Recent advances in agronomy include better understanding of biodiversity in the ecosystem and mechanisms of interactions between crop species. Intercropping encompasses two or more crop species growing together. Enhanced biodiversity in intercropping systems can increase productivity, stability, resilience, and resource-use efficiency of the intercropped species compared with sole-cropping. Feasibility of different wheat–rapeseed intercropping patterns were evaluated under three nitrogen fertilizer rates (0, 60, and 120 kg N ha^-1) across two experimental years. Besides sole-cropping of wheat (1:0) and rapeseed (0:1), three patterns of wheat–rapeseed intercropping were arranged in different ratios, including 3:1, 1:1, and 1:3. Rapeseed growth and development were influenced highly by inter-annual weather variability, which resulted in a low yield in the second year of the experiment. Total cropping system performance, as indicated by dry matter (per plant and per unit area) and grain yield production, increased with adding N fertilizer, especially in the drier year. Additional N fertilizer could only compensate the yield loss due to intercropping in that year. In terms of individual crop production, sole-cropping of wheat was superior to all intercrops under the environmental conditions of the Pannonian region. Overall, among wheat–rapeseed intercropping patterns, the ratio of 3:1 had advantages over the other intercropping patterns in terms of productivity and interspecies competition across contrasting years.

Pyrus betulifolia Bunge belongs to the woody plant family and is an ideal model for studying molecular strategies of iron acquisition and metabolism in strategy I plants. Using polymerase chain reaction amplification technology, a gene encoding a putative ferric chelate reductase (FCR) protein was isolated from P. betulifolia and designated as PbFRO2. This gene was 2166 bp in length with an open reading frame encoding a protein of 721 amino acids. A hidden Markov model for topology prediction of PbFRO2 suggested that there were 10 transmembrane regions (I–X) connected by nine loops. Phylogenetic analyses demonstrated that PbFRO2 had the highest homology with Malus xiaojinensis Cheng & Jiang. Iron starvation induced significant increase in root FCR activity and PbFRO2 expression. The split-root experiment demonstrated that Fe limitation in one portion of the root system triggered significant up-regulation of the PbFRO2 expression in the Fe-sufficient part, suggesting that the PbFRO2 expression was induced by systemic signals. Furthermore, the addition of α-naphthaleneacetic acid was found to strengthen the Fe deficiency-caused up-regulation of the PbFRO2 expression in the roots. By contrast, 1-naphthylphthalamic acid application blocked up-regulation of the PbFRO2 expression. The results indicated that Fe deficiency-induced alterations of the PbFRO2 expression were mediated by auxin.

To explore candidate genes responsible for the blue color of Selaginella uncinata (Desv. ex Poir.) Spring leaves, we used transcriptome sequencing to compare differential gene expressions in blue and red S. uncinata leaves selected based on morphological observations and pigment content. In total, we obtained 30 119 unigenes with an average length of 1133 bp, and we identified 1442 differentially expressed genes (DEGs). Among the 1442 DEGs, 886 were upregulated and 556 were downregulated in blue leaf samples. After verification of expression by quantitative real-time polymerase chain reaction (qRT-PCR) analysis, seven key enzymes and their encoding genes were identified as being involved in the chlorophyll and flavonoid metabolism pathways. These genes included Mg-chelatase (CHLH), light-dependent NADPH-Pchlide oxidoreductase (LPOR), chlorophyllase (Chlase; CLH), hydroxycinnamoyltransferase (HCT), chalcone synthase (CHS), MYB, and flavonoid 3'-hydroxylase (F3'H), which may be involved in the blue leaf coloration of S. uncinata. Results from this study implied that the primary pathway of pigment metabolism in S. uncinata may be the chlorophyll metabolism pathway rather than the anthocyanin biosynthesis pathway. It is possible that chlorophyll b (Chl b) may be transformed into chlorophyll a (Chl a) by an alternative pathway in which it is converted to Chlorophyllide b by CLH, and then transformed to Chl a without the involvement of CBR or HCAR.

