Left Injury Research Articles

Effect of surrounding landscape on Popillia japonica abundance and their spatial pattern within Wisconsin vineyards.

Landscapes surrounding agroecosystems can provide resources that may benefit insect pests. This project examined the influence of the surrounding landscape on the abundance and spatial pattern of Popillia japonica (Coleoptera: Scarabaeidae) in vineyards. Twenty vineyards across Southern Wisconsin, spanning a gradient of 5-80% cropland in a 1.5km radius surrounding landscape, were sampled in 2017 and 2018 for P. japonica adults and leaf injury. The distribution of P. japonica and leaf injury was assessed by sampling along a transect at the edge, halfway from the edge to the center, and at the center of each vineyard. The proportion of cropland and pasture in the surrounding landscape along with abiotic factors of temperature, precipitation, longitude, and pesticide use (determined using Environmental Impact Quotient) were included in models to explain the variation of P. japonica abundance and leaf injury. No significant relationship was observed between proportion cropland in the surrounding landscape and P. japonica abundance or leaf injury. Combined effects of pasture, longitude, and temperature best explained variation in the abundance of P. japonica adults while longitude, temperature and EIQ best explained variability in leaf injury. Vineyards with more pastures in the surrounding landscape, located further east, and with higher temperatures, generally had more P. japonica adults and vineyards further east with higher temperature and lower EIQ pesticide use generally had higher levels of leaf injury. Additionally, variability in weekly temperature and precipitation influenced weekly abundance, with higher temperatures and less precipitation resulting in greater weekly abundance of P. japonica adults. Significantly more adult P. japonica and greater leaf injury were found at the edges than in the center of vineyards. Our results suggest beetles from the surrounding landscape likely contribute to populations of P. japonica adults found feeding on vines on vineyard edges, and P. japonica abundance and associated leaf injury are influenced by geographical location, local weather conditions, and pesticide use.

Toxicity of Bacillus thuringiensis Strains to Six Lepidopteran Pests of Brazilian Agricultural Landscape.

The first step for biological insecticide production is the evaluating of the pathogenicity and strains virulence of entomopathogens against the target pests. Bacillus thuringiensis (Bt) is widespread in nature, lethal pathogen of a range of orders and the most widely used entomopathogenic biological control agent. Therefore, our objective was to study the susceptibility of six important lepidopteran pests in Brazilian agricultural production systems, Anticarsia gemmatalis(Hübner),Chrysodeixis includens(Walker)Helicoverpa armigera(Hübner), Spodoptera cosmioides(Walker), S. eridania(Cramer), and S. frugiperda(Smith), to Bt strains. In vitro bioassays were conducted with neonate larvae exposed to two Bt strains, 1680A and 775E, in seven concentrations of spores and protein crystals. After 7days, the mortality was evaluated and indicated that lethal concentration (LC50) for 775E strain ranged from 7.72 × 104 to 2.45 × 106 spores mL-1 and for 1608A strain from 5.63 × 103 to 1.21 × 106 spores mL-1. The strain 1608A was more toxic for A. gemmatalis and H. armigera than 775E strain, and then was further evaluated in greenhouse bioassays with maize and soybean plants infested separately with target insects. The strain 1608A showed an efficient control for most insect species studied in the greenhouse bioassays, promoting considerable reduction in leaf injury and demonstrating a high potential in biological control of important lepidopteran species in crop production systems in Brazil.

