Leaf Stage Research Articles

Cloning and functional analysis of ZmMADS42 gene in maize

ABSTRACT Maize (Zea mays L.) is the most important cereal crop in the world. Flowering period and photoperiod play important roles in the reproductive development of maize. This study, investigated ZmMADS42, a gene that is highly expressed in the shoot apical meristem. Agrobacterium infection was used to successfully obtain overexpressed ZmMADS42 plants. Fluorescence quantitative PCR revealed that the expression of the ZmMADS42 gene in the shoot apical meristem of transgenic plants was 2.8 times higher than that of the wild-type(WT). In addition, the expression of the ZmMADS42 gene in the endosperm was 2.4 times higher than that in the wild-type. The seed width of the T2 generation increased by 5.35%, whereas the seed length decreased by 7.78% compared with that of the wild-type. Dissection of the shoot tips of transgenic and wild-type plants from the 7-leaf stage to the 9-leaf stage revealed that the transgenic plants entered the differentiation stage earlier and exhibited more tassel meristems during their vegetative growth period. The mature transgenic plants were approximately 20 cm shorter in height and had a lower panicle position than the wild-type plants. Comparing the flowering period, the tasseling, powdering, and silking stages of the transgenic plants occurred 10 days earlier than those of the wild-type plants. The results showed that the ZmMADS42 gene played a significant role in regulating the flowering period and plant height of maize.

Variations in grain yield and nutrient status of different maize cultivars by application of zinc sulfate.

Although maize is sensitive to zinc (Zn) deficiencies, the responses of maize cultivars to the foliar application of Zn sulfate (ZnSO4) may vary significantly. Here, we quantified the responses of grain yields and nitrogen (N), phosphorus (P), and potassium (K) absorption to ZnSO4 using 22 modern maize cultivars. The results revealed that 40.9% of the cultivars were not affected by foliar ZnSO4, whereas only 45.5% of the cultivars responded positively to ZnSO4, which was evidenced by increased grain numbers and shortened bald tip lengths. The impact of Zn fertilizer might be manifested in the dry biomass, from the 8-leaf stage (BBCH 18). For Zn-deficiency resistant cultivars, the foliar application of ZnSO4 enhanced N accumulation by 44.1%, while it reduced P and K absorption by 13.6% and 23.7%, respectively. For Zn-deficiency sensitive maize cultivars, foliar applied ZnSO4 improved the accumulation of N and K by 27.3% and 25.0%, respectively; however, it lowered their utilization efficiency. Hence, determining the optimized application of Zn fertilizer, while avoiding Zn toxicity, should not be based solely on the level of Zn deficiency in the soil, but also, take into consideration the sensitivity of some cultivars to Zn, Furthermore, the supplementation of Zn-deficiency sensitive maize cultivars with N and K is key to maximizing the benefits of Zn fertilization.

Shading and waterlogging interactions exacerbate summer maize yield losses by reducing assimilate accumulation and remobilization processes

Persistent overcast rain was an essential limiting factor for summer maize production, of which immediate impact was the dual pressure of waterlogging and shading. However, the mechanism of independent and combined effects of waterlogging and shading induced maize yield losses are rarely studied, especially at different growth stages. Denghai 605 (DH605) was selected to be subjected shading, waterlogging, and their combined stress at the 3rd leaf stage (V3), the 6th leaf stage (V6), and tasseling stage (VT). Results showed that shading, waterlogging and their combination significantly limited the expansion of leaf area, and decreased leaf net photosynthetic rate (Pn) and net assimilation rate (NAR), thus reducing the crop growth rate (CGR) and biomass accumulation. At the same time, compared to control, the process of lignin synthesis was inhibited under stressed treatment, resulting in reduced stem mechanical strength and a poor development of the vascular system, of which change significantly reduced efficiency of assimilate remobilization to the ear and ultimately grain yield. The most significant effects of waterlogging and combined stresses on yield were occurred at V3 stage, followed by the V6 and VT stages. The most significant effects of shading were occurred at VT stage, followed by the V6 and V3 stages. Moreover, the compound stress exacerbated the damage brought about by a single stress. It is predicted that climate change will increase the frequency of abiotic stress assemblages, and the results of these findings provide some direction for further research on maize breeding in summer maize under continuous rainy conditions in the future.

