Integrated farming with intercropping increases food production while reducing environmental footprint.

Food security has been a significant issue for the livelihood of smallholder family farms in highly populated regions and countries. Industrialized farming in more developed countries has increased global food supply to meet the demand, but the excessive use of synthetic fertilizers and pesticides has negative environmental impacts. Finding sustainable ways to grow more food with a smaller environmental footprint is critical. We developed an integrated cropping system that incorporates four key components: 1) intensified cropping through relay planting or intercropping, 2) within-field strip rotation, 3) soil mulching with available means, such as crop straw, and 4) no-till or reduced tillage. Sixteen field experiments, conducted with a wide range of crop inputs over 12 consecutive years (2006 to 2017), showed that the integrated system with intercropping generates significant synergies-increasing annual crop yields by 15.6 to 49.9% and farm net returns by 39.2% and decreasing the environmental footprint by 17.3%-when compared with traditional monoculture cropping. We conclude that smallholder farmers can achieve the dual goals of growing more food and lowering the environmental footprint by adopting integrated farming systems.

Cadmium toxicity in plants: Impacts and remediation strategies.

Cadmium (Cd) is an unessential trace element in plants that is ubiquitous in the environment. Anthropogenic activities such as disposal of urban refuse, smelting, mining, metal manufacturing, and application of synthetic phosphate fertilizers enhance the concentration of Cd in the environment and are carcinogenic to human health. In this manuscript, we reviewed the sources of Cd contamination to the environment, soil factors affecting the Cd uptake, the dynamics of Cd in the soil rhizosphere, uptake mechanisms, translocation, and toxicity of Cd in plants. In crop plants, the toxicity of Cd reduces uptake and translocation of nutrients and water, increases oxidative damage, disrupts plant metabolism, and inhibits plant morphology and physiology. In addition, the defense mechanism in plants against Cd toxicity and potential remediation strategies, including the use of biochar, minerals nutrients, compost, organic manure, growth regulators, and hormones, and application of phytoremediation, bioremediation, and chemical methods are also highlighted in this review. This manuscript may help to determine the ecological importance of Cd stress in interdisciplinary studies and essential remediation strategies to overcome the contamination of Cd in agricultural soils.

Co-application of biochar and microorganisms improves soybean performance and remediate cadmium-contaminated soil.

Sole biochar addition or microbial inoculation as a soil amendment helps to reduce cadmium (Cd) toxicity in polluted agricultural soils. Yet the synergistic effects of microorganisms and biochar application on Cd absorption and plant productivity remain unclear. Therefore, a pot experiment was conducted to investigate the combined effect of microorganisms (Trichoderma harzianum L. and Bacillus subtilis L.), biochar (maize straw, cow manure, and poultry manure), and Cd (0, 10, and 30 ppm) on plant physiology and growth to test how biochar influences microbial growth and plant nutrient uptake, and how biochar ameliorates under Cd-stressed soil. Results showed that in comparison to non-Cd polluted soil, the highest reduction in chlorophyll content, photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency, and intercellular CO2 were observed in Cd2 (30 ppm), which were 9.34%, 22.95%, 40.45%, 29.07%, 20.67%, and 22.55% respectively less than the control Cd0 (0 ppm). Among sole inoculation of microorganisms, highest stomatal conductance, water use efficiency, and intercellular CO2 were recorded with combined inoculation of both microorganisms (M3), which were 5.92%, 7.65%, and 7.28% respectively higher than the control, and reduced the Cd concentration in soil, root, and shoot by 21.34%, 28.36%, and 20.95%, respectively, compared to the control. Similarly, co-application of microorganisms and biochar ameliorated the adverse effect of Cd in soybean as well as significantly improved plant biomass, photosynthetic activity, nutrient contents, and antioxidant enzyme activities, and minimized the production of reactive oxygen species and Cd content in plants. Soil amended with poultry manure biochar had significantly improved the soil organic carbon, total nitrogen, total phosphorous, and available potassium by 43.53%, 36.97%, 22.28%, and 4.24%, respectively, and decreased the concentration of Cd in plant root and shoot by 34.68% and 47.96%, respectively, compared to the control. These findings indicate that the combined use of microorganisms and biochar as an amendment have important synergistic effects not only on the absorption of nutrients but also on the reduction of soybean Cd intake, and improve plant physiology of soybean cultivated in Cd-polluted soils as compared to sole application of microorganisms or biochar.