Critical analysis of the potential of Psidium guajava cv Paluma (guava tree) for ozone biomonitoring under seasonal subtropical climate

• Psidium guajava is an ozone subtropical bioindicator. • Air temperature and relative humidity are important variables for ozone bioindication. • Multivariate analysis is a useful tool for biomonitoring in marked seasonality environments. Psidium guajava cv. Paluma (guava) has been emphasized as good indicator of phytotoxic tropospheric O 3 levels in studies conducted under both controlled and field conditions. However, its performance as bioindicator was never critically evaluated under subtropical climate featured by well-defined wet and dry seasons. The current field study provided new contributions on this aspect. Guava cv. Paluma plants were exposed to ozone in several locations of a metropolitan region in SE Brazil - which is featured by well-defined climate seasonality - to collect data to be used to describe seasonal and spatial variations in leaf injury index and in other leaf traits. Multilinear biomonitoring model was also adjusted for different O 3 pollution descriptors (daily O 3 concentration, AOT40, SUM00 and SUM60), meteorological conditions (air temperature and relative humidity, solar radiation, and vapor pressure deficit) and morphological leaf traits (visible leaf injury, leaf area, leaf dry mass, and leaf mass per leaf area). Visible leaf injuries tended to be higher in locations near the industrial pole. Autumn was the season when guava plants recorded the highest leaf injury caused by O 3 . Linear regression analysis did not indicate significant association between different O 3 descriptors and mean leaf injury; however, multilinear regression analysis has shown that other independent variables increased the bioindicator model’s explicability (R 2 = 0.67). Mean leaf injury observed for the 3rd, 4th and 5th oldest guava cv. Paluma leaves were predicted based on combined effects of air temperature and relative humidity, as well as on O 3 expressed as AOT40. The other leaf traits were excluded from the multilinear model. The adjusted model was validated as significant tool for future studies about air quality in subtropical regions with seasonal climate.

Respuesta de Commelina erecta L. a dos formulados de glifosato, y rol del almidón y de las ceras epicuticulares en la sensibilidad al glifosato

The aim of this study was to evaluate the effects of two formulations of glyphosate on adult plants and seedlings of Commelina erecta L., and to determine whether stem starch storage and epicuticular waxes of leaves are involved in plant sensitivity to this herbicide. The formulations used were isopropylamine salt (IPA) and diammonium salt (DA). All measured growth parameters and chlorophyll were negatively affected by both formulations. The IPA formulation showed a higher decrease in the branching rate and phyllochron, whereas the DA formulation showed a higher decrease in the elongation rate, chlorophyll content at 48 hours after application in adult plants, and the starch proportion in the stem basal section, and caused more leaf injuries. All plants of C. erecta presented starch storage in the both stem section. After glyphosate application, stem starch proportion of the basal section evolved differently in both growth stages, whereas stem starch proportion of the apical section showed an irregular variation. The amount of epicuticular waxes was higher in adult plants. These results show that both glyphosate formulations are ineffective for the management of C. erecta. The low sensitivity to glyphosate in C. erecta, especially in plants higher than five leaves, could be related to starch storage in stem and epicuticular waxes on leaves.

Precise maize detasseling base on oriented object detection for tassels

The maize detasseling process was gradually automated with the continuous promotion of the maize detasseling machine. Nevertheless, some problems are gradually becoming more prominent for it. Most maize detasseling machine has a simple maize tassels detection system. That is, the height of the crop was identified, and not the specific information on the maize tassels, leading to low detasseling precision and a high leaf injury rate during maize detasseling machine working. Aiming at these issues, this paper proposed a novel method for the maize tassel pose estimation based on computer vision and oriented object detection. Specifically, a two-step framework for maize tassel pose estimation is developed. Firstly, the maize plant is captured from above, then the maize tassels and the second leaf’s vein are posed in the horizontal plane, and their poses are matched to the oriented bounding box. Second, an oriented bounding box is generated according to the Oriented R-CNN model detection. Since maize tassels in the field differ in size and the morphological color of different growth stages, estimating the maize tassel pose accurately by the angle of the oriented bounding box alone is unfeasible. Therefore, these pixels of the oriented bounding box were put into the Look Twice module to extract the critical information about maize tassels, which can accurately determine the final pose of the maize tassels. Finally, evaluation metrics on the test set indicate the proposed method performed with correct maize tassels pose estimation rate of 88.56% and 29.57 Giga Floating-point Operations (GFLOPs), which indicated that the feasibility of maize tassel poses estimation using the proposed method. This study provides the possibility and foundation for precise maize detasseling in maize detasseling machines.