Productivity of Dry Direct Seeded Rice as Influenced by Herbicide Combinations

A field experiment was conducted during Kharif, 2022, in Institute of Rice Research, Rajendranagar, Hyderabad in Telangana state, India. Fourteen weed management practices were evaluated in a randomized complete block design, replicated thrice. Weed management in Dry DSR can be done by adopting mechanical/ Hand weeding at 20, 40, 60 DAS under labour available conditions. Under labour scarcity conditions PE application of Pendimethalin 38.4% + Pyrazosulfuron ethyl 0.85% ZC 900 + 20 g/ha (Ready mix) followed by Metsulfuron Methyl 10% + Chlorimuron ethyl 10% WP 4 g/ha + Cyhalofop Butyl 10% EC 75g/ha (Tank mix) PoE weed followed by mechanical weeding at 40-45 DAS is the best option. Other suitable Pre emergence herbicides that can be used are Pyrazosulfuron ethyl 10% WP 20 g/ha, Pendimethalin 38.4% + Pyrazosulfuron ethyl 0.85% ZC 900 + 20 g/ha (Ready mix) and Pendimethalin 38.7 % CS 677.25 g/ha. Post emergence application of Triafamone 20% + Ethoxysulfuron l0% WG 44+22.5 g/ha (Ready mix) and Penoxsulam 1.02 % + Cyhalofop-butyl 5.1% OD 135 g/ha (Ready mix) at 2-4 weed leaf stage.

The influence of metal nanocarboxylates on the nitrogen-fixing activity of symbiotic soybean systems grown under field conditions

Background. Numerous scientific and industrial studies have proven the high effectiveness of using micronutrients in nanoscale form in agricultural crop cultivation technologies. Among them, special attention is drawn to soybeans, which hold a leading position in terms of sown areas among other leguminous crops in the country. They can provide up to 70 % of their own nitrogen needs through the fixation of its molecular form from the atmosphere in symbiosis with Bradyrhizobium japonicum nodulating bacteria. New methods of molecular biology, biotechnology, and genetic engineering, along with classical methods of microbiology, plant physiology, genetics, and agrochemistry, allow for addressing both fundamental questions regarding the characteristics of formation and functioning of legume-rhizobial systems, and practical approaches to correcting the interactions between symbiotic partners with the aim of creating highly effective symbioses. Therefore, research aimed at significant increasing the current level of biological nitrogen fixation and adapting symbiotic systems to negative environmental factors is currently relevant. The use of nanotechnology, in particular, the study of the effect of iron, germanium, and cobalt nanocarboxylates on the formation and functioning of the soybean-rhizobial symbiosis under field conditions in combination with seed inoculation with rhizobial bacteria may be promising. Materials and Methods. The objects of the investigation were symbiotic systems created with the participation of the Almaz variety of soybean and the Bradyrhizobium japonicum B1-20 rhizobacteria, and with the introduction of nanocarboxylates of iron (Fe), germanium (Ge) and cobalt (Co) into their cultivation medium. Physiological, microbiological, biochemical, and statistical research methods were used. Results. It was found that under field conditions, before the pod formation stage, the vegetative mass of soybean plants inoculated with rhizobial bacteria with the introduction of nanoparticles of carboxylates of iron, germanium, or cobalt into their cultivation medium was at the level of control plants or slightly exceeded them. It has been shown that under the effects of chelated micronutrients, the number of root nodules increased compared to control plants during the flowering and pod formation stages, and their mass was greater from the three trifoliate leaf stage, which ensured efficient functioning of the legume-rhizobial symbiosis. It has been noted that the used metal nanocarboxylates promote active functioning of the symbiotic apparatus in soybean plants, as an increase in nitrogen-fixing activity was observed at the stages of three trifoliate leaf development and flowering, ranging from 26–70 % depending on the microelement used. Conclusions. During field cultivation of soybeans, the effectiveness of pre-sowing seed inoculation with Bradyrhizobium japonicum B1-20 rhizobia was demonstrated through the introduction of iron, germanium, or cobalt nanocarboxylates into their cultivation medium. This opens up opportunities for increasing the efficiency of symbiotic systems of soybeans.

