Reduced Shoot Weight Research Articles

Screening of Crossandra (Crossandra infundibuliformis (L.) (Nees.) Genotypes for Root Lesion Nematode

An experiment was conducted with ten crossandra genotypes collected from various institutions and local sources at Department of Floriculture and Landscape Architecture, Horticultural College and Research Institute, Coimbatore. The experiment was laid out using FCRD design with three replications with genotypes uninoculated and inoculated with nematodes. Observations were taken after 60 days of inoculation. The results revealed that Nilakottai local and Arka Shravya recorded the least percentage of reduction of shoot weight (13.73 & 14.55%) and root weight (18.83 & 16.93%) under inoculated condition. The increased percentage of phenol, polyphenol oxidase, peroxidase activity and phenylalanine ammonia lyase was higher in Nilakottai local and Arka Shravya and the least was noticed in Dharmapuri local under inoculated conditions. The root necrosis percentage ranged from 7.05 to 21.17. The lowest root lesion percentage was recorded in genotype Nilakottai local (7.05) followed by Arka Shravya (8.67) and the highest necrosis percentage was observed in genotype Dharmapuri local (21.17). Resistant reaction was noticed in genotype Nilakottai local and Arka Shravya. Tolerant reaction was observed in genotype Delhi crossandra, Arka Ambara, Arka Chenna, Arka Shreeya and Arka Kanaka. The susceptible reaction was found in genotype Villupuram local, Neyveli local and Dharmapuri local.

Biosurfactant-Assisted Phytoremediation of Diesel-Contaminated Soil by Three Different Legume Species

This study aims to assess the impact of HydroBreak PLUS biosurfactant on the phytoremediation of diesel-contaminated soil by three legume plant species: Medicago sativa, Lotus corniculatus, and Melilotus albus. Legumes were grown in soil contaminated with diesel (4.0 g kg−1, 6.0 g kg−1) for 90 days, and the changes in soil diesel and nutrient concentrations, plant growth, and physiological parameters were measured. Diesel negatively affected the biomass production of all legumes, though the reduction in growth rate was observed only in L. corniculatus and M. albus. L. corniculatus had the highest diesel removal rate of 93%, M. albus had the lowest of 87.9%, and unplanted treatments had significantly lower diesel removal rates (up to 66.5%). The biosurfactant mitigated diesel-induced reduction in plant shoot and root weight and an increase in L. corniculatus root biomass (24.2%) were observed at 4.0 g kg−1 diesel treatment. The use of biosurfactant accelerated diesel removal from the soil, though the effect was diesel soil concentration and plant species-dependent. In unplanted treatments, the diesel removal rates increased by 16.4% and 6.9% in the treatments with 4 and 6 mg kg−1, respectively. The effect of biosurfactants on diesel removal by plants was less pronounced and reached 4.6% and 3.2% in the treatments with 4 and 6 mg kg−1, respectively. The study revealed that the phytoremediation efficiency could not be directly linked to plant physiological parameters as only M. sativa changes in plant growth corresponded well with photosystem II performance. Implementation of legumes and biosurfactants has a positive effect on soil quality by its enrichment with inorganic P and soluble phenols, while no enrichment in NO3− and NH4+ was observed.

Effects of drought on enzyme activities and hotspot distribution along plant roots