Selenium enhances chilling stress tolerance in coffee species by modulating nutrient, carbohydrates, and amino acids content.

The effects of selenium (Se) on plant metabolism have been reported in several studies triggering plant tolerance to abiotic stresses, yet, the effects of Se on coffee plants under chilling stress are unclear. This study aimed to evaluate the effects of foliar Se application on coffee seedlings submitted to chilling stress and subsequent plant recovery. Two Coffea species, Coffea arabica cv. Arara, and Coffea canephora clone 31, were submitted to foliar application of sodium selenate solution (0.4 mg plant–1) or a control foliar solution, then on day 2 plants were submitted to low temperature (10°C day/4°C night) for 2 days. After that, the temperature was restored to optimal (25°C day/20°C night) for 2 days. Leaf samples were collected three times (before, during, and after the chilling stress) to perform analyses. After the chilling stress, visual leaf injury was observed in both species; however, the damage was twofold higher in C. canephora. The lower effect of cold on C. arabica was correlated to the increase in ascorbate peroxidase and higher content of starch, sucrose, and total soluble sugars compared with C. canephora, as well as a reduction in reducing sugars and proline content during the stress and rewarming. Se increased the nitrogen and sulfur content before stress but reduced their content during low temperature. The reduced content of nitrogen and sulfur during stress indicates that they were remobilized to stem and roots. Se supply reduced the damage in C. canephora leaves by 24% compared with the control. However, there was no evidence of the Se effects on antioxidant enzymatic pathways or ROS activity during stress as previously reported in the literature. Se increased the content of catalase during the rewarming. Se foliar supply also increased starch, amino acids, and proline, which may have reduced symptom expression in C. canephora in response to low temperature. In conclusion, Se foliar application can be used as a strategy to improve coffee tolerance under low-temperature changing nutrient remobilization, carbohydrate metabolism, and catalase activity in response to rewarming stress, but C. arabica and C. canephora respond differently to chilling stress and Se supply.

Transgenic poplar trees overexpressing AtGolS2, a stress-responsive galactinol synthase gene derived from Arabidopsis thaliana, improved drought tolerance in a confined field.

Drought is an abiotic stress that limits plant growth and productivity, and the development of trees with improved drought tolerance is expected to expand potential plantation areas and to promote sustainable development. Previously we reported that transgenic poplars (Populus tremula × P. tremuloides, T89) harboring the stress-responsive galactinol synthase gene, AtGolS2, derived from Arabidopsis thaliana were developed and showed improved drought stress tolerance in laboratory conditions. Herein we report a field trial evaluation of the AtGolS2-transgenic poplars. The rainfall-restricted treatments on the poplars started in late May 2020, 18months after transplanting to the field, and were performed for 100days. During these treatments, the leaf injury levels were observed by measuring photosynthetic quantum yields twice a week. Observed leaf injury levels varied in response to soil moisture fluctuation and showed a large difference between transgenic and non-transgenic poplars during the last month. Comparison of the leaf injury levels against three stress classes clustered by the machine learning approach revealed that the transgenic poplars exhibited significant alleviation of leaf injuries in the most severe stress class. The transgenes and transcript levels were stable in the transgenic poplars cultivated in the field conditions. These results indicated that the overexpression of AtGolS2 significantly improved the drought stress tolerance of transgenic poplars not only in the laboratory but also in the field. In future studies, molecular breeding using AtGolS2 will be an effective method for developing practical drought-tolerant forest trees.