In-season weather data provide reliable yield estimates of maize and soybean in the US central Corn Belt.

Weather conditions regulate the growth and yield of crops, especially in rain-fed agricultural systems. This study evaluated the use and relative importance of readily available weather data to develop yield estimation models for maize and soybean in the US central Corn Belt. Total rainfall (Rain), average air temperature (Tavg), and the difference between maximum and minimum air temperature (Tdiff) at weekly, biweekly, and monthly timescales from May to August were used to estimate county-level maize and soybean grain yields for Iowa, Illinois, Indiana, and Minnesota. Step-wise multiple linear regression (MLR), general additive (GAM), and support vector machine (SVM) models were trained with Rain, Tavg, and with/without Tdiff. For the total study area and at individual state level, SVM outperformed other models at all temporal levels for both maize and soybean. For maize, Tavg and Tdiff during July and August, and Rain during June and July, were relatively more important whereas for soybean, Tavg in June and Tdiff and Rain during August were more important. The SVM model with weekly Rain and Tavg estimated the overall maize yield with a root mean square error (RMSE) of 591 kg ha-1 (4.9% nRMSE) and soybean yield with a RMSE of 205 kg ha-1 (5.5% nRMSE). Inclusion of Tdiff in the model considerably improved yield estimation for both crops; however, the magnitude of improvement varied with the model and temporal level of weather data. This study shows the relative importance of weather variables and reliable yield estimation of maize and soybean from readily available weather data to develop a decision support tool in the US central Corn Belt.

Effects of cultivar and growing degree day accumulations on forage partitioning and nutritive value of common vetch (Vicia sativa L.) on the Tibetan plateau.

BACKGROUND: The use of common vetch in grassland-livestock systems has expanded greatly within recent years, partly because of its value as a high-quality forage crop but also to improve the soil nitrogen availability. In-field estimation of forage yield potential and nutritional characteristics is required for providing management decision to farmers on how to optimize the management and use of common vetch forages. The aim of this work was to study changes in forage partitioning and nutritive value responses of a late-maturing and an early maturing cultivar of common vetch in a two-year study on the Tibetan Plateau. RESULTS: This study provided evidence for differential patterns of forage accumulation for common vetch with contrasting maturity over 2 years. The late-maturing cultivar exhibited greater forage yield and a lower proportion of pods, compared to the early maturing cultivar. There was a tendency towards lower forage nutritive value with the late-maturing cultivar. Regressions of nutritive value parameters of common vetch forages on growing degree days were explained by the cubic (P < 0.001) models, all with high coefficients of determination (R2 ≥ 0.792). CONCLUSION: This study shows that the late-maturing cultivar harvested at end of the pod-filling stage produces high forage yield, increasing the availability of high-quality forage for ruminants, thereby improving the self-sufficiency of farmers, in terms of forage yield and high-concentration protein. For early maturing cultivars, it may be better to harvest at the early flowering stage for better nutritive value and in part to enable a subsequent double crop of oat. © 2020 Society of Chemical Industry.

Artificial Diet Influences Population Growth of the Root Maggot Bradysia impatiens (Diptera: Sciaridae).

In order to investigate the effects of artificial diets on the population growth of root maggot Bradysia impatiens, its population growth parameters were assayed on eight artificial diets (Diet 1, D2, D3, D4, D5, D6, D7, and D8). Results showed that developmental duration from egg to pupa was successfully completed on all eight artificial diets. However, the egg to pupal duration was shortest, while the survival rate of four insect stages was lowest when B. impatiens was reared on D1. When B. impatiens was reared on D7 and D8, the survival rate, female longevity, and female oviposition were higher than those reared on other diets. When B. impatiens was reared on D7, the intrinsic rate of increase (rm = 0.19/d), net reproductive rate (R0 = 39.88 offspring per individual), and finite rate of increase (λ = 1.21/d) were higher for its population growth with shorter generation time (T = 19.49 d) and doubling time (Dt = 3.67 d). The findings indicate that the D7 artificial diet is more appropriate for the biological parameters of B. impatiens and can be used an indoor breeding food for population expansion as well as further research. We propose that vitamin C supplement added to the D7 is critical for the improvement of the B. impatiens growth.