Among dioecious plant species, it is common for the males to grow faster than the females. In this study, we investigated the effects of gender on the growth and wood properties of Salix suchowensis Cheng ex Zhu. using a full-sib pedigree. We observed that the segregation of sex followed a 1:1 ratio and that gender significantly affected growth traits, including tree height, ground diameter, and biomass production. Additionally, the females generally performed better than the males, which is in contrast to the common scenario for dioecious plant species. There is currently relatively little information regarding gender effects on wood properties. Therefore, we also measured the basic wood density and cellulose, hemicellulose, and lignin contents. We determined that any differences between the male and female trees regarding these wood property traits were insignificant. Recent studies revealed that the sex of willow trees is controlled by a ZW sex determination system in which the female is the heterogenic gender. Because female heterogamety is relatively rare in higher plants, our findings may be relevant for characterizing the gender effects on biological performance in dioecious plants regulated by the ZW sex determination system.

A 3-yr orchard study was conducted on Tehranivee, an advanced selection of sweet cherry [Prunus avium (L.) L.] on Mazzard and Gisela 6 rootstocks, to determine the efficacy of different prohexadione-calcium (P-Ca) and ethephon (ETH) treatments on vegetative growth. In experiment 1, cherry trees were treated with 123 or 246 mg L^-1 P-Ca, which was sprayed on 16 and 30 d after full bloom (DAFB) or 16, 30, and 44 DAFB. In experiments 2 and 3, trees were treated before (-6 DAFB) and after (7 and 24 DAFB) bloom with P-Ca and rates similar to experiment 1, as well as with tank-mixed sprays of 123–246 mg L^-1 P-Ca and 175 mg L^-1 ETH applied at various timings. P-Ca alone or in combination with ETH decreased the vegetative shoot growth by up to 74% compared with the untreated control, but this varied by cultivar and year, as well as by plant growth regulator application rate, frequency, and timing. Lower rates of P-Ca at 123 mg L^-1 were as effective as 246 mg L^-1. No benefit was observed in applying P-Ca before bloom before active shoot growth had begun.

Although dry bean (Phaseolus vulgaris L.) is a legume capable of fixing nitrogen, fertilizer N is usually recommended for its production in Canada because it is believed to be an inefficient N fixer. Using genotypes with high N use efficiency (NUE) would reduce the amount of applied N, which usually has deleterious environmental effects. We evaluated 22 bean genotypes for N uptake efficiency (NUpE) in a greenhouse trial and 16 genotypes for N use efficiency (NUE) and its components: NUpE and N utilization efficiency (NUtE) in two seasons (2012 and 2013) of a field trial at 30 kg N ha^-1 (30N) and 100 kg N ha^-1 (100N) soil levels. Root biomass and surface area were highly correlated with NUpE in the greenhouse, where NUpE at 100N was 48% lower than that at 30N. In the field trial, grain yield was highly correlated with NUpE and NUtE at both 30N and 100N. The NUpE at 100N was 65% lower than that at 30N, and NUE at 100N was 68% lower than that at 30N. The low NUE at 100N in the field trial was mainly due to the difference in NUpE. This study also identified nine genotypes, including five germplasm lines (PI 136692, GH-196, UNS-117, UI-239, and LEF2RB) and four cultivars (Othello, Viva, AC Redbond, and Island), that were both N-efficient (at 30N) and N-responsive (to 100N).

The plant hormone ethylene and the gaseous signaling molecule nitric oxide (NO) are involved in numerous plant growth and development processes. However, the mechanisms by which their interaction affects adventitious root development in plants is still not adequately studied. In this experiment, the interaction of ethylene and NO in the adventitious rooting process of marigold (Tagetes erecta L. cv. Marvel) was investigated. Treatments with different dosages of ethylene-releasing ethephon (Ethrel^®, Bayer Crop Science, Leverkusen, Germany) significantly affected the formation of adventitious roots. The greatest rooting ability was observed in 10 μM ethephon-treated explants. It was further shown that the effect of ethylene could be blocked by the specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO), nitric oxide synthase (NOS), enzyme inhibitor N^G-nitro-l-Arg-methyl ester (l-NAME), and nitrate reductase inhibitor (NaN₃). Moreover, ethephon treatments induced an increase in the endogenous NO levels and significantly improved activities of NOS and nitrate reductase (NR) during rooting. Thus, the induction of adventitious roots by ethylene may be through enhancing the levels of NO. Enzymatic pathway NOS and NR could be responsible for ethylene-induced NO production. Furthermore, ethylene and NO treatments at the appropriate dosage may increase the activities of indoleacetic acid oxidase, peroxidase, and polyphenol oxidase. Our work suggests that the stimulation of adventitious roots by ethylene relies on internal generation of NO.

