 0.01) cumulative defoliations in susceptible accessions. AUDPC was positively correlated (r = 0.796 in 2018, r = 0.896 in 2019) with defoliation rate and negatively correlated (r = –0.834 in 2018, r = –0.599 in 2019) with plant height. There were also negative correlations (r = –0.755 in 2018, r = –0.580 in 2019) between defoliation rate and plant height. The study not only revealed resistant germplasm but also showed the importance of screening downy mildew resistance by comparing disease-related agronomic characteristics.

Lodging is an important agronomic trait that affects soybean seed yield. In this study, a recombinant inbred line (RIL) population derived from ‘Zhongdou 27’ × ‘Jiunong 20’ (including 112 lines) was used to identify quantitative trait loci (QTL) associated with lodging of soybean. A genetic map of 2050.27 cM was previously constructed using 4412 single nucleotide polymorphism (SNP) bins in this population. Three major QTL were identified in the single environment for 3 years, accounting for 12.38–16.5% of the phenotypic variation. Among these QTL, qldg-1 was stable for 3 years and qldg-2 was stable for 2 years. QTL by environment interactions (QEI) mapping was also used to detect QTL. A total of 14 QTL were detected, which could explain 2.62–11.28% of the phenotypic variation. The constructed residual heterozygous lines (RHL) were used for the verification of qldg-1 and qldg-2, and the results showed that these two QTL could significantly improve lodging resistance. In addition, genes in the confidence interval of qldg-1 and qldg-2 were designed to predict the candidates. The results of quantitative real-time PCR (qRT-PCR) verification of five genes revealed that two genes (Glyma.17G048100 and Glyma.09G239000) were expressed differentially during the dynamic stages between the parents, demonstrating that these two were the candidates associated with soybean lodging. The QTL and candidate genes related to soybean lodging identified in this study will be of great significance to the future soybean molecular-assisted breeding for lodging resistance.

Pod and seed weight per plant (PSW) is one of the most important components of soybean yield. We analysed 147 recombinant inbred lines (RILs) of soybean. Using a combination of simple sequence repeat (SSR) and specific-length amplified fragment (SLAF) high-density maps, we applied composite interval mapping (CIM) and multiple interval mapping (MIM) to map quantitative trait loci (QTLs) for PSW across multiple years (2006–10 and 2013). We mapped 24 QTLs for PSW, with 10 QTLs identified by SSR genetic map and 14 by SLAF genetic map. Five consensus QTLs were integrated, and they were validated by a chromosome segment substitution line (CSSL) population. Furthermore, the functions of all genes located in consensus QTL intervals were predicted; nine candidate genes function directly or indirectly in regulating seed development as well as seed size and weight. Our results lay a foundation for the cloning of candidate genes related to PSW and marker-assisted breeding in soybean.

Improving seed yield and oil quality of oilseed crops can aid in provision of a nutritious diet for humans. A worldwide collection of linseed was evaluated for seed yield (YLD), seed oil (OIL) and protein content (PRO), oil fatty acid composition, omega-3 to omega-6 ratio (ω3/ω6), total tocopherol content (TTC), and total phenolic content (TPC). At 2 years, higher temperature (∼7%) and lower relative humidity (∼16.6%) during the seed filling and maturity period (dryer condition) were correlated with significant decreases in YLD (∼18%) and OIL (∼4.5%), lower contents of linolenic acid (∼13%) and TTC (9.8%), and lower ω3/ω6 ratio (∼31%); oleic (∼9%) and linoleic acid contents (∼23%) and TPC (14.4%) increased. Correlation results demonstrated some significant associations among quantitative traits such as YLD, OIL, and thousand seed weight (TSW); however, the association of these traits with qualitative indices was mostly negative. Genotypes were classified irrespective of their geographical origin and independent of seed or flower colour. In this classification, a yellow-seeded Canadian group had the lowest ω3/ω6 ratio (∼0.05), the highest seed yield and high TTC, whereas groups with the highest ω3/ω6 ratio (>3.0) had the lowest oil TTC and low to average seed yield. Results suggested that some brown-seeded Asian genotypes with high grain yield and oil potential, higher ω3/ω6 ratio, and other more stable oil quality indices are suitable to develop broadly adaptive varieties under the possible fluctuation of climatic factors. Other genetic groups could also be used for breeding programs with specific objectives.