Transcriptome Analysis Reveals Key Cold-Stress-Responsive Genes in Winter Rapeseed (Brassica rapa L.).

Low ambient air temperature limits the growth and selection of crops in cold regions, and cold tolerance is a survival strategy for overwintering plants in cold winters. Studies of differences in transcriptional levels of winter rapeseed (Brassica rapa L.) under cold stress can improve our understanding of transcript-mediated cold stress responses. In this study, two winter rapeseed varieties, Longyou-7 (cold-tolerant) and Lenox (cold-sensitive), were used to reveal morphological, physiological, and transcriptome levels after 24 h of cold stress, and 24 h at room temperature, to identify the mechanism of tolerance to cold stress. Compared to Lenox, Longyou-7 has a shorter growth period and greater belowground mass, and exhibits stronger physiological activity after cold stress. Subsequently, more complete genomic annotation was obtained by sequencing. A total of 10,251 and 10,972 differentially expressed genes (DEG) were identified in Longyou-7 and Lenox, respectively. Six terms closely related to cold stress were found by the Gene Ontology (GO) function annotation. Some of these terms had greater upregulated expression in Longyou-7, and the expression of these genes was verified by qRT-PCR. Most of these DEGs are involved in phenylpropanoid biosynthesis, plant hormone signal transduction, ribosome biogenesis, MAPK signaling pathway, basal transcription factors, and photosynthesis. Analysis of the genes involved in the peroxisome pathway revealed that Longyou-7 and Lenox may have different metabolic patterns. Some transcription factors may play an important role in winter rapeseed tolerance to cold stress, and Longyou-7 is slightly slower than Lenox. Our results provide a transcriptome database and candidate genes for further study of winter rapeseed cold stress.

Plastic Biofilm Carrier after Corn Cobs Reduces Nitrate Loading in Laboratory Denitrifying Bioreactors.

Nitrate-nitrogen (nitrate-N) removal rates can be increased substantially in denitrifying bioreactors with a corn ( L.) cob bed medium compared with woodchips; however, additional organic carbon (C) is released into the effluent. This laboratory column experiment was conducted to test the performance of a postbed chamber of inert plastic biofilm carrier (PBC) after corn cobs (CC) to extend the area of biofilm colonization, enhance nitrate-N removal, lower total organic C losses, and reduce nitrous oxide (NO) production at warm (15.5°C) and cold (1.5°C) temperatures. Treatments were CC only and CC plus PBC in series (CC-PBC). Across the two temperatures, nitrate-N load removal was 21% greater with CC-PBC than CC, with 54 and 44% of total nitrate N load, respectively. However, total organic C concentrations and loads were not significantly different between treatments. Colonization of the PBC by denitrifiers occurred, although gene abundance at the outlet (PBC) was less than at the inlet (CC). The PBC chamber increased nitrate-N removal rate and reduced cumulative NO production at 15.5°C, but not at 1.5°C. Across temperatures and treatments, NO production was 0.9% of nitrate-N removed. Including an additional chamber filled with PBC downstream from the CC bioreactor provided benefits in terms nitrate-N removal but did not achieve C removal. The presence of excess C, as well as available nitrate, in the PBC chamber suggests another unidentified limiting factor for nitrate removal.

Evaluation of Intensive "4R" Strategies for Decreasing Nitrous Oxide Emissions and Nitrogen Surplus in Rainfed Corn.

