Maize Yield Loss Research Articles

Performance of Peddapuram Station Maize Pre Release Hybrids to different diseases in all India testing during Kharif 2022

Diseases caused by pathogens are one among the major causes of yield loss in maize. These diseases not only affect its yield but can greatly impair the quality and year-wise stability of production, undermining the efforts to promote sustainable agriculture. Moreover, environmental and health hazards, resulting from the non-judicious application of numerous chemical fungicides are another cause of concern. Though maize is affected by more than 60 diseases, in India about a dozen are of serious concern. The four major diseases viz; turcicum leaf blight (TLB), maydis leaf blight (MLB), post-flowering stalk rots (PFSR), and banded leaf and sheath blight (BLSB) are of national importance. Host plant resistance (HPR) is considered to be most practical, feasible and effective way to control plant diseases. Though diseases can be managed through chemicals, these are neither farmer- nor environment-friendly. These are serious threat to soil and human health too. Further use of chemicals makes maize cultivation costly, reducing profit margin. Therefore, exploitation of HPR helps in minimizing inoculum in soil and yield loss in an eco-friendly and economic manner. One of the best approaches to address different diseases is to identify highly tolerant or resistant genotypes that can be used for genetic improvement. In present investigation three hybrids PH 22-420146, PH 22-420186 and PH 22-420208 were screened against major diseases of maize in different locations in India, among these PH 22-420208 showed resistance to Fusarium stalk rot, Curvularia leaf spot, sorghum downy mildew, Rajasthan downy mildew diseases and moderately resistance to maydis leaf blight, Charcoal rot and banded leaf and sheath blight diseases.

Effect of Irrigation Scheduling Methods on Maize Grain Yield and Nitrate Leaching in Central Minnesota

Highlights Four irrigation scheduling methods were compared for maize yield vs nitrate-N losses. Yield was similar with SM, CB, and EPIC, and lower for IMA irrigation scheduling. Nitrate-N leaching losses were highly dependent on precipitation as well as on the rate and frequency of irrigation. IMA and EPIC methods should be adopted with further calibration. ABSTRACT. Coarse-textured soils in the Great Lakes states have limited water holding capacity, which makes irrigation essential to obtain optimum yields for maize; however, excess irrigation has the potential to contaminate ground and surface water resources through deep seepage of applied fertilizers, making irrigation management critical. The objective of this study was to evaluate the impact of different strategies for agricultural irrigation water management on maize grain yield and nitrate leaching losses. In this three-year study (2019-2021), the following four irrigation scheduling strategies were compared under continuous maize cropping systems at two sites in Central Minnesota, Becker and Westport: (1) soil moisture monitoring using soil moisture sensors (SM), (2) checkbook method of irrigation scheduling (CB), (3) irrigation management assistant tool (IMA), and (4) EPIC model auto-irrigation (EPIC). Overall, in comparison to the CB method (highest irrigation method), the SM, IMA, and EPIC methods recommended 2.58%, 51.05%, and 9.27% less water in irrigation, respectively. In terms of grain yield, no significant differences were observed between irrigation treatments at the Becker site. The average maize grain yield at the Becker site was 12.02, 11.97, 11.76, and 10.62 Mg/ha, for SM, CB, EPIC, and IMA treatments, respectively. However, in the drier 2021 season, a grain yield loss of 30%, 27%, and 21% was observed under IMA when compared to SM, CB, and EPIC methods, respectively, at the Becker site. At the Westport site, on average, no significant difference in yield was obtained between SM, CB, and EPIC, however, yield under IMA treatment was significantly lower (12%) than CB. The results suggest that nitrate leaching losses can be significantly reduced by altering the rate and frequency of irrigation. IMA treatment resulted in significantly lower nitrate leaching (62%) than the CB method, reducing nitrate leaching from 35.86 kg/ha to 13.71 kg/ha at the Westport site. No significant differences in nitrate leaching were observed at the Becker site because the impact of precipitation superseded the impact of irrigation. Results from this study can aid in the adoption and further development of less labor-intensive and more accurate methods of irrigation scheduling in coarse-textured soils of Great Lakes states. Keywords: Coarse textured soils, Crop evapotranspiration, Irrigation scheduling methods, Maize grain yield, Nitrate-N leaching, Water quality, Water quantity.