Efficacy of mineral oils against San Jose scale and European red mite on apple

Field efficacy of horticulture mineral oil Rilso 999 and MAK All Season at different concentrations were evaluated at two locations i.e., Lar (District Ganderbal) and Hajin (District Bandipora) of J&K during 2017 and 2018, all the treatments were significantly superior in terms of mortality of San Jose scale Quadraspidiotus perniciosus (Comstock) (SJS) and European red mite (ERM) Panonychus ulmi (Koch) as compared to untreated control. The cumulative mean mortality of SJS (58.08% and 62.20%) and ERM (58.69% and 53.65%) at recommended dose of 7.5 ml/ l of water both for standard check (MAK All Season) and Rilso999, respectively. Maximum (27.14 and 19.63 %) cumulative mortality of Amblyseius spp. and Coccinellids were recorded with Rilso999@ 10 ml/ l of water, respectively. No phytotoxicity symptoms viz., leaf injury, yellowing, wilting, necrosis, hyponasty and epinasty were observed with Rilso999 at 15 ml/ l of water. Maximum yield (246.16 kg/tree) was attained with MAK (standard check) @7.5 ml/ l of water.

Assessment of solomon 300 OD (Betacyfluthrin 90 + Imidacloprid 210 OD) as phtotoxixity and effects on natural enimies of sucking insect pests in kinnow plants

The trial for study was on orchard of Agricultural Research Station Srigangangar of kinnow 2 trees per treatment/ replication during 2016-2017. Eight treatments including control were evaluated and each treatment was replicated three times and using RBD to work bio-effeciacy of natural enemies of sucking insect pests of kinnow. Observations in each plot separately on natural enemies’ population were also recorded one days before of spray and 3, 7, 10 and 14 days after spray and evaluated from pooled data the natural enemies population has reduced some extend 3rd after spray and again increased also no ill effect of the natural enemies’ population. Out of these treatments two treatments one using 7 ml/ha and 14 ml/hawas taken as phyto-toxicity observation. No phyto toxicity symptoms was observed on number of leaves and infested leaves per twigs from 5 randomly selected twigs by viewing symptoms like leaf injury, yellowing, stunting, necrosis, epinasty and hyponasty in the leafs.

Effects of Shading Nets on Reactive Oxygen Species Accumulation, Photosynthetic Changes, and Associated Physiochemical Attributes in Promoting Cold-Induced Damage in Camellia sinensis (L.) Kuntze

Climate change and extreme weather affect tea growing. A competitive tea market needs quick, short-term solutions. This study evaluates the effects of various shade nets under mild and extreme cold stress on tea leaf physiology, photosynthetic alterations, antioxidant activities, and physiochemical characteristics. Tea plants were treated with SD0 (0% non-shading), SD1 (30% shading), SD2 (60% shading), and SD3 (75% shading). The 30%, 60%, and 75% shade nets shielded tea leaves from cold damage and reduced leaf injury during mild and extreme cold conditions compared with SD0% non-shading. Shading regulates photochemical capacity and efficiency and optimizes chlorophyll a and b, chlorophyll, and carotenoid contents. Moreover, carbon and nitrogen increased during mild cold and decreased in extreme cold conditions. Shading promoted antioxidant activity and physiochemical attributes. In fact, under 60% of shade, superoxide dismutase, peroxidase, catalase, and ω-3 alpha-linolenic acid were improved compared with SD0% non-shading during both mild and extreme cold conditions. From these findings, we hypothesized that the effect of different shades played an important role in the protection of tea leaves and alleviated the defense mechanism for “Zhong Cha 102” during exposure to a cold environment.

Urban afforestation: using phytotoxicity endpoints to compare air pollution tolerance of two native Brazilian plants Aroeira (Schinus terebinthifolius) and Cuvatã (Cupania vernalis).