Gibberellic acid (GA_{4 7}) and the cytokinin 6-benzyladenine (6-BA) are used during bloom and fruit set to reduce russeting and improve typiness of select apple cultivars. The gibberellin synthesis inhibitor prohexadione-calcium (P-Ca) is used at the same developmental stage to reduce vegetative growth and susceptibility to fireblight. The use of GA_{4 7}/6-BA for enhancing the typiness of Gala apples and the interaction of GA_{4 7}/6-BA and P-Ca was investigated in a 2-yr experiment on mature Royal Gala/Bud 9 trees. Six treatments were imposed: (i) untreated control; (ii) 5.5 mg L^-1 of GA_{4 7} and 6-BA; (iii) 11 mg L^-1 of GA_{4 7} and 6-BA; (iv) 21 mg L^-1 of GA_{4 7} and 6-BA; (v) 123 mg L^-1 P-Ca; and (vi) a tank mixture of 21 mg L^-1 GA_{4 7}/6-BA and 123 mg L^-1 P-Ca. Trees treated with P-Ca had 21%–45% less growth than the untreated trees or trees treated with GA_{4 7}/6-BA. In one of two years, the addition of GA_{4 7} and 6-BA tank-mixed with P-Ca reduced the efficacy of P-Ca on shoot growth. GA_{4 7}/6-BA decreased soluble solids and fruit firmness in 1 yr, suggesting a delay in fruit maturity. P-Ca alone reduced scarf skin by 7%–10%; however, this effect was negated when combined with GA_{4 7} 6-BA in one of the two years. GA_{4 7} 6-BA increased fruit typiness and length to diameter ratios.

Diverse crop rotations are an integral component of sustainable agriculture. The objectives were to investigate row and forage crop rotation effects on stover biomass, grain yield, and mineral nutrient concentrations of maize (Zea mays L.) grown under a maize–soybean [Glycine max (L.) Merr.] 2-yr rotation (C–S); maize–soybean–spring wheat (Triticum aestivum L.) 3-yr rotation (C–S–W); maize–soybean–oat/pea (Avena sativa L./Pisum sativum L.) hay 3-yr rotation (C–S–H); and maize–soybean–oat/pea hay underseeded with alfalfa (Medicago sativa L.) – alfalfa – alfalfa 5-yr rotation (C–S–H/A–A–A). Rotations were established in 1997 and maize plots were sampled in 2008–2011. Across the 4 yr of the study, grain yield was 10% greater (1.0 Mg ha^-1) in C–S–H/A–A–A and C–S–W rotations compared with C–S with C–S–H intermediate. Under C–S–H/A–A–A, kernel N concentration was 7% greater, kernel P was 17% less, and kernel K was 7% less compared with C–S–W. Kernel Zn concentration was 16% lower in C–S–H than in C–S and C–S–H/A–A–A. Thus, diversification of the C–S rotation with wheat (C–S–W) increased yield while conserving kernel P and K concentration, whereas diversification with oat/pea hay alfalfa (C–S–H/A–A–A) increased grain yield and kernel N concentration but decreased both kernel P and kernel K concentration.

The objectives of this study were to evaluate the efficacy of pendimethalin applied pre-emergence (PRE) followed by post-emergence (POST) application of imazethapyr imazamox/quizalofop-p-ethyl for weed control and their effect on conventional soybean injury, yield attributes, and yield. Field experiments were conducted in 2013 and 2014 in conventional soybean. Herbicide treatments provided ≥90%, 70%, and 85% control of crowfoot grass, large crabgrass, and goosegrass, respectively, and ≤80% control of false amaranth and horse purslane at 30 d after sowing (DAS). At 60 DAS, pendimethalin applied alone or followed by hand-hoeing/quizalofop-p-ethyl/imazethapyr imazamox provided 100% control of goosegrass and 65%–100% control of crowfoot grass/large crabgrass. Pendimethalin followed by imazethapyr imazamox/quizalofop-p-ethyl as well as quizalofop-p-ethyl applied alone resulted in complete control of crowfoot grass, large crabgrass, and goosegrass, but control of broadleaf weeds was variable. Pendimethalin followed by imazethapyr imazamox at 70 g ha^-1 at 28 DAS, imazethapyr imazamox at 60 or 70 g ha^-1 at 21 DAS followed by quizalofop-p-ethyl at 37.5 g ha^-1 at 42 DAS resulted in soybean branch numbers per plant, number of pods per plant, and soybean seed yield comparable to weed-free control. Control of Benghal dayflower and purple nutsedge was not acceptable.