The "4R" approach of using the right rate, right source, right timing, and right placement is an accepted framework for increasing crop N use efficiency. However, modifying only one 4R component does not consistently reduce nitrous oxide (NO) emissions. Our objective was to determine if N fertilizer applied in three split applications (Sp), by itself or combined with changes in N source and rate, could improve N recovery efficiency (NRE) and N surplus (NS) and decrease NO emissions. Over two corn ( L.) growing seasons in Minnesota, NO emissions ranged from 0.6 to 0.9 kg N ha. None of the treatment combinations affected grain yield. Compared with urea applied in a single application at the recommended N rate, Sp by itself did not improve NRE or NS and did not decrease NO. Combining Sp with urease and nitrification inhibitors and/or a 15% reduction in N rate increased NRE from 57 to >73% and decreased NS by >20 kg N ha. The only treatment that decreased NO (by 20-53%) was Sp combined with inhibitors and reduced N rate. Emissions of NO were more strongly correlated with NS calculated from grain N uptake ( = 0.61) compared with whole-plant N uptake ( = 0.39), possibly because most N losses occurred before grain filling. Optimizing both application timing and N source can allow for a moderate reduction in N rate that does not affect grain yield but decreases NO. Grain-based NS may be a more useful indicator of NO emissions than whole-plant-based NS.

Performance of Agricultural Residue Media in Laboratory Denitrifying Bioreactors at Low Temperatures.

Denitrifying bioreactors can be effective for removing nitrate from agricultural tile drainage; however, questions about cold springtime performance persist. The objective of this study was to improve the nitrate removal rate (NRR) of denitrifying bioreactors at warm and cold temperatures using agriculturally derived media rather than wood chips (WC). Corn ( L.) cobs (CC), corn stover (CS), barley ( L.) straw (BS), WC, and CC followed by a compartment of WC (CC+WC) were tested in laboratory columns for 5 mo at a 12-h hydraulic residence time in separate experiments at 15.5 and 1.5°C. Nitrate-N removal rates ranged from 35 to 1.4 at 15.5°C and from 7.4 to 1.6 g N m d at 1.5°C, respectively; NRRs were ranked CC > CC+WC > BS = CS > WC and CC ≥ CC+WC = CS ≥ BS > WC for 15.5 and 1.5°C, respectively. Although NRRs for CC were increased relative to WC, CC released greater amounts of carbon. Greater abundance of nitrous oxide (NO) reductase gene () was supported by crop residues than WC at 15.5°C, and CS and BS supported greater abundance than WC at 1.5°C. Production of NO relative to nitrate removal (NO) was consistently greater at 1.5°C (7.5% of nitrate removed) than at 15.5°C (1.9%). The NO was lowest in CC (1.1%) and CC-WC (0.9%) and greatest in WC (9.7%). Using a compartment of agricultural residue media in series before wood chips has the potential to improve denitrifying bioreactor nitrate removal rates, but field-scale verification is needed.

Soil Enzyme Activity Behavior after Urea Nitrogen Application.

Understanding how fertilizer application (particularly N, the most used chemical fertilizer worldwide) interacts with soil microbes is important for the development of best management practices that target improved microbial activity to enhance sustainable food production. This study was conducted to determine whether urea N rate and time of application to maize (Zea mays) influenced soil enzyme activity. Enzyme activity was determined by monitoring fluorescein diacetate (FDA) hydrolysis, ß-glucosidase, acid-phosphomonoesterase, and arylsulfatase activities. Experiments were conducted from 2014 through 2016 to compare single (fall or spring applications) and split applications of N at varying N rates under irrigation (Becker) and rainfed conditions (Lamberton and Waseca) in MN, USA. Nitrogen rates varied by location and were based on University of Minnesota guidelines. Soil samples were collected seven times each season. Nitrogen application split into two applications increased FDA activity by 10% compared with fall and spring applied N at Waseca. Fall or spring N application decreased arylsulfatase activity by 19% at Becker and by between 13% and 16% at Lamberton. ß-Glucosidase and acid-phosphomonoesterase activities were unaffected by N application. Sampling time and year had the greatest impact on enzyme activity, but the results varied by location. A negative linear relationship occurred between FDA and ß-glucosidase activity at all three sites. In summary, urea N application had small effects on enzyme activity at the sites studied, suggesting that some form of organic N could be more important than the ammonium provided by urea.

Maize Leaf Appearance Rates: A Synthesis From the United States Corn Belt.