Urban afforestation can mitigate the effects of air pollution, but the suitability of plant species for this purpose needs to be determined according to pollution intensity and climate change. The goal of this study was to evaluate the sensitivity of different phytotoxicity endpoints using two native Brazilian plant species as models, Aroeira (Schinus terebinthifolius) and Cuvatã (Cupania vernalis). The sensitivity parameters evaluated could help in selecting the most air-pollution-tolerant plant species for use in urban afforestation programs. The two plant species were exposed, in a greenhouse, to the combustion gases of a diesel engine for 120 days, with daily intermittent gas exposure. Every 30 days, leaf injury (chlorosis and necrosis), biomass, and physiological/biochemical parameters (proteins, chlorophyll, and peroxidase enzyme activity) were evaluated for both plant species. For the two selected species, the endpoints studied can be ranked according to their sensitivity (or inversely the tolerance) to diesel oil combustion gases in the following order: peroxidase > biomass ≈ chlorophyll > protein > leaf injury. The endpoint responses of higher plants can be used to assess the suitability of particular plant species for use in urban afforestation areas with relatively intense vehicle traffic.

Black Pecan Aphid (Hemiptera: Aphididae) Management on Pecan When Gibberellic Acid Is Applied Concurrently With Broad-Spectrum Insecticides.

Aphids (Hemiptera: Aphididae) are serious pests of pecan foliage (Carya illinoinensis [Wangenh.] K. Koch). The black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), feeds on pecan foliage and elicits leaf chlorosis that can cause defoliation. In contrast, the blackmargined aphid, Monellia caryella (Fitch) (Hemiptera: Aphididae), and yellow pecan aphid, Monelliopsis pecanis Bissell (Hemiptera: Aphididae), feed on pecan foliage but do not elicit chlorotic feeding injury. Application of gibberellic acid (GA3) to pecan foliage reduces chlorotic foliar injury and nymphal populations of the black pecan aphid. GA3 has potential to manage black pecan aphid later in the season when broad-spectrum insecticides are used to control direct pests of pecan nuts but also inadvertently induce aphid outbreaks. Here, broad-spectrum insecticides were used with GA3 or aphicides in orchard trials for 2 yr. Populations of aphids and natural enemies along with chlorotic feeding injury on foliage were assessed. When used concurrently with GA3 or aphicides, broad-spectrum insecticides did not flare black pecan aphid populations. However, combined populations blackmargined aphids and yellow pecan aphids were higher in treatments with GA3 than with an aphicide or in the control treatment during one of two years. Application of GA3 or the aphicide often led to significantly less chlorotic injury than observed in the control. Surprisingly, natural enemies were not significantly affected by broad-spectrum insecticides when applied concurrently with GA3. These results show that GA3 can be used as part of a late-season IPM strategy to protect foliage from localized chlorotic leaf injury elicited by the black pecan aphid.

Effects of soil fluoride pollution on wheat growth and biomass production, leaf injury index, powdery mildew infestation and trace metal uptake

Fluoride (F) is an emerging pollutant that originates from multiple sources and adversely affects plant growth and nutrient bioavailability in soil. This greenhouse study investigated the effects of soil F (0, 10, 20, 50, 100, 200 mg kg−1) on morpho-physiological growth characteristics of wheat, soil F contents, and bioavailability and uptake of F, phosphorus (P), sulphur (S), potassium (K), calcium (Ca), magnesium (Mg), aluminium (Al), iron (Fe), manganese (Mn), silicon (Si) and zinc (Zn) by wheat. Higher F significantly reduced plant height and number of leaves particularly at early growth stages and increased visible leaf injury index. Powdery mildew infestation coincided with leafy injury and was higher in elevated soil F treatments. Fluoride treatments (>50 mg kg−1) significantly increased water (H2O)- and calcium chloride (CaCl2)-extractable F contents in soil. Water-extractable soil F contents from soil in all concentration were higher than CaCl2-extractable F. This increased F bioavailability resulted in significantly higher F uptake and accumulation in live leaves, dead leaves and grains of wheat which followed order: live leaves > dead leaves > grains. Leaf injury index and number of dead leaves correlated significantly positively with soil H2O- and CaCl2-extractable F contents. Patterns of nutrient (P, K, S) and trace metals (Al, Ca, Mg, Fe, Mn, Si, Zn) varied significantly with F concentrations and between live and dead leaves, and grains except for Zn. Dead leaves generally had higher nutrients and trace metals than live leaves and grains. Fluoride contents in live leaves, dead leaves and grains showed positive correlations with nutrient elements but negative with trace metals. Number of dead leaves correlated negatively with Al, Ca, Fe, Mg, S and Si but positively with P and Zn contents in dead leaves whereas leaf injury index showed positive correlation with Fe, K, P, Si, Zn, S but negative with Al, Ca and Mg contents. These observations provided evidence of higher F uptake and associated impairment in nutrient and trace metal accumulation which caused leaf injury accompanied by powdery mildew infestation in wheat. However, further research in the region is required to confirm the relationship between F pollution, leaf injury and trace metal accumulation in crops under field conditions.