Влияние на вегетационния хербицид Енвоке върху някои структурни елементи на продуктивността и добива от памук (Gossypium hirsutum L.)

Weeding during the growing season of cotton suppresses and slows down the growth and development of plants, and can lead to a significant reduction in yield and deterioration of fiber quality. The aim of this research was to study the effect of vegetation applied herbicide Envoke on the yield of cotton and some structural elements of productivity such as percent of boll opening and boll weight, under different agro-meteorological conditions. The research was conducted during the period 2020-2022 in the experimental field of the Field Crops Institute in Chirpan. In a three-factor field experiment, the effect of vegetation applied herbicide Envoke, containing 75% trifloxysulforon-sodium, was tested on two cotton varieties. Factor A included the three years of study. Factor B included the cultivars Chirpan-539 and Helius. Factor C included the herbicide Envoke applied in 3 doses - 10 g.ha-1, 15 g.ha-1 and 20 g.ha-1, once and twice during the 4-5 leaf and budding stages of cotton. It was established that when treated with the herbicide Envoke, the highest yield was obtained with the single treatment in the budding phase at a dose of 20 g.ha-1 for the cultivar Chirpan-539 and at a dose of 15 g.ha-1 for the cultivar Helius. Technologically valuable were found all variants with the herbicide Envoke in the cultivar Chirpan-539 and the variants in doses of 15 g.ha-1 and 20 g.ha-1 in the cultivar Helius. These options combined high yield values and high stability of this indicator in different years. The untreated controls in both cultivars were the only ones that received negative scores. This was due to the high number of weeds and self-sown sunflower (Helianthus annuus L.) plants. The vegetation herbicide Envoke, applied in three doses, once and twice during the 4-5 leaf and budding stages of cotton, had little influence on the percentage of boll opening and did not affect the boll weight at the treated variants of the two cotton cultivars - Chirpan-539 and Helius.

Detrimental impacts of concomitant application of cadmium and pesticides are ameliorated by 24-epibrassinolide through alteration in oxidative status and CYP genes expression in Zea mays L.

The ameliorative impact of 24-epibrassinolide (EBL) was assessed under toxicity of cadmium (Cd) and three different pesticides including diazinon (DZ), imidacloprid (IMI), and chlorpyrifos (CPS) in maize plants. Maize seeds were pre-treated with 0.01 μM of EBL and grown in soil contaminated with 100 μM Cd for one month. Then, at five fully expanded leaf stage, plants received DZ, IMI, and CPS pesticides separately by foliar spray and were harvested five days later. The EBL seed primed plants, grown in soil contaminated with Cd and exposed to pesticides, exhibited higher deleterious photosynthesis (Pn) and stomatal conductivity (Gs) compared to un-EBL-treated plants. A considerable decrease was observed in the pesticide's residue and Cd, MDA and H2O2 contents of EBL + Cd + Pesticide treated plants compared to the Cd + Pesticide groups plants. Higher phenol, flavonoid and protein contents, as well as increment in SOD, CAT, POD, APX, PAL, GST, and GR enzymes activity were detected in EBL + Cd + Pesticide groups compared to the plants imposed with Cd + Pesticides. The expression analyses of four CYP family members including CYP71C1, CYP71C3v2, CYP72A5, and CYP81A9 revealed downregulation under Cd and Cd + pesticides treatments, while EBL seed priming highly induced transcript abundance of CYP71C1 (EBL + Cd + IMI); CYP71C3v2 (EBL + Cd + DZ & EBL + Cd + IMI) and CYP81A9 (EBL + Cd + DZ & EBL + Cd + CPS), specifically. The higher mRNA accumulation of CYP72A5 gene was exhibited under all three different EBL + Cd + pesticides treatments. The 24-epibrassinolide alleviates the adverse impacts of Cd and pesticides via the activation of enzymatic and non-enzymatic components to eliminate ROS through the up-regulation of CYP genes. This facilitates conjugation of glutathione to pesticides residue, leading to their rapid transportation into the vacuole or out of the membrane.