The relationship between collared leaf number and growing degree days (GDD) is crucial for predicting maize phenology. Biophysical crop models convert GDD accumulation to leaf numbers by using a constant parameter termed phyllochron (°C-day leaf-1) or leaf appearance rate (LAR; leaf oC-day-1). However, such important parameter values are rarely estimated for modern maize hybrids. To fill this gap, we sourced and analyzed experimental datasets from the United States Corn Belt with the objective to (i) determine phyllochron values for two types of models: linear (1-parameter) and bilinear (3-parameters; phase I and II phyllochron, and transition point) and (ii) explore whether environmental factors such as photoperiod and radiation, and physiological variables such as plant growth rate can explain variability in phyllochron and improve predictability of maize phenology. The datasets included different locations (latitudes between 48° N and 41° N), years (2009-2019), hybrids, and management settings. Results indicated that the bilinear model represented the leaf number vs. GDD relationship more accurately than the linear model (R 2 = 0.99 vs. 0.95, n = 4,694). Across datasets, first phase phyllochron, transition leaf number, and second phase phyllochron averaged 57.9 ± 7.5°C-day, 9.8 ± 1.2 leaves, and 30.9 ± 5.7°C-day, respectively. Correlation analysis revealed that radiation from the V3 to the V9 developmental stages had a positive relationship with phyllochron (r = 0.69), while photoperiod was positively related to days to flowering or total leaf number (r = 0.89). Additionally, a positive nonlinear relationship between maize LAR and plant growth rate was found. Present findings provide important parameter values for calibration and optimization of maize crop models in the United States Corn Belt, as well as new insights to enhance mechanisms in crop models.

Comparison of root tolerance to drought and aphid (Myzus persicae Sulzer) resistance among different potato (Solanum tuberosum L.) cultivars.

This study was conducted to determine the root system architecture and biochemical responses of three potato (Solanum tuberosum L.) cultivars to drought and aphid (Myzus persicae Sulzer) infestation under greenhouse conditions. A factorial experiment comprising three potato cultivars (Qingshu 9, Longshu 3, and Atlantic), two levels of water (Well watered and drought) application and aphid infestation (Aphids and no aphids) was conducted. The results show that drought stress and aphid infestation significantly increased the root-projected area, root surface area, number of root tips, and number of root forks of all cultivars, relative to their corresponding control plants. The least root projected area, root surface area, number of root tips, and number of root forks occurred on DXY under both drought and aphid infestation. Nevertheless, the greatest root projected area, root surface area, number of root tips and number of root forks occurred on QS9 plants. Moreover, increased SOD, CAT, and POD activities were observed across all cultivars, under drought and aphid stress. The highest SOD, POD, and CAT activities occurred in QS9; under drought and aphid stress, while the least SOD, POD, and CAT activities was observed in DXY. The Atlantic cultivar, which possesses a root system sensitive to water deficit, demonstrated greater resistance to aphid infestation under well-watered and drought-stressed conditions. Conversely, Qingshu 9, which possesses a root system tolerant to water deficit, was highly susceptible to aphids. This study shows that the root architectural and biochemical traits that enhance potato tolerance to drought do not necessarily correlate to a plant's tolerance to aphids.

Synthesis and regulation of auxin and abscisic acid in maize.

Indole-3-acetic acid (IAA), the primary auxin in higher plants, and abscisic acid (ABA) play crucial roles in the ability of maize (Zea mays L.) to acclimatize to various environments by mediating growth, development, defense and nutrient allocation. Although understanding the biochemical reactions for IAA and ABA biosynthesis and signal transduction has progressed, the mechanisms by which auxin and ABA are synthesized and transduced in maize have not been fully elucidated to date. The synthesis and signal transduction pathway of IAA and ABA in maize can be analyzed using an existing model. This article focuses on the research progress toward understanding the synthesis and signaling pathways of IAA and ABA, as well as IAA and ABA regulation of maize growth, providing insight for future development and the significance of IAA and ABA for maize improvement.

No Tillage With Plastic Re-mulching Maintains High Maize Productivity via Regulating Hydrothermal Effects in an Arid Region.