A 6-year field monitoring of fall armyworm, Spodoptera frugiperda, in transgenic Bt maize in Brazil

A 6-year field monitoring study was designed to compare the presence of fall armyworm Spodoptera frugiperda (J. E. Smith), leaf injury, its parasitoids, 100 seed weight, and seed yield of Bt maize hybrids approved for commercialization in the Brazilian market. Field trials were planted in two municipalities, divided into two periods, from 2011 to 2014 (period I), and due to the approval of different Bt hybrids, from 2015 to 2016 (period II). Treatments were Bt, non-Bt maize and all non-Bt maize sprayed with insecticide methomyl. Six Bt-maize hybrids were planted, expressing the following proteins: Cry1Ab, Cry1F, Cry1A.105 (Cry1Ab +Cry1Ac +Cry1F), Cry2Ab2a and Vip3. In 2015 and 2016 Bt Powercore was planted due to its commercial approval. The number of S. frugiperda larvae for most Bt hybrids was lower than on non-Bt hybrids, except for Fórmula TL and Herculex in period II, in both municipalities. In period I, Bt hybrids VT, VT 2 and Viptera showed almost no injury on their leaves, despite the high number of fall armyworm larvae found in plants. Different parasitoids emerged from larvae from Bt and non Bt hybrids: Archytas sp., Campoletis sp., Chelonus sp., Eiphosoma sp. and Ophion luteus. The average 100 seed weight was higher in municipality from Sete Lagoas for all Bt hybrids, non-Bt hybrids and non-Bt hybrids sprayed with methomyl, when compared to Nova Porteirinha during period I. Fórmula TL, non-Bt Fórmula TL sprayed with methomyl, and non-Bt Fórmula TL showed the lowest seed yield in both municipalities and periods.

Physiological and biochemical characteristics of two contrasting clones of Hevea brasiliensis under cold stress

Physiological and biochemical responses of two Hevea clones, differing in cold tolerance potential, namely, RRII 105 (susceptible) and SCATC 88/13 (tolerant) were assessed under low temperature exposure. They were accustomed under controlled conditions (30°C/22°C day/night) for one week before the actual low temperature treatment (15°C/7°C day/night) for two weeks and then allowed for a recovery period (30°C/22°C day/night) of three days. The objective of the experiment was to evaluate the changes in physiological and biochemical characteristics and to determine the ability of the genotypes to recover from cold injury upon exposure to subsequent normal temperature. Photosynthetic pigment contents were more sensitive to cold stress induced photo-oxidation; however, the clone SCATC 88/13 could maintain better level of pigments and remained green with less level of leaf yellowing even after two weeks of stress imposition. A fast recovery of growth on re-warming was noticed in this clone than RRII 105. Cold stress induced leaf injury resulted in significant inhibition of photochemical efficiency (Fv/Fm) and effective quantum yield (O PS II) of PS II in both the clones but the decline was comparatively lesser in SCATC 88/13. During stress recovery periods the rate of PS II repairing was better in SCATC 88/13 than susceptible clone. Comparatively the level of antioxidant, glutathione and rate of antioxidant enzymes activities such as total peroxidase and SOD were high during stress and recovery periods in SCATC 88/13 than RRII 105. The clone SCATC 88/13 maintained a low level of lipid peroxidation during all the phases. Low temperature stress could impair different physiological activities such as antioxidant defense systems and photochemical reactions of photosynthesis and enhance the rate of lipid peroxidation, pigments degradation and photo-inhibition. The results obtained indicate lesser cold injury and faster stress recovery on re-warming in clone SCATC 88/13.