Predatory effects on the dynamics of Spodoptera Frugiperda infestations in maize

Maize remains in demand due to its nutritive value, capacity to provide food for a growing world population, contribution to food security, and increase in worldwide investments in ethanol as a biofuel. However, the invasion and widespread infestation of Spodoptera frugiperda result in significant maize yield losses, leading to a lower standard of living and a weakened economy for maize producers. This study builds differentiable equations to simulate the behavior of the Spodoptera frugiperda-maize biomass model, incorporating predators and best farming practices. The model exhibits six points of equilibrium, all of which are locally asymptotically stable if the necessary requirements are met. Latin Hypercube Sampling (LHS) and PRCC multivariate analysis were employed to identify the sensitive parameters affecting the pest. Numerical simulations suggest that, in the early stages, integrating natural enemies with best farming practices proves to be an effective intervention as it directly reduces the pest population and promotes sustainable pest control.

Marker-assisted pyramiding of southern leaf blight resistance QTLs qSLB3.1 and qSLB8.1 in maize (Zea mays)

Southern leaf blight (SLB) is one of the major diseases that cause substantial yield losses in maize (Zea mays L.) worldwide. Stacking broad-spectrum resistance genes/QTLs into prevalent cultivars is the prerequisite for durable disease resistance breeding programme. Therefore, a study was carried at the research farm and molecular biology laboratory of School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab during 2017–21 to introgress SLB resistance QTLs from two donors, viz. CM139 (qSLB3.1) and LM5 (qSLB8.1) into CM140 inbred using marker-assisted backcross breeding (MABB). Crosses were made between CM139 × CM140 and LM5 × CM140 to generate two separate F1s. Each F1 was backcrossed twice to generate BC2F1 progenies. Foreground selection was performed at each step using linked flanking markers to each QTL and also evaluated for SLB resistance. The selected heterozygous BC2F1 plants from each cross were inter-crossed to combine qSLB3.1 and qSLB8.1 in the same genetic background. The F2 population was also evaluated phenotypically for SLB resistance and other morphological traits. A total of 18 plants were obtained having both the QTLs with homozygous donor alleles. The F2 plants having both QTLs and singly in the homozygous state were advanced to generate F3 progenies. The pyramided lines exhibited 29% lesser disease severity than the lines with either QTL. The present results indicated that additive effects of the QTLs for SLB resistance played an important role among these lines. To our best knowledge, this is the first report for the pyramiding of QTLs associated with SLB resistance. The pyramided lines would serve as potential donors in maize breeding programs.

Insights from the biogeographic approach for biocontrol of invasive alien pests: Estimating the ecological niche overlap of three egg parasitoids against Spodoptera frugiperda in China

Spodoptera frugiperda, the fall armyworm, causes major damage to maize and >80 other crops worldwide. Since S. frugiperda successfully invaded China in 2018 via long-distance migration from Myanmar, it has caused major maize yield losses and posed a severe threat to maize production and food security. The biocontrol approach for S. frugiperda using natural enemies is environmentally safe and effective. Estimating the potential suitable area (PSA) for S. frugiperda and its natural enemies can provide insights for its biocontrol and management. Therefore, based on the global distribution records and bioclimatic variables, we modeled the PSA of S. frugiperda and three egg parasitoids in China using an ensemble model (EM). We found that the prediction results of the EM were more reliable than those of a single model. The PSAs of S. frugiperda and its three egg parasitoids were mainly attributed to temperature variables. The PSA of S. frugiperda was divided into migratory and overwintering areas using the mean January 10 °C isotherm from 2018 to 2022. In the overwintering area, Trichogramma chilonis had the largest PSA overlap with S. frugiperda (94.57 %), followed by Telenomus remus (68.64 %) and Trichogramma dendrolimi (67.53 %). Telenomus remus and Tr. chilonis were the most effective egg parasitoids against S. frugiperda in the overwintering area. In the migratory area, Tr. chilonis had the largest PSA overlap with S. frugiperda (91.36 %), followed by Tr. dendrolimi (81.70 %) and Te. remus (15.23 %). Trichogramma dendrolimi would be the most effective egg parasitoid against S. frugiperda in the Yangtze River Basin and northeastern China. Trichogramma chilonis was the most effective egg parasitoid against S. frugiperda in central China. Our findings indicate that the three native egg parasitoids would be “good regulators” of S. frugiperda outbreaks in China.