The complex stress of waterlogging and high temperature accelerated maize leaf senescence and decreased photosynthetic performance at different growth stages

AbstractThe greenhouse effect caused by global warming was becoming more and more obvious, resulting in increased frequency of high temperature and high humidity, which significantly affected maize productivity. However, it was poorly understood how the interactions of high temperature and high humidity affected leaf senescence, photosynthetic performance and yield of summer maize. Three stress treatments including (a) high temperature stress (T), (b) waterlogging stress (W) and (c) complex stress (T‐W) were set at the third leaf stage (V3), the sixth leaf stage (V6) and the tasselling stage (VT) in 2019–2020 to explore the influence mechanism of complex stress. Each stress treatment period lasted 6 days. Non‐stressed plants served as control. Yield, antioxidant enzyme activity, photosynthetic characteristics, and dry matter accumulation were determined. Our study found that the activity of antioxidant enzymes was significantly decreased, while malonyldialdehyde (MDA) accumulation was increased under each stress treatment. As a result, the photosynthetic characteristics were impaired, manifested in a significant decrease in net photosynthetic rate (Pn), enzyme activities of phosphoenolpyruvate carboxylase (PEPCase) and ribulose diphosphate carboxylase (RUBPCase). The decrease in photosynthetic intensity affected by each stress treatment led to a significant decrease in total dry matter accumulation and grain yield. The most significant effects of waterlogging and combined stresses on yield occurred at the V3 stage, followed by the V6 and VT stages. However, the most significant effects of high temperature occurred at the VT stage, followed by the V6 and V3 stages. Moreover, the compound stress exacerbated damage to leaf senescence and photosynthetic properties of summer maize compared to the single stress of high temperature or waterlogging.

Prohexadione-Calcium Mitigates the Overgrowth of Corn Seedlings

In the temperate climate of South Korea, specific corn varieties are cultivated using plug trays. The cultivation process is initiated from February to March within greenhouse facilities, maintaining a temperature below 10 degrees Celsius. Following this, in April, seedlings are transplanted to enable an exceptionally early harvest for increased profitability. However, the subsequent elevation in indoor temperatures leads to seedling overgrowth. This study explores the effectiveness of three plant growth regulators—paclobutrazol, prohexadione-calcium, and diniconazole–on super sweet corn seedlings. Significantly, the application of prohexadione-calcium at 2 ppm during the first leaf stage substantially reduces seedling height and impedes the growth of both the first and second internodes. This impact extends to leaf-related traits, manifesting reductions in the area, length, and width of the third leaf. Furthermore, prohexadione-calcium induces a significant decrease in both fresh and dried shoot weight, while simultaneously augmenting root weight. This alteration results in a noteworthy shift in the root–shoot ratio, particularly at 2 ppm. Subsequent experiments have identified the optimal concentration of prohexadione-calcium at 15 ppm, effectively mitigating overgrowth in both hybrid and inbred corn varieties. These findings provide essential insights for practitioners seeking to efficiently manage corn seedling overgrowth. The study contributes to understanding the retardant effect of prohexadione-calcium on various morphological traits, offering practical applications for optimizing plant growth regulator concentrations in corn cultivation strategies.

Herbicide Bioassay Using a Multi-Well Plate and Plant Spectral Image Analysis.