Plastic is a valuable mulching measure for increasing crop productivity in arid environments; however, little is known about the main mechanism by which this valuable technology actuates spatial-temporal changes in soil hydrothermal effect. So a 3-year field experiment was conducted to optimize soil hydrothermal effect of maize field with three plastic mulched management treatments: (1) no tillage with plastic re-mulching (NM), (2) reduced tillage with plastic mulching (RM), and (3) conventional tillage with annual new plastic mulching (CM). The results showed that NM treatment increased soil water content by 6.6-8.4% from maize sowing to seedling stage, than did CM, and it created a good soil moisture environment for sowing of maize. Also, NM had greater soil water content by 4.8-5.6% from maize silking to early-filling stage than had CM, and it made up for the abundant demand of soil moisture for the vigorous growth of maize filling stage. The NM treatment increased water consumption (WC) before maize big-flare stage, decreased WC from big-flare to early-filling stage, and increased WC after early-filling stage. So NM treatment effectively coordinated water demand contradiction of maize at entire growing season. NM decreased soil accumulated temperature (SAT) by 7.0-13.0% at maize sowing to early-filling stage than did CM, but NM had little influence on the SAT during filling stage. In particular, the treatment on NM had smaller absolute values of air-soil temperature differences than RM and CM treatments during maize filling stage, indicating that NM treatment maintains the relative stability of soil temperature for ensuring grain filling of maize. The NM treatment allowed the maize to grow in a suitable hydrothermal status and still maintained high yield. In addition, NM treatment obtained higher net income and rate of return by 6.4-11.0% and 44.1-54.5%, respectively, than did CM, because NM treatment mainly decreased the input costs for plastic and machine operations. Therefore, the NM treatment can be recommended as a promising technique to overcome simultaneous heat stress and water shortage in arid environments.

Managing the trade-offs among yield, economic benefits and carbon and nitrogen footprints of wheat cropping in a semi-arid region of China.

It is critical to understand how farming practices affect the carbon and nitrogen footprints of agricultural production. Grain yield, economic return, and carbon and nitrogen footprints of spring wheat (Triticum aestivum L.) were examined under different tillage-mulch practices. Wheat was grown over 15 years (2002-2016) in the semi-arid region of the western Loess Plateau of China under six tillage-mulch practices: traditional plough with no straw mulching (T), no-till without straw mulching (NT), traditional plough with straw mulching (TS), no-till without straw mulching (NTS), traditional plough with plastic mulching (TP), no-till with plastic mulching (NTP). Average wheat yield over 15 years under NTS, NTP, TP and TS was increased by 28, 24, 22, and 13%, respectively, compared to T. Average net return was greatest under NTS and lowest under TP. The soils under all six tillage-mulch practices gained a considerably large amount of soil organic carbon (SOC) over the 15 yr. The increase in SOC in the 0-30 cm soil layer was greatest under NTS and lowest under T. When changes in soil C were included in the calculations, treatments of NT, TS, NTS, and NTP sharply reduced total greenhouse gas (GHG) emission compared to T. Compared to T, the carbon footprint was decreased by 180, 44, and 123% under NTS, NT, and TS, respectively, but was increased by 153% under TP. Compared to T, the nitrogen footprint was 24-26% lower in TP and NTP, but was not significantly different under NTS, NT, and TS. Therefore, NTS enhanced yield and net return, and reduced GHG and the carbon footprint without increasing the nitrogen footprint, and should be adopted to mitigate the environmental impacts of wheat production in the semiarid Loess Plateau.

Identification of differentially expressed genes involved in amino acid and lipid accumulation of winter turnip rape (Brassica rapa L.) in response to cold stress.