Pengaruh Ekstrak daun Carica papaya terhadap Mortalitas dan Pertumbuhan Larva Spodoptera frugiperda

Invasion by Spodoptera frugiperda causing yield lossin maize production in Indonesia. Efforts to control S. frugiperda generally use synthetic pesticides, however, the use of synthetic pesticides can result in various negative impacts on the environment and health. Alternative control of S. frugiperda utilization is usingbotanical pesticides. One of the plants in Indonesia that has the potential to be developed as a botanicalpesticide is Carica papaya. C. papaya leaves extract is expected to reduce the use of synthetic pesticides in Indonesia. This research was conducted at the Agrotechnology laboratory, Universitas Perjuangan Tasikmalaya in May-September 2022. The study was arranged in a completely randomized design withonecontrol treatment, aqueous and methanol extract from C. papaya leaves 1-4%. Each treatment was repeated 4 times so that 36 trials were obtained. Each experimental unit used 10 instar2 S. frugiperda larvae. The treatment was given using the residue method on feed. The mortality value was based on treatment with 4% methanol extract with a mortality value of 75±5.77%. 3% aqueous extract had the best effect on the inhibition of growth of S. frugiperda larvae, with an average larval weight of 203 mg.

Effects of Plant Growth Regulators and Nitrogen Management on Root Lodging Resistance and Grain Yield under High-Density Maize Crops

Lodging is one of the main factors causing yield loss of maize under high-density planting conditions. Root lodging as an important lodging type has received little attention. Plant growth regulators (PGRs) and nitrogen fertilizer can coordinate the relationship between root lodging and yield. This two-year field experiment was conducted with two nitrogen levels of N225 (225 kg ha−1) and N300 (300 kg ha−1) at a high planting density (90,000 plants ha−1) during the maize growth season from 2019 to 2020. Plant growth regulator (Yuhuangjin, the mixture of 3% DTA-6 and 27% ethephon) was sprayed at the V8 stage. The results showed that PGRs significantly decreased plant height, improved root distribution and dry weight, enhanced photosynthetic rate and activities of photosynthetic carboxylase in ear leaves, and improved root bleeding sap and root activities after the silking stage. N225 combined with PGRs reduced the occurrence of root lodging and was conducive to photosynthate accumulation and root nutrient supply; it coordinated root regulation and morphological and physiological shoot functions, and played a crucial role in reducing root lodging and improving maize yield.

Recent cover crop adoption is associated with small maize and soybean yield losses in the United States.

Cover crops are gaining traction in many agricultural regions, partly driven by increased public subsidies and by private markets for ecosystem services. These payments are motivated by environmental benefits, including improved soil health, reduced erosion, and increased soil organic carbon. However, previous work based on experimental plots or crop modeling indicates cover crops may reduce crop yields. It remains unclear, though, how recent cover crop adoption has affected productivity in commercial agricultural systems. Here we perform the first large-scale, field-level analysis of observed yield impacts from cover cropping as implemented across the US Corn Belt. We use validated satellite data products at sub-field scales to analyze maize and soybean yield outcomes for over 90,000 fields in 2019-2020. Because we lack data on cover crop species or timing, we seek to quantify the yield impacts of cover cropping as currently practiced in aggregate. Using causal forests analysis, we estimate an average maize yield loss of 5.5% on fields where cover crops were used for 3 or more years, compared with fields that did not adopt cover cropping. Maize yield losses were larger on fields with better soil ratings, cooler mid-season temperatures, and lower spring rainfall. For soybeans, average yield losses were 3.5%, with larger impacts on fields with warmer June temperatures, lower spring and late-season rainfall, and, to a lesser extent, better soils. Estimated impacts are consistent with multiple mechanisms indicated by experimental and simulation-based studies, including the effects of cover crops on nitrogen dynamics, water consumption, and soil oxygen depletion. Our results suggest a need to improve cover crop management to reduce yield penalties, and a potential need to target subsidies based on likely yield impacts. Ultimately, avoiding substantial yield penalties is important for realizing widespread adoption and associated benefits for water quality, erosion, soil carbon, and greenhouse gas emissions.