A spectral image analysis has the potential to replace traditional approaches for assessing plant responses to different types of stresses, including herbicides, through non-destructive and high-throughput screening (HTS). Therefore, this study was conducted to develop a rapid bioassay method using a multi-well plate and spectral image analysis for the diagnosis of herbicide activity and modes of action. Crabgrass (Digitaria ciliaris), as a model weed, was cultivated in multi-well plates and subsequently treated with six herbicides (paraquat, tiafenacil, penoxsulam, isoxaflutole, glufosinate, and glyphosate) with different modes of action when the crabgrass reached the 1-leaf stage, using only a quarter of the recommended dose. To detect the plant's response to herbicides, plant spectral images were acquired after herbicide treatment using RGB, infrared (IR) thermal, and chlorophyll fluorescence (CF) sensors and analyzed for diagnosing herbicide efficacy and modes of action. A principal component analysis (PCA), using all spectral data, successfully distinguished herbicides and clustered depending on their modes of action. The performed experiments showed that the multi-well plate assay combined with a spectral image analysis can be successfully applied for herbicide bioassays. In addition, the use of spectral image sensors, especially CF images, would facilitate HTS by enabling the rapid observation of herbicide responses at as early as 3 h after herbicide treatment.

Response of conventional sunflower cultivars to drift rates of synthetic auxin herbicides.

The agrochemical industry has launched several new synthetic auxin herbicides in rice to combat increasing numbers of herbicide resistant weeds to other modes of action. Excessive or inappropriate use of these herbicides has resulted in unintended consequences near the sites of application, such as herbicide drift. This study was conducted to determine the impact of drift of quinclorac and florpyrauxifen-benzyl+penoxsulam (FBP) on the yield and yield components of two sunflower cultivars. In a growth chamber experiment, quinclorac and FBP were applied to 2-4 true leaf stages at rates ranging from 2.93 to 93.75 and from 0.51 to 16.25 g ai ha-1, respectively. Nonlinear regression analyses indicated that the cultivar Bosfora was more sensitive to quinclorac and FBP than the cultivar Tunca. In field experiments, these sunflower cultivars were treated with drift rates of quinclorac (<375 g ai ha-1) and FBP (<65 g ai ha-1) when they were at the 8-10 true leaf stage. Quinclorac and FBP drift rates resulted in up to 52-61% and 85-100% injury and 82-88% and 100% yield loss, respectively. Crop injury and yield data clearly showed that cultivar Bosfora was more sensitive to FBP and quinclorac rates than cultivar Tunca, and both cultivars were more sensitive to FBP than quinclorac. In our work, we also found that plant height reduction caused by quinclorac at early growth stages may be a valuable indicator to evaluate crop injury and yield loss.

The Impact of Accumulating Herbage Masses in Autumn on Perennial Ryegrass Sward Characteristics

Autumn grazing management aims to accumulate herbage for defoliation prior to a decrease in growth rates for the extension of the grazing season. The current study investigated the impact of building different target herbage masses (THMs) in autumn and imposing one of three different defoliation dates (DDs) between mid-October and late November on light transmitted to the base of the sward, free leaf lamina (FLL), leaf stage and internode elongation. Four THMs (low, medium, high and very high) and three DDs (DD1—15 October, DD2—7 November and DD3—21 November) were assigned to a 4 × 3 split plot design over two years. Light transmitted to the base of the sward was greatest in the low THM and decreased in all other THMs. Internode elongation increased in tillers in the medium to the very high THMs. Defoliation of the medium, high and, in particular, the very high THMs earlier in autumn reduced the effect of decreased light transmission on internode elongation. This study highlights that, as light transmitted to the base of the sward decreases, internode elongation increases, and this could negatively impact sward structure.

Maize plant detection using UAV-based RGB imaging and YOLOv5.