The mitochondrial–nuclear interaction is essential for cellular homeostasis and proper function. DNA methylation plays an important role in gene expression regulation, as well as in maintaining genomic stability. Isonuclear-alloplasmic and isoplasmic-allonuclear lines were used as materials in this study. The mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) from maize tassels were used for DNA methylation analysis with high-performance liquid chromatography. The results were as follows. (i) Different mtDNA methylation levels were detected within the isoplasmic-allonuclear lines and varied nDNA methylation levels were also detected among the isonuclear-alloplasmic lines. (ii) From the pollen mother cell stage to the binucleate stage, the change pattern of DNA methylation levels varied among cytoplasmic male sterility (CMS) lines CMS-C, CMS-T, and CMS-S (CMS Charrua, Texas, and USDA, respectively). The DNA methylation level peaked at the tetrad stage for the CMS-C line, at the mononuclear stage for the CMS-T line, and at the binucleate stage for the CMS-S line. Interestingly, the peaked periods for DNA methylation level just meet their critical abortive periods of CMS-C, CMS-T, and CMS-S lines. Finally, (iii) the change trends of methylation levels for both mtDNA and nDNA are highly consistent for every experimental material. Based on these results, we speculated that the epigenetic status affected by mitochondrial–nuclear interaction may be involved in the regulation of maize CMS.

Soybean agglutinin (SBA), a major anti-nutritional factor in soybeans, seriously affects the safety of and effects on feed animals. Soybean varieties with lower SBA contents could play a positive role in the promotion of the fodder industry. In the present study, one male parent, Hefeng 45, was used in three recombinant I bred line (RIL) populations to detect quantitative trait loci (QTL) associated with SBA content across three different environments. As a result, a total of six, six, and four QTL related to SBA content were identified in the groups Hefeng 45 × Zhongdou 27 (HZ), Hefeng 45 × Dongnong 48 (HD), and Hefeng 45 × Taipingchuan Blacksoy (HT), respectively. Most of the QTL underlying SBA explained less than 10% of the phenotypic variation, but some major QTL with higher additive effects have stable expressions across different environments and RIL populations. On the contrary, many QTL dependent on the environment or RIL populations showed mainly weak effects, and gene × environment interaction occurred in the opposite direction to additive effects and (or) epistasis effects. Two (SbaHZC1-1 and SbaHZD1b-1, linked to Satt139 and Satt189, respectively) and one (SbaHDD1a-1, linked to Satt402) QTL for SBA were identified in HZ and HD populations, respectively, across three environments. Those QTL (Satt139 and Satt189) might have potential in the application of marker-assisted selection for low agglutinin content soybean.

Aconitase catalyzes the reversible isomerization of two tricarboxylic acids, citrate and isocitrate, during the Krebs cycle. Five aconitase genes, namely, Aco1, Aco2, Aco3, Aco4, and Aco5, have been identified in soybean. Previously, Aco4 was mapped on chromosome 11. The purpose of this investigation was to isolate and sequence the candidate gene for Aco4. We mapped the Aco4 gene to a 148 kb region on chromosome 11 that contained 19 predicted genes. One of these, Glyma.11G080600, codes for aconitate hydratase. Sequencing of two isozyme variants (A-line and B-line) for Glyma.11G080600 revealed three synonymous and two non-synonymous substitutions. Perhaps, the two non-synonymous substitutions resulted in a variable isozyme pattern between the variants. Glyma.11G080600 contains a catalytic domain and a swivel domain that are known to catalyze isomerization of citrate to isocitrate and swiveling conformational change in the enzyme mechanism, respectively. Conservation of both the domains implies the role of Glyma.11G080600 in the interconversion of citrate and isocitrate. Glyma.11G080600 is expressed in most tissues, with maximum expression in leaves. Phylogenetic analysis of 25 genes from different species displayed three major clusters. Glyma.11G080600 (Aco4) and Glyma.01G162800, which are conserved in Glycine max (L.) Merr. and Glycine soja Siebold. & Zucc., may have common ancestry before G. max and G. soja split.