Optimum total nitrogen application is required to reduce the yield loss of hybrid rice to high temperature

The grain yield and quality of rice (Oryza sativa L.) face great challenges associated with increasing temperatures, thus threatening global food security. The wheat, maize and barley yield loss magnitudes imposed by increasing temperatures reportedly interact with the nitrogen (N) application level under field conditions. However, little is known about the interactive effect between high daytime temperatures and the N supply on the rice grain yield or quality or the influence of this effect on nitrogen use efficiency in the field. In this work, two hybrid rice varieties (Liangyoupeijiu-LYPJ and IIyou602-IIY602) were grown under three N application levels (N75–75 kg ha−1, N150–150 kg ha−1, and N225–225 kg ha−1) in paddy fields in 2019 and 2020 under control and higher-temperature (HT) conditions from the heading stage to maturity. HT exposure significantly decreased the grain yields, grain filling, grain weight, grain-leaf ratio, total biomass at maturity and harvest index (HI) of the two rice varieties at all N levels across both years, while the spikelet m−2 was only affected in 2019. Moreover, the grain yield reduction caused by HT were least at N150 (57.0%) in LYPJ (68.7% and 68.8% in N75 and N225, respectively) and N75 (60.7%) in IIY602(66.0% and 64.5% in N150 and N225, respectively) on average of two years. Grain filling percentage, biomass and HI also had least decreases under N150 in LYPJ and under N75 in IIY602. Regarding the grain quality, HT exposure decreased the head rice yield and grain length, and increased chalkiness in the two varieties in both years while decreasing the amylose content and increasing the protein content in 2019 and 2020, respectively. Relatively optimal N application rates (N75 or N150 for both varieties) improved grain quality indicators such as the brown rice, head rice, grain length, chalkiness degree and amylose content under HT. After HT exposure, nonsignificant changes in N accumulation at maturity and significant reduction in N translocation and N use efficiencies for grain and biomass production were observed in both varieties. Compared to the relatively higher N applications, applying N150 to LYPJ (by 24.3%) and N75 to IIY602 (by 33.7%) induced lower N translocation reductions. Thus, our results suggest that increasing N supply cannot minimize the damage caused by HT in the realistic fields.

Laboratory and field trials reveal the potential of a gel formulation of entomopathogenic nematodes for the biological control of fall armyworm caterpillars (Spodoptera frugiperda)

The fall armyworm (FAW), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) can cause tremendous yield losses in maize. Its invasion into Africa and Asia has dramatically increased the use of insecticides in maize agro-ecosystems. Safe, effective and readily available alternatives are urgently needed. Entomopathogenic nematodes (EPN) represent a promising and sustainable option to control fall armyworm caterpillars on maize. Commonly used against soil insect pests, EPN can also be applied to control above-ground pests if formulated appropriately. We explored the possibility to control FAW by incorporating the EPN species Steinernema carpocapsae into protective formulations that can be easily applied into the whorl of maize plants, where the caterpillars mostly feed. We tested this approach in laboratory cage experiments as well as in field trials. In the laboratory, treating maize plants with a low dose of S. carpocapsae (3000 infective juveniles per plant) formulated in a carboxymethyl cellulose (CMC) gel caused 100% mortality of FAW caterpillars and substantially reduced plant damage, whereas EPN applied in water or a surfactant-polymer-formulation (SPF) caused 72% and 94% mortality, respectively. Under field conditions, one-time treatments with S. carpocapsae applied in water, SPF or CMC decreased plant damage, but only the EPN-gel formulation significantly reduced FAW infestation. As compared to control, about 40% fewer caterpillars were found on plants treated with EPN formulated in the gel. Notably, the EPN-gel formulation was as effective as a standard dose of cypermethrin, a pyrethroid insecticide commonly used against FAW, in reducing FAW infestation. Repeated applications may be needed to reduce re-infestations by FAW across a whole cropping season depending on the local maize phenology and pest dynamics. These findings demonstrate that EPN, when properly formulated, are excellent candidates for the biological control of FAW, and can be a safe and sustainable alternative to synthetic insecticides.

Integration of transcriptome and metabolome analyses reveals key lodging-resistance-related genes and metabolic pathways in maize.