In recent years, computer vision (CV) has made enormous progress and is providing great possibilities in analyzing images for object detection, especially with the application of machine learning (ML). Unmanned Aerial Vehicle (UAV) based high-resolution images allow to apply CV and ML methods for the detection of plants or their organs of interest. Thus, this study presents a practical workflow based on the You Only Look Once version 5 (YOLOv5) and UAV images to detect maize plants for counting their numbers in contrasting development stages, including the application of a semi-auto-labeling method based on the Segment Anything Model (SAM) to reduce the burden of labeling. Results showed that the trained model achieved a mean average precision (mAP@0.5) of 0.828 and 0.863 for the 3-leaf stage and 7-leaf stage, respectively. YOLOv5 achieved the best performance under the conditions of overgrown weeds, leaf occlusion, and blurry images, suggesting that YOLOv5 plays a practical role in obtaining excellent performance under realistic field conditions. Furthermore, introducing image-rotation augmentation and low noise weight enhanced model accuracy, with an increase of 0.024 and 0.016 mAP@0.5, respectively, compared to the original model of the 3-leaf stage. This work provides a practical reference for applying lightweight ML and deep learning methods to UAV images for automated object detection and characterization of plant growth under realistic environments.

Understanding the risks of antibiotics released from livestock on agricultural productivity: Evidence from mung bean [Vigna radiata (L.) Wilczek] pot experiment

Antibiotics of veterinary origin are generally released to agricultural fields via grazing animals or manure. Antibiotics can also be delivered to agricultural lands by reclaimed wastewater irrigation as they have been found in both raw and processed sewage effluents. Possible effects of antibiotics on crop plants, particularly of mung bean (Vigna radiata cv. NM-11) were investigated in the present study. A pot experiment comprising four different treatments (0, 1 µg L-1, 5 µg L-1, and 10 µg L-1) of amoxicillin was carried out under natural atmospheric conditions. Five applications each of 200 mL of different concentrations of amoxicillin and one concentration of distilled water (control) were administered at two leaf stage onwards to the respective groups of mung bean plants. The effects of amoxicillin were assessed on the post-germination traits (agronomic parameters) of mung bean during ontogenesis and at the time of full development. The antibiotic adversely affected the plant agronomic traits which were determined twice at four-week intervals. The amoxicillin, even in small concentrations, adversely affected the growth as well as yield parameters of mung bean plants. Moreover, varying concentrations of amoxicillin used in the experiment also declined chlorophyll biosynthesis especially at the later stages of plant development.

Эффективность новых гербицидов на посевах кукурузы в условиях Западного Предкавказья

When studying the effectiveness of using promising herbicides on crops of corn hybrids in the central zone of the Krasnodar Territory, it was found that corn crops are predominantly contaminated with dicotyledonous weeds such as Theophrastus rope, upturned acorn grass, ragwort, white pigweed, self-seeded poppy, and shepherd’s purse. Cereal (monocot) weeds are represented by blue bristle grass, green bristle grass and chicken millet. Perennial weeds include by field bindweed. The most effective herbicide is Adengo in the 1–2 leaf stage, giving a yield increase of 56.1 c/ha. At the same time, corn hybrids in the mid-early group yielded 91.5 c/ha and those in the mid-ripening group 77.1 c/ha. To obtain a corn yield of 100 c/ha, it is necessary to apply the herbicide Adengo (0.5 l/ha) at the stage of 1–2 leaves in the technology of cultivation of its hybrids DKS3969, DKS3 and DKS3789

Pan-Genomic Analysis Identifies the Chinese Strain as a New Subspecies of Xanthomonas fragariae.