Winter turnip rape (Brassica rapa L.) is an important overwintering oil crop that is widely planted in northwestern China. It considered to be a good genetic resource for cold-tolerant research because its roots can survive harsh winter conditions. Here, we performed comparative transcriptomics analysis of the roots of two winter turnip rape varieties, Longyou7 (L7, strong cold tolerance) and Tianyou2 (T2, low cold tolerance), under normal condition (CK) and cold stress (CT) condition. A total of 8,366 differentially expressed genes (DEGs) were detected between the two L7 root groups (L7CK_VS_L7CT), and 8,106 DEGs were detected for T2CK_VS_T2CT. Among the DEGs, two ω-3 fatty acid desaturase (FAD3), two delta-9 acyl-lipid desaturase 2 (ADS2), one diacylglycerol kinase (DGK), and one 3-ketoacyl-CoA synthase 2 (KCS2) were differentially expressed in the two varieties and identified to be related to fatty acid synthesis. Four glutamine synthetase cytosolic isozymes (GLN), serine acetyltransferase 1 (SAT1), and serine acetyltransferase 3 (SAT3) were down-regulated under cold stress, while S-adenosylmethionine decarboxylase proenzyme 1 (AMD1) had an up-regulation tendency in response to cold stress in the two samples. Moreover, the delta-1-pyrroline-5-carboxylate synthase (P5CS), δ-ornithine aminotransferase (δ-OAT), alanine-glyoxylate transaminase (AGXT), branched-chain-amino-acid transaminase (ilvE), alpha-aminoadipic semialdehyde synthase (AASS), Tyrosine aminotransferase (TAT) and arginine decarboxylase related to amino acid metabolism were identified in two cultivars variously expressed under cold stress. The above DEGs related to amino acid metabolism were suspected to the reason for amino acids content change. The RNA-seq data were validated by real-time quantitative RT-PCR of 19 randomly selected genes. The findings of our study provide the gene expression profile between two varieties of winter turnip rape, which lay the foundation for a deeper understanding of the highly complex regulatory mechanisms in plants during cold treatment.

Timing and rate of nitrogen fertilization influence maize yield and nitrogen use efficiency.

Timing and rate of nitrogen (N) fertilizer application can influence maize (Zea mays L.) grain yield, N uptake, and nitrogen use efficiency (NUE) parameters, but results have been inconsistent across the upper Midwest. This study compared single (fall and preplant) and split applications of differing N rates for maize under irrigated conditions on loamy sand at Becker, MN and under rainfed conditions on loam and clay loam soils at Lamberton, MN and Waseca, MN, respectively, in 2014 to 2016. Fall and preplant applications of N were applied at recommended and 125% of recommended rates (RN) according to University of Minnesota guidelines. Split-application treatments included a two-way (Sp, applied at 75% and 100% of RN) and a three-way split (TSp applied at 50%, 75%, and 100% of RN), with the total N rate equally split among application times. At Becker, maize grain yield with TSp was 12.6 to 15.7 Mg ha-1 among years and significantly greater than that with fall or preplant treatments. The TSp treatment also improved agronomic efficiency (AE) and recovery efficiency (RE) by an average of 30% over fall or preplant treatments. At Lamberton, maize grain yield, AE and RE did not differ among treatments. However, TSp75 improved AE by 8.3 kg kg-1 while producing comparable yields to fall and preplant treatments. At Waseca, Sp or TSp improved grain yield and AE compared with fall treatments. These results suggest that split applications of N can increase maize grain yield, AE, and RE on irrigated coarse-textured soils and applying N fertilizer near planting or as a split application can improve N management on non-irrigated clay loam soils.

Host plant nutrient contents influence nutrient contents in Bradysia cellarum and Bradysia impatiens.

The chive maggot Bradysia cellarum and the fungus gnat B. impatiens are two primary root pests of plants, which can coexist on the same host plants and are the devastating pests on liliaceous crops and edible fungi. Their growth and development are affected by the nutrient contents of their host plants. In this study, we assessed the effects of different host plant nutrients on the nutrient contents of these two Bradysia species. The nutrients of the chive (Allium tuberosum Rottl. ex Spreng.), board bean (Vicia faba L.), lettuce (Lactuca sativa L. var. ramosa Hort.), cabbage (Brassica oleracea L.), wild cabbage (Brassica oleracea var. capitata rubra) and pepper (Capsicum annuum L.) roots were determined, and their effect on nutrient content of the two Bradysia species after feeding on the host plant for three continuous generations were evaluated. The results show that chive and B-bean contained higher levels of protein, free amino acid, soluble sugar and starch than others. As a result, the soluble sugar, fat and protein contents were significantly higher in both Bradysia species reared on chive and B-bean than on cabbage, lettuce, W-cabbage and pepper, suggesting nutritional preference of these insects. Based on our results, we concluded that the two Bradysia species displayed nutrient preference toward chive and B-bean, which provides a reference for understanding their host plant range and for control of the insect species via field crop rotations.