Stalk lodging, or breakage of the stalk at or below the ear, is one of the vital factors causing substantial yield losses in maize (Zea mays. L). Lodging affects maize plants’ physiological and molecular processes, eventually impacting plant growth and productivity. Despite this known fact, few researchers have investigated the genetic architecture underlying lodging in maize. Herein, through integrated transcriptome, metabolome, and phenotypic analyses of stalks of three diverse hybrid cultivars (highly resistant JNK738, mildly resistant JNK728, and lowly resistant XY335) at the tasseling (10 days to silking, 10 DTS) stage, we identified key genes and metabolic pathways modulating lodging resistance in maize. Based on the RNA-Seq analysis, a total of 10093 differentially expressed genes (DEGs) were identified from the comparison of the three varieties in pairs. Additionally, key lodging resistance–related metabolic pathways were obtained by KEGG enrichment analysis, and the DEGs were found predominantly enriched in phenylpropanoid and secondary metabolites biosynthesis pathways in the L_vs._H and M_vs._H comparison groups. Moreover, K-means analysis clustered the DEGs into clear and distinct expression profiles for each cultivar, with several functional and regulatory genes involved in the cell wall assembly, lignin biosynthetic process and hormone metabolic process being identified in the special clusters related to lodging resistance. Subsequently, integrating metabolome and transcriptome analyses revealed nine key lignin-associated metabolites that showed different expression trends in the three hybrid cultivars, among which L-phenylalanine and p-coumaric acid were regarded as differentially changed metabolites (DCMs). These two DCMs belonged to phenylalanine metabolism and biosynthesis pathways and were also supported by the RNA-Seq data. Furthermore, plant hormone signal transduction pathway–related genes encoding auxin, abscisic acid, jasmonates, and salicylic acid were differentially expressed in the three comparisons of lodging resistance, indicating these DEGs were valuable potential targets for improving maize lodging resistance. Finally, comparative physiological and qRT-PCR analyses results supported our transcriptome-based findings. Our research not only provides a preliminary theoretical basis and experimental ideas for an in-depth study of the regulatory networks involved in maize lodging resistance regulation but also opens up new avenues for molecular maize stalk lodging resistance breeding.

Crop response to thermal stress without yield loss in irrigated maize and soybean in Nebraska

Thermal sensing provides rapid and accurate estimation of crop water stress through canopy temperature data. Canopy temperature is highly dependent on the transpiration rate of the leaves. It is usually assumed that any reduction in crop evapotranspiration (ET) leads to crop yield loss. As a result, an increase in canopy temperature due to a decrease in crop ET would indicate crop yield loss. This research evaluated the hypothesis that crop water stress could be detected using canopy temperature measurements (increased leaf temperature) from infrared thermometers (IRTs) before incurring crop yield loss. This would be possible in a narrow range when the photosynthesis rate (and carbon assimilation) is limited by solar radiation (energy-limiting water stress) while the leaf has abundant carbon dioxide for photosynthesis. Once photosynthesis becomes limited by carbon dioxide (carbon-dioxide-limiting water stress), then yield reduction would occur. In this field experiment, measured response variables included the integrated crop water stress index (iCWSI), ET, and crop yield for maize and soybean during the 2020 and 2021 growing seasons. The irrigation was applied at four different refill levels: rainfed (0%), deficit (50%), full (100%), and over (150%). The irrigation depth was prescribed using four different irrigation methods. The field was irrigated with a center pivot irrigation system, which was also used as a platform to mount IRT sensors. The iCWSI thresholds required for irrigation management were determined using the iCWSI dataset collected in 2020. The low, medium, and high iCWSI thresholds were 120, 150, and 180, respectively for maize and 110, 130, and 150, respectively for soybean. These thresholds should be updated with iCWSI data from future studies in this region to increase the credibility of the thresholds for irrigation management. The mean iCWSI values for consecutive days after a wetting event substantially increased with time for each irrigation level and a larger range in iCWSI values was observed among the irrigation levels after three days from a wetting event. The seasonal iCWSI for different levels were found to be negatively correlated with seasonal evapotranspiration for both years. The correlations between seasonal ET and crop yield were significant with the rainfed and deficit levels for maize (p-value < 0.001) and soybean (p-value = 0.04) in 2020. The iCWSI and yield data for the fully watered plots indicated that thermal stress was detected using the sensing system without incurring yield loss (i.e., energy-limiting water stress). The ET and yield data for 2021 indicated that reduction in seasonal crop ET did not result in yield loss which also supported the hypothesis. Future studies should investigate whether this phenomenon of detecting crop water stress in an early stage without yield loss is observed in other climates and locations.