Xanthomonas fragariae is classified as a quarantine pathogen by the European and Mediterranean Plant Protection Organization. It commonly induces typical angular leaf spot (ALS) symptoms in strawberry leaves. X. fragariae strains from China (YL19, SHAQP01, and YLX21) exhibit ALS symptoms in leaves and more severe symptoms of dry cavity rot in strawberry crowns. Conversely, strains from other countries do not cause severe dry cavity rot symptoms in strawberries. After employing multilocus sequence analysis (MLSA), average nucleotide identity (ANI), and amino acid identity (AAI), we determined that Chinese strains of X. fragariae are genetically distinct from other strains and can be considered a new subspecies. Subsequent analysis of 63 X. fragariae genomes published at NCBI using IPGA and EDGAR3.0 revealed the pan-genomic profile, with 1,680 shared genes present in all 63 strains, including 71 virulence-related genes. Additionally, we identified 123 genes exclusive to all the Chinese strains, encompassing 12 virulence-related genes. The qRT-PCR analysis demonstrated that the expression of XopD, XopG1, CE8, GT2, and GH121 out of 12 virulence-related genes of Chinese strains (YL19) exhibited a constant increase in the early stages (6, 24, 54, and 96 hours postinoculation [hpi]) of strawberry leaf infected by YL19. So, the presence of XopD, XopG1, CE8, GT2, and GH121 in Chinese strains may play important roles in the early infection process of Chinese strains. These findings offer novel insights into comprehending the population structure and variation in the pathogenic capacity of X. fragariae.

Oxyfluorfen-resistant rice tolerance and weed control when using oxyfluorfen

Abstract Herbicide-resistant barnyardgrass and weedy rice control, without crop injury, is a challenge for rice producers in the United States. Herbicides not initially labeled for rice, such as oxyfluorfen, are now being evaluated as new tools for weed control. The ROXY® trait allows for the use of oxyfluorfen in rice for weed control preemergence and postemergence. Experiments were initiated in 2021 and 2022 to evaluate (1) the effectiveness of preemergence- and postemergence-applied oxyfluorfen on barnyardgrass and weedy rice, (2) the sensitivity of oxyfluorfen-resistant rice to oxyfluorfen as a function of application timing, and (3) the influence of soil moisture on oxyfluorfen-resistant rice sensitivity to oxyfluorfen. In the field, a rate response was observed for oxyfluorfen applied to weedy rice when averaged over application timings of 1-leaf, 2-leaf, 3-leaf, and tillering, with oxyfluorfen at 1,680 g ai ha−1 resulting in 81% and 72% control 7 d after application (DAA) in 2021 and 2022, respectively. Under greenhouse conditions, barnyardgrass and weedy rice control averaged by the rate of oxyfluorfen was ≥85 and ≥70%, respectfully, 7 DAA for the 1-, 2-, and 3-leaf rice growth stage timings. Preemergence applications of oxyfluorfen under 100% soil saturation resulted in 75% injury to oxyfluorfen-resistant rice, greater than all other soil moisture at 7 DAA. All postemergence applications of oxyfluorfen resulted in 63% to 70% injury to oxyfluorfen-resistant rice at 7 DAA, regardless of soil moisture. Barnyardgrass and weedy rice control with oxyfluorfen is achieved with timely applications; however, injury to oxyfluorfen-resistant rice is likely.

Water-seeded rice response to pendimethalin applied at different rates and timings

Abstract Currently, a limited number of herbicides is available to treat water-seeded rice in California, with widespread resistance to most of those herbicides. Because no resistant grasses showed resistance to pendimethalin, a series of studies were conducted to evaluate water-seeded rice response to pendimethalin. In a field study conducted at the Rice Experiment Station at Biggs, California, in 2020 and 2021, three pendimethalin formulations, a granule (GR), emulsifiable concentrate (EC), and capsule suspension (CS), were applied at 1.1, 2.3, and 3.4 kg ai ha−1 rates, and at 5, 10, and 15 d after seeding onto water-seeded rice. In addition, a greenhouse study was conducted to examine the response of five common California rice cultivars to GR and CS formulation applications. Echinochloa control levels were reduced at 15 d after seeding after use of EC and CS formulations compared with earlier timings. In both years, rice grain yields were increased by 3,014 kg ha−1 after application of pendimethalin at 3.4 kg ai ha−1 when applied at 15 d after seeding compared with 5 and 10 d after seeding, and similar to 1.1 kg ai ha−1 applications. The GR and CS were safer formulations based on a reduction in injury and an increase in grain yields compared to the EC formulation. Differences in seedling vigor across cultivars appeared to incur an advantage after a pendimethalin application. However, most cultivars evaluated for stand reduction and dry biomass demonstrated tolerance to GR and CS formulation applications only after rice reached the 3-leaf stage. In contrast, an application at 1-leaf stage rice reduced stand up to 68%. Application rate, timing, and formulation are important factors to consider if the use of pendimethalin in water-seeded rice is to be pursued.