A New Scoring Technique for Assessing the Infestation of Maize Fall Armyworm, Spodoptera frugiperda (J.E. Smith)

Maize fall armyworm, Spodoptera frugiperda (J.E. Martin (Noctuidae: Lepidoptera), first recorded in the Americas spread to Africa during 2016 and later spread to more than 40 countries including India during July, 2018. Infestation by maize fall armyworm results in extensive defoliation besides damage to tassels and cobs at later stages of the crop. The infestation levels are measured through various injury rating scales of which the 1-9 whorl leaf injury rating scale (Davis et al., 1992; Ni et al., 2011) is the mostly used one. It was felt that, the Davis 1-9 scale proposed by Davis et al. (1992) was prone to observer bias in field experiments conducted at Tamil Nadu Agricultural University by a team of researchers and students. Thus, a new TNAU 1-5 scale was evaluated which was more feasible, precise, easy and less time consuming compared to modified Davis et al., (1992) 1-9 scale proposed by Ni et al.

Colonization of Piriformospora indica enhances insect herbivore resistance of rice plants through jasmonic acid- and antioxidant-mediated defense mechanisms

ABSTRACT Piriformospora indica (P. indica) is a mutualistic endophyte that colonizes plant roots. In this study, effects of P. indica on rice resistance against rice leaffolder (Cnaphalocrocis medinalis Guenée) were investigated. Growth inhibition and leaf injury caused by leaffolder larvae infestation in P. indica-colonized rice was significantly alleviated. Moreover, growth retardation was observed in larvae which fed on P. indica-colonized plants. JA-Ile levels and trypsin inhibitor activities in leaf tissues of P. indica-colonized plants were higher than those in noncolonized plants under leaffolder-infested conditions. P. indica effects on increasing trypsin inhibitor expression and reducing larval growth were repressed by aspirin. JA signaling drives P. indica-enhanced insect resistance in rice, and trypsin inhibitors might be candidates involved in this mechanism. Changes in antioxidant enzyme activities and malondialdehyde levels in P. indica-inoculated plants were observed, and it was demonstrated that oxidative stress induced by insect infestation could be reduced in P. indica-colonized plants.

Effect of Elevated Tropospheric Ozone on Vigna Mungo L. Varieties

ABSTRACT Tropospheric ozone (O3) is widely recognized as the most critical, regional atmospheric pollutant causing significant losses to agricultural productivity due to its phytotoxicity over agricultural areas and is expected to increase in future. In view of rising tropospheric ozone concentration over Indian regions, the present study aimed to evaluate the effect of elevated ozone stress on pulse crop blackgram (Vigna mungo L.), which contributes the major share of protein. The blackgram varieties namely CO 6, VBN 1, VBN 2, VBN 3, VBN 5, VBN 6, VBN 7, and VBN 8 were grown in open top chambers and factorial completely randomized block design was followed. The plants were exposed to elevated ozone concentration (50 and 100 ppb) from 10.00 h to 17.00 h over 10 days at flowering stage, with a weighted average ozone concentration of 50.1 and 101.2 ppb. Both the elevated ozone treatments significantly affected the plant physiological, biochemical, growth, and yield traits of all test varieties. On an average across eight blackgram varieties, decrease in chlorophyll content by 33.83 and 42.41%, stomatal conductance by 28.25 and 40.51% and photosynthetic rate by 29.43 and 42.30% exposed to 50 and 100 ppb ozone were observed, respectively. Correspondingly, the number of pods per plant decreased by 30.82 and 32.65%, 100 grain weight by 7.75 and 21.23% and plant weight by 16.03 and 21.23%, respectively, which were significant at 5% level. Furthermore in the observed traits, significantly higher reduction was observed in VBN3, while the least reduction was observed in VBN8. The path analysis displayed that all the observed physiological, biochemical, growth, and yield traits positively regulated the yield except leaf injury percentage, malondialdehyde, and proline content. The principal component analysis of two elevated ozone treatments confirmed VBN8 as ozone tolerant and VBN3 as ozone sensitive variety. Hence, cultivation of VBN8 variety at ozone hotspot regions would be the best option to overcome ozone induced yield loss.