Assessment of maize yield losses due to the effect of fall armyworm (Spodoptera frugiperda) infestation: the case of Trans-Nzoia County, Kenya

Invasive alien species have emerged as a production constraint, the most recent in Kenya being fall armyworm (FAW) (Spodoptera frugiperda). The pest incidence has resulted in farmer welfare damage by exacerbating the maize yield gap, a principal staple crop in Kenya. Through a field survey, 257 farmers were interviewed. Farmer perceived direct estimates and an iterative bidding procedure were used to assess maize yield losses. The majority of farmers (99%) were aware of fall armyworm and could correctly identify it. Moreover, most of the farmers (94%) ranked fall armyworm as the major pest for the 2018 cropping season, with more than 43% of the farmers describing the resulting yield loss as high. Yield loss estimates ranged between 0.18 to 2.7 tonnes per acre. Farmers adopted a combination of control strategies, to mitigate the effect of FAW. We conclude that FAW is a problematic pest in Kenya, based on the observed significant losses due to this pest. To inform policy on appropriate and prioritization of resources to manage FAW, yield loss estimates are key.

Android application development for identifying maize infested with fall armyworms with Tamil Nadu Agricultural University Integrated proposed pest management (TNAU IPM) capsules

Several pests and diseases wreak havoc on maize crops worldwide. Novel and rapid methods for detecting pests and diseases in real-time will make monitoring them and designing effective management measures easier. In the recent past, maize has been imperilled by fall armyworms (Spodoptera frugiperda), which have caused substantial yield losses in maize. This study aimed to create an Android mobile application via DCNN (Deep Convolutional Neural Network)-based AI pest detection system for maize producers. Everyone benefits from the deployment of these CNN models on mobile phones, especially farmers and agricultural extension professionals because it makes them more accessible. Automatic diagnosis of plant pest infestations from captured images through computer vision and artificial intelligence research is feasible for technological advancements. Therefore, early detection of maize fall armyworm (FAW) infestation and providing relevant recommendations in maize could result in intensified maize crop yields. . An Android mobile application was created to identify fall armyworm infection in maize and included the recommendations given by Tamil Nadu Agricultural University proposed Integrated Pest Management (TNAU IPM ) capsules in the mobile app on as to how to deal with such a problem. Digital and novel technology was chosen to address these issues in maize. Deep convolutional neural networks (DCNNs) and transfer learning have recently moved into the realm of just-in-time crop pest infestation detection, following their successful use in a variety of fields. The algorithm accurately detects FAW (S. frugiperda) infected areas on maize with 98.47% training accuracy and 93.47% validation accuracy.

Nutritional management and maize variety combination effectively control Striga asiatica in southern Africa

Maize (Zea mays L.) is an important staple food crop in sub-Saharan Africa (SSA) and contributes significantly to food security. Due to Striga, maize yield loss is estimated between 20 and 80% forcing some farmers to abandon their land therefore threatening food security. Many strategies have been applied to combat Striga infested fields to improve maize yields but alternative feasible approaches are still required. This study aimed at determining effects of phosphorus (P) and maize variety on Striga asiatica germination and attachment. A factorial experiment of eight P levels (0, 10, 20, 30, 40, 50, 60 and 70 kg ha−1), six maize varieties and Striga (inoculated and non-inoculated) in a 4 × 24 α-lattice design with three replications was set in a glasshouse at the University of Zimbabwe. A similar experiment was set under laboratory conditions using agar gel plates to determine S. asiatica germination using a complete randomized design with three replications. Adding P (at 40 kg ha−1) to soil infected with Striga, significantly (p < 0.05) reduced Striga counts and haustorial root attachments in all varieties with CV4 and R201 supporting lowest numbers. P also significantly (p < 0.05) improved plant height, chlorophyll content, leaf, cob, total biomasses and grain yield across all maize genotypes. Cultivar CV4 produced the highest grain yield under Striga attack. Furthermore, cultivars CV4 and CV1 had significantly (p < 0.05) lowest Striga seed maximum germination distance and percentages at zero P. Application of P reduced Striga germination, attachments and emergence in all varieties and increased tolerance of maize varieties.