Crop diversity, crop structures and crop residue can modify the seed-bank environment, influencing the seedling emergence of some weeds. The objectives of this work were to analyse (1) the effect of winter crop canopies of canola and wheat and soybean stubble on seedling emergence of Conyza sumatrensis and Raphanus sativus and (2) the effect of different soybean crop structures and soybean stubble on Digitaria insularis and Amaranthus palmeri seedling emergence. Two different field experiments were conducted at Buenos Aires University in a completely randomised factorial design with five replicates. The two winter species showed differences in the emergence timing whereas the two summer species emerged at the same time but with differences between years. Seedling emergence of A. palmeri was reduced by the presence of crop residue while the effect on C. sumatrensis and R. sativus emergence were more variable between years and D. insularis was not affected. Crops did not affect seedling emergence of winter species or that of A. palmeri. However, D. insularis emergence was favoured by soybean presence, mainly with closer canopy structures. Management decisions that promote the presence of crop residues favour the reduction of seedling emergence of palmer amaranth. In contrast, evaluated crop plant densities and planting dates were not able to reduce the seedling emergence of C. sumatrensis, R. sativus and D. insularis. Planting soybean in more competitive crop structures with closer canopies is not a good option due to the improvement of seedling emergence of D. insularis. Crop management decisions that inhibit seedling emergence in some species could stimulate it in others.

Sugarcane has a high yield potential; however, ensiling has been a challenge, and its fibre has low quality for ruminant feed. This study aimed to evaluate increasing levels of a fibrolytic enzymatic blend (300 U xylanase + 300 U cellulase/g) during sugarcane ensiling on fermentative profile, losses, chemical composition, in vitro degradation, and aerobic stability. Forty silos were assigned to four treatments: 0, 200, 400 and 600 mg enzymatic blend/kg sugarcane fresh matter. The trial was performed in a randomised blocked design, in which five sugarcane cultivars were defined as blocks. Silos were performed in 15-L PVC tubes and stored at room temperature for 45 days. Enzyme level did not affect silage pH, ammonia-N, soluble carbohydrates, ethanol, or organic acid concentration. Although increasing enzyme levels linearly increased effluent losses, there was no effect on gas losses or dry matter recovery. Treatment had no effect on silage chemical composition, in vitro degradation, or silage pH after aerobic exposure. However, enzyme treatment quadratically affected silage temperature after aerobic exposure and aerobic stability period. Intermediate levels of enzymes increased silage temperature after aerobic exposure and reduced the aerobic stability period. Therefore, addition of enzymes during sugarcane ensiling shows no effect on silage fermentation, nutritional value or dry matter recovery, but linearly increases effluent losses. Although an intermediate level of enzymes decreases aerobic stability, it has no effect on silage pH after aerobic exposure.

Chemical strategies to manage pest populations that have evolved pesticide resistance can involve killing resistant individuals by using higher rates of the same pesticide or applying alternative pesticides for which resistance does not exist. However, the dilemma is that alternative pesticides available for many pest species are limited, while higher pesticide rates may lead to the evolution of higher resistance levels. Here, both strategies are tested in a resistant population of the redlegged earth mite, Halotydeus destructor, which contained resistance against two groups of chemicals: synthetic pyrethroids and organophosphates. Resistant mites were introduced into exclusion field plots, which were then treated with pyrethroid, organophosphate or alternative chemicals for 2 years at a low pressure (one spray at the registered field rate per year) or a high pressure (two sprays at the registered field rate per year). A single pyrethroid application suppressed mite numbers, but pyrethroid-resistant allele (kdr) frequencies quickly rose from ∼50% to nearly 100%. Thereafter, pyrethroid chemicals lost effectiveness. However, kdr frequencies declined across mite generations when pyrethroids were not used, regardless of other treatments. Organophosphates continued to suppress mite populations under both high and low pressures, irrespective of kdr allele frequencies, and laboratory bioassays showed no increase in organophosphate resistance levels. One of the alternative chemicals, diafenthiuron, applied once per year over two years, successfully suppressed mite numbers, whereas other treatments did not control mites. These findings demonstrate that different strategies are required to manage H. destructor with pyrethroid resistance and organophosphate resistance.