Breeding Sunflower (Helianthus annuus) Assisted With Speed Breeding Drough Tolerance Tests

Sunflower production in the world is expending towards marginal areas, along with rapid changes in cultural practises like no-till planting and weed management. The frequency and severity of abiotic constraints also rise as a result of climate change. Helianthus annuus is well-known for its adaptability to a wide range of agronomic conditions, by its robust root system that is capable of absobing water from deeper soils. However, water stress lowers grain yields and fatty acid content with complex phenotypic, physiological and biochemical signs. In this study which was carried out to develop parental lines tolerant or high-tolerant to drought, physiological screenings were carried out on 8 sunflower genotypes. Genotypes were planted in pots in a greenhouse and grown at three different irrigation levels (I100, I66 and I33). The genotypes were watered together until they reached the 6-8 leaf stage. Then, each genotype was managed and irrigated solely. Number of days between sowing and floweing days, number of days between sowing and number of days between sowing and number of days to transfer the embryo to the nutrient medium, plant height, head diameter, number of seeds in the head was between 52-67 days; 65-80 days; 50-200 cm; 3.0-13.0 cm; 25-500 pieces, respectively. Plant weight, plant high, root length, number of leaf, nnmber of days from transplant to glasshouse, number of days from transplant to field was between 0.22-0.45 g; 2.09-4.62 cm; 1.70-5.27 cm; 3.60-5.87 pieces; 5 or 6 days; 10-12 days, respectively. In the experiments, it was found that two and a half generations could be achieved in one year. The genotypes K26-33 and K78-100 are located closest to the center as the most ideal genotypes in terms of the examined characteristics. In the MS environment, in terms of the characteristics examined, the genotypes K105-100, K78-100, K105-66, K26-100 and K1-100 were the preferred genotypes as they are located close to the center.

Evaluation of Sweet Pepper Genotypes for Yield and Quality in Open Field Using Plastic Mulch in Mid Hill Condition of Nepal

Sweet pepper is an emerging high value vegetable crop. There are few numbers of varieties recommended in Nepal despite of having immense commercial farming potentiality. An experiment was conducted during 2020 and 2021 at National Horticulture Research Centre, Khumaltar, in open field condition to identify high yielding capsicum genotype with longer postharvest shelf life. The field experiment was done by using the Randomized Complete Block Design (RCBD) with four replications for each treatment and the lab experiment for postharvest shelf life was studied in first year using Completely Randomized Block Design (CRD) with three replications for each treatment. The six elite capsicum genotypes under study were HRDCAP-001, HRDCAP-003, HRDCAP-004, HRDCAP-005, HRDCAP-006, and California Wonder (standard check variety). The research plot was mulched with 25-micron plastic and 4-6 leaf stage seedlings transplanted making holes in mulch at the spacing of 60 cm x 45 cm. Among the tested genotypes, HRDCAP001 and HRDCAP005 were found to be promising in terms of fruit length, fruit weight, yield per plant and yield per hectare followed by HRDCAP006 during a two-year experiment. The genotype HRDCAP001 was rich in vitamin C content with less spoilage loss while HRDCAP006 was observed most fresh followed by California Wonder and HRDCAP001 respectively. Overall, the genotype HRDCAP001 was found to be the superior among all the genotypes in terms of yield and quality parameters. However, a multi-location farmer’s field trial should be conducted for further verification and varietal development purpose.