Optimizing plastic mulching improves the growth and increases grain yield and water use efficiency of spring maize in dryland of the Loess Plateau in China

Transparent plastic film mulching (PFM) with flat cropping cultivation has been widely applied to grow maize (Zea mays L.) in dryland agricultural production areas of the Loess Plateau in China. However, with global warming-induced gradual increase in soil temperature, film-mulched spring maize experiences premature senescence and yield loss. In this study, a new form of mulching strategy involving dual mulching of transparent plastic film with whole maize stalks in a flat plot was established to improve growth and increase water use efficiency (WUE), precipitation use efficiency (PUE), and spring maize yield. The field experiment was conducted in 20 182 019, and 2020 on a conventional flat plot without mulching (CK), a flat plot with single transparent PFM, and a flat plot of transparent film mulching with whole maize stalks (PFM+ST) in the dryland of the Loess Plateau in China, to quantify the effects of different treatments on soil hydrothermal conditions, maize phenology, plant growth dynamics, WUE, PUE, and maize yield. Results demonstrated that soil water storage (SWS) at 0–100 cm soil layer in PFM and PFM+ST were significantly superior to those in CK, but SWS did not significantly differ between PFM and PFM+ST. Soil temperature under PFM+ST at 0–25 cm soil layer decreased by 1.2 ℃ compared with that under PFM during growth, especially in early growing seasons (20–60 days after sowing [DAS]). PFM+ST extended vegetative and reproductive growth periods by 1–2 and 6–7 days compared with those in PFM, respectively. In later growth period (80–120 DAS), PFM+ST increased the root dry matter weight, SPAD, and LAI and significantly increased the aboveground dry matter accumulation. PFM+ST significantly increased the 100-kernel dry weight, grain yield, WUE, and PUE. PFM+ST had 3-year average grain yields of 10.82% and 36.48% greater than PFM and CK, respectively. The corresponding WUE and in 0–200 cm soil layer improved by 12.55% and 39.84%, and PUE improved by 10.82% and 36.48%, respectively. With global warming, applying PFM+ST cultivation practice effectively extended growth period and increased mulching spring maize yield and WUE in the study site.

Evaluation of Resistance of Eleven Maize Races (Zea mays L.) to the Red Spider Mite (Tetranychus merganser, Boudreaux).

At least 59 maize races (Zea mays L.) have been registered in Mexico. The feeding damage caused by insects and mites to maize crops generates up to ~30% of maize yield losses. Spider-mite-resistant plants are needed. The red spider mite, Tetranychus merganser Boudreaux (Acari: Tetranychidae), is distributed in the United States, China, Mexico, and Thailand. It is considered a potential pest in Mexican agriculture. The aim of this study was to evaluate the resistance mechanisms (antixenosis and antibiosis) of 11 native maize populations, representative of each race of maize grown in Tamaulipas, Mexico, to T. merganser under laboratory conditions. The aim was also to obtain information on the chemical composition and some morphological characteristics of these maize races and to identify resistant maize races for incorporation into a breeding program. Antixenosis was assessed by non-preference for oviposition and feeding. Antibiosis was measured by growth rate (ri). The presence of secondary metabolites in the 11 maize races were different. In the 11 maize races, quantitative analysis of total phenol concentration, total flavonoid concentration, and antioxidant capacity were significantly different. The multivariate analysis of variance showed that there is evidence of antixenosis noted by maize race differences in egg laying and percentage feeding damage but not of antibiosis noted by growth rate. Red spider mites laid significantly more eggs on the Celaya (24 h: 25.67 ± 17.04, 48 h: 42.67 ± 26.86, 72 h: 49.33 ± 28.54) race than on Raton (24 h: 7.00 ± 5.00, 48 h: 12.67 ± 8.02, 72 h: 14.67 ± 9.29) and Elotes Occidentales × Tuxpeño (24 h: 9.67 ± 5.85, 48 h: 15.33 ± 10.69, 72 h: 17.67 ± 10.97) races. However, the growth rate and mortality of T. merganser in the 11 corn races were similar. The Vandeño (24 h: 11.67 ± 2.89, 48 h: 27.67 ± 7.64, 72 h: 30.00 ± 18.03) and Tabloncillo × Tuxpeño (24 h: 18.33 ± 7.64, 48 h: 25.00 ± 8.66, 72 h: 25.00 ± 8.66) races were the most resistant to red spider mite damage, whereas the most susceptible race was Celaya (24 h: 26.67 ± 15.28, 48 h: 48.33 ± 29.30, 72 h: 65.00 ± 30.00). Further analysis by PCA at 24, 48, and 72 h found the Celaya race positively correlated to growth rate and oviposition of T. merganser and to a lesser extent with the percentage of feeding damage, suggesting that the Celaya race was most susceptible to T. merganser. At 24 h, the Vandeño race was most resistant, given a negative correlation to growth rate and oviposition by T. merganser. The PCA at 48 and 72 h noted the Elotes Occidentales × Tuxpeño race was most resistant to red spider mite, with negative relationships to growth rate and oviposition and, to a lesser extent, to feeding damage. This resistance is due to the differences in both its morphological characteristics and the secondary metabolites present in their leaves.