The soybean Phytoglobin1 (GmPgb1) is involved in water deficit responses through changes in ABA metabolism

Soybean (Glycine max), a major grain crop worldwide, is susceptible to severe yield loss due to drought. Soybean plants over-expressing and downregulating the soybean Phytoblobin1 (GmPgb1) were evaluated for their ability to cope with polyethylene glycol (PEG)-induced water deficit. Sense transformation of GmPgb1, which was more expressed in shoot tissue relative to roots, increased overall plant performance and tolerance to water stress by attenuating the PEG depression of photosynthetic gas exchange parameters and chlorophyll content, as well as reducing leaf injury and promoting root growth. The higher plant relative water content, as a result of GmPgb1 over-expression, was associated with higher transcript levels of three aquaporins: GmTIP1;5 and GmTIP2;5 GmPIP2;9, known to confer water stress tolerance. Opposite results were observed in plants suppressing GmPgb1, which were highly susceptible to PEG-induced stress. Transcriptional and metabolic analyses revealed higher ABA synthesis in dehydrating leaves of plants over-expressing GmPgb1 relative to those suppressing the same gene. The latter plants exhibited a transcriptional induction of ABA catabolic enzymes and higher accumulation of the ABA catabolite dehydrophaseic acid (DPA). Administration of 8′-acetylene ABA, an ABA agonist resistant to the ABA catabolic activity, was sufficient to restore tolerance in the GmPgb1 down-regulating plants suggesting that regulation of ABA catabolism is as important as ABA synthesis in conferring PEG-induced water stress tolerance. Screening of natural soybean germplasm also revealed a rapid and transient increase in foliar GmPgb1 in tolerant plants relative to their susceptible counterparts, thus confirming the key role exercised by this gene during water stress.

Response of morphological and biochemical traits of maize genotypes under waterlogging stress

Maize (Zea mays L.) is one of the most important cereal crops cultivated around the world. Waterlogging stress is a major production constraint of maize production in rain-fed agricultural systems. The main objective of this experiment was to investigate the effect of continuous waterlogging on morphological and biochemical traits of maize genotypes at the vegetative stage. Ten maize genotypes were treated under no waterlogging (control) and continuous waterlogging of five centimeters depth for 10 days. The treatments were applied to the plants at their 45 days of age. Visual leaf injury scores from Leaf 4 (youngest leaf is the reference point) to Leaf 7 separated tolerant and susceptible genotypes. Waterlogging stress significantly reduced the total number of live leaves and chlorophyll content in leaf tissues in susceptible genotypes. The anatomical study revealed that tolerant maize genotypes produce a large number of aerenchyma cells under waterlogging stress compared to susceptible genotypes. The enzymatic activities of ascorbate peroxidase (APX) and peroxidase (POD) exhibited a greater increase in tolerant genotypes than susceptible genotypes whereas the contents of reactive oxygen species (H2O2) greatly increased in susceptible genotypes than tolerant genotypes under waterlogging stress compared to control. Principal component 2 (PC2) indicated that increasing plant height in the genotypes BHM-14, BHM-13 and BHM-9 was associated with waterlogging tolerance. The findings of this experiment will add value to maize breeding to screen out maize genotypes for waterlogging stress tolerance.