Synthetic hexaploid wheat (SHW; genome AABBDD) was derived from a cross of Triticum turgidum L. (BBAA) with Aegilops tauschii Coss. (DD). Systematic investigations of the effects of allohexaploidization on zinc (Zn), iron (Fe), and selenium (Se) accumulation are still lacking. Here, the Fe, Zn, and Se concentrations in SHW lines and their tetraploid and diploid parents were compared in a hydroponic culture experiment. Triticum turgidum showed larger genotypic variation of Zn and Fe concentrations than SHW and A. tauschii. The Se concentration of A. tauschii was significantly higher while its Zn and Fe concentrations were lower than in tetraploid wheat and SHW. Although the Zn and Fe concentrations of some SHW lines increased approximately 20%, no SHW line showed a higher Se concentration than its high-value parent. However, because of the generally increased biomass in SHW lines, the total Se content per plant of most SHW lines was higher than their high-value parents. These new SHWs with high micronutrient content provide novel resources for biofortification breeding. Additionally, the micronutrient concentrations in some SHW lines were not consistent with those in their parents, indicating heterosis or non-additive effects that might result from interaction among the A, B, and D genomes after allopolyploidization.

A premix of atrazine, bicyclopyrone, mesotrione, and S-metolachlor has recently been commercialized for pre-emergence (PRE) and early post-emergence (POST) control of broadleaved and annual grass weeds in corn in the United States. Field and greenhouse dose-response bioassays were conducted in 2015 and 2016 to evaluate the response of glyphosate-resistant (GR) horseweed to this premix applied before or after emergence (PRE or POST). In a field PRE study, the 90% effective doses (ED₉₀) were 2613 and 2863 g a.i. ha^-1 at 14 and 35 d after treatment (DAT), respectively, which were comparable to the labeled rate (2900 g a.i. ha^-1) of the premix. Under greenhouse conditions, POST applications made at the labeled rate to 8–10 or 15–18 cm diameter horseweed rosettes provided ≥97% control. The ED₉₀ values for the in-field POST dose-response study were ≥3431 and ≥6717 g a.i. ha^-1 for the 8–10 and 15–18 cm tall GR horseweed, respectively. At 14 DAT, the premix applied at the labeled rate provided 85% and 68% control of 8–10 and 15–18 cm tall GR horseweed, respectively. The root mean square error for the log-logistic model ranged from 4.2 to 9.2 and the model efficiency coefficient values were ≥0.94 (∼ 1.00), indicating a good fit for the prediction model. In conclusion, a new premix applied before emergence (PRE) will effectively control GR horseweed at the labeled rate compared with POST applications made to ≥8 cm tall plants.

A field experiment was conducted from 1994 to 2013 at Scott, SK, to assess the effects of cropping diversity and inputs on spring wheat, canola, and barley yield in the context of growing season precipitation (GSP), growing degree days (GDD), and terrain attributes. Main-plot treatments consisted of three levels of agricultural inputs [organic (ORG), reduced (RED), and high (HI)] and sub-plot treatments consisted of three levels of cropping diversity [low (LOW), diversified annual grains (DAG), and diversified annual perennial]. Yield was highest for the HI and RED inputs, and lower for the ORG system. The HI–DAG, HI–LOW, RED–DAG, and RED–LOW rotations produced the highest yields. April precipitation was identified as a primary yield-driving factor in this study. April precipitation and fixed effects accounted for up to 22% and 10% of yield variation, respectively, in analyses by 6-yr periods. Terrain attributes explained up to 4.5% of variation in annual yield. The effects of inputs and diversity on crop yield were influenced by GSP, GDD, and terrain attributes and show the importance of crop management in the context of environmental variability.

AAC Bullet is a white-hulled, covered spring oat (Avena sativa L.) cultivar bred by the Ottawa Research and Development Center (ORDC), Agriculture and Agri-Food (AAFC). It was supported for registration by the Ontario Cereal Crops Committee (OCCC) in January 2011 and registered in Canada on 29 Oct. 2012 (CFIA registration no. 7251). In Ontario, AAC Bullet had significantly higher yield, better lodging resistance, and better resistance to crown rust but more days to heading than the control cultivars. From 2011 to 2015, AAC Bullet yielded 16% and 10% higher than trial means in southern and central Ontario, respectively, and has become one of the most popular oat cultivars in these regions.