Developing stage-specific drought vulnerability curves for maize: The case study of the Po River basin

Drought and water stress negatively affect many human activities, with agriculture playing a crucial role in ensuring food security. The drought vulnerability assessment of agricultural systems has been widely investigated in the past and the relationship between drought hazard and losses has been traditionally expressed through vulnerability curves. This study develops maize drought vulnerability curves tailored to the context of the Po River Basin (Northern Italy) which is the largest Italian agricultural area and accounts for 35% of national crop production. The curves express the relationship between crop water stress and maize yield losses. Four crop growth stages are considered (establishment, vegetative, flowering and yield formation) since the sensitivity of maize to water stress is strictly related with the plant growth stage. In addition, the influence of soil texture on the maize response to water stress is investigated. The Agricultural Production System sIMulator (APSIM) is used to simulate the crop yield and the water stress. APSIM is calibrated on observed yield and the model skill in reproducing maize yield is satisfactorily verified (Pearson correlation coefficient equals to 0.87). Flowering is the most sensitive stage to water deficit independently from the soil texture, while the yield formation phase is most sensitive to water stress than the vegetative in the case of Loam soils. The achieved results suggest the importance of the use of appropriate irrigation strategies. Water should be provided to maize in case of a water stress during the flowering phase to avoid irreparable yield losses.

Detect and attribute the extreme maize yield losses based on spatio-temporal deep learning

Providing accurate crop yield estimations at large spatial scales and understanding yield losses under extreme climate stress is an urgent challenge for sustaining global food security. While the data-driven deep learning approach has shown great capacity in predicting yield patterns, its capacity to detect and attribute the impacts of climatic extremes on yields remains unknown. In this study, we developed a deep neural network based multi-task learning framework to estimate variations of maize yield at the county level over the US Corn Belt from 2006 to 2018, with a special focus on the extreme yield loss in 2012. We found that our deep learning model hindcasted the yield variations with good accuracy for 2006-2018 (R2 = 0.81) and well reproduced the extreme yield anomalies in 2012 (R2 = 0.79). Further attribution analysis indicated that extreme heat stress was the major cause for yield loss, contributing to 72.5% of the yield loss, followed by anomalies of vapor pressure deficit (17.6%) and precipitation (10.8%). Our deep learning model was also able to estimate the accumulated impact of climatic factors on maize yield and identify that the silking phase was the most critical stage shaping the yield response to extreme climate stress in 2012. Our results provide a new framework of spatio-temporal deep learning to assess and attribute the crop yield response to climate variations in the data rich era.

Invasion of Fall armyworm [Spodoptera frugiperda (JE Smith, 1797) (Lepidoptera: Noctuidae)] (JE Smith ,1797) (Lepidoptera: Noctuidanead) Management Strategies in Maize Fields of Nepal

The fall armyworm [Spodoptera frugiperda, (JE Smith, 1797) (Lepidoptera: Noctuidae)] is a polyphagous pest native to tropical and subtropical regions of America. After it was detected for the first time in Nepal in the Nawalpur area on 9th May 2019, it has become a major threat in maize fields even though it has over 80 host species to proceed its life cycle. Due to its migratory nature, FAW moth can travel up to 500 km before oviposition, and infestation of its larva has resulted in vast devastation of the vegetative as well as reproductive parts of plants causing significant yield loss in maize. A mature larva possesses a dark head with an upside-down pale Y-shaped marking on the head area and black four spots that are arranged in a square on the second last body segment. This paper audits the executive choices (avoidance, observing, push-pull, cultural, biological, organic, chemical, and integrated techniques to incorporate in FAW susceptible areas) that apply to smallholder farmers who do not have the monetary asset to buy compound pesticides and other costly control instruments. For the majority of Nepalese farmers with low resources and small landholding, push-pull technology is beneficial and applicable. Botanicals that have bioactive chemical compounds, insecticidal, pest repellent properties are environment-friendly and degradable, readily available in tropical and subtropical regions of Nepal. The assessment of the efficacy of implemented management practices against FAW has revealed that implementation of more than one method of management practices showed the least percentage of infestation as compared to the individual method.