The frequency and severity of drought are projected to increase due to climate change, and Southeast Asia is no exception. Water scarcity hampers all biochemical processes in soil and induces stunted plant growth. While the rhizosphere harbors the most dynamic biochemical processes in the biosphere, the interaction mechanisms between residing microbes and plant roots under drought are poorly understood. In this research, soybean was planted in soil collected from the Red River Delta of Vietnam to test two hypotheses: (i) drought reduces rhizosphere enzyme activities and hampers the extent of the high enzyme activity along single root (from the root tips), and (ii) the turnover time of substrate by enzymes increases with decreasing soil moisture. The research aimed to characterize distributions of β-glucosidase and acid phosphatase enzymes in a distance from root tips. In addition, enzyme activities and plant root and shoot characteristics (length and weight) were investigated. The results demonstrated that shoot length was more impacted by drought than root length with the reduction of 25% for the former and 5% for the later. Meanwhile, the reduction in shoot weight was 61%, and root weight was 90% as the plant experienced drought conditions. The extent of a hotspot for enzymes along a single plant root, measured from the root tips, also decreased in response to drought. Furthermore, drought reduced both rhizosphere enzyme activities, resulting in a slower turnover time of β-D-glucopyranoside (MUF-G) and 4-methylumbelliferyl-phosphate(MUF-P) substrates. The research has shed light on the adverse impacts of drought on root-microbe interactions, which ultimately lead to poor crop growth.

Impact of rice straw biochar in association with inorganic fertilizers and Trichoderma harzianum on charcoal rot (Macrophomina phaseolina) of maize

Phytosanitary regulations concerning pesticide residues are among the most important problems faced by today's agricultural environment. Therefore, the purpose of this study was to produce and characterize indigenously produced biochar from raw material based on rice straw. The biochar synthesized at 480°C, was used as amendment at different volumetric concentrations (3 and 6%), along with in-organic fertilizers for restricting the development of charcoal rot (Macrophomina phaseolina), in maize (Zea mays L.) The scanning electron microscopy (SEM) analysis of rice straw biochar showed micro-cracks, rough texture, and intricately formed pores, thus showcasing the complex and porous nature of the rice straw biochar resulting from the pyrolysis process. The energy dispersive X-ray spectroscopy (EDX) analysis confirmed its carbonaceous composition (approximately 54%), with the presence of functional groups like hydroxyl and carboxyl, as well as trace amounts of potassium, calcium, and silicon. Maize grown in soil amended with 6% biochar showed significant reduction in shoot and root weights (51.72 and 74.11%, respectively) when compared to 3% biochar amended soil in the presence of M. phaseolina. Our results revealed that 3% rice straw biochar and Trichoderma harzianum proved most effective for the management of charcoal rot as indicated by lowest disease incidence and disease severity (40%, each). Maize showed variable degrees of defense mechanisms activation in response to soil biochar amendments. Biochar application rate of 6% did generally not improve the maize dry biomass production and tolerance to charcoal rot. These findings will surely help us understand biochar-induced changes in physiology of maize and possible activation of defense response against M. phaseolina

Tall Fescue Seedling Growth as Affected by Postemergence Herbicides

The objective of this greenhouse study was to evaluate tall fescue (Festuca arundinacea) seedling growth when seeded after herbicide application. Herbicide treatments included a nontreated control; 1.19 lb/acre 2,4-dichlorophenoxyacetic acid (2,4-D) + 0.32 lb/acre methylchlorophenoxypropionic acid (MCPP) + 0.32 lb/acre dicamba; 0.75 lb/acre quinclorac; and 0.06 lb/acre halosulfuron-methyl. Seeding was done at 0, 3, 7, or 14 days after herbicide application to soil media. Two identical experiments were conducted in the greenhouse: Expt. 1 seedling growth from January to March and Expt. 2 from May to July (temperatures higher). Seeding dates after herbicide application did not influence growth. Average dry shoot weight reductions and dry root weight reductions caused by postemergence herbicides were 2,4-D + MCPP + dicamba (33% shoot and 27% root in Expt. 2), quinclorac (30% shoot and 37% root in Expt. 2), and halosulfuron-methyl (51% shoot in Expt. 2; 81% root in Expts. 1 and 2). Although application of these herbicides before seeding in the field may result in no visual impact, they can impact seedling shoot and root growth, particularly under higher growth temperatures.

Effect of organic photovoltaic and red-foil transmittance on yield, growth and photosynthesis of two spinach genotypes under field and greenhouse conditions

The galloping rise in global population in recent years and the accompanying increase in food and energy demands has created land use crisis between food and energy production, and eventual loss of agricultural lands to the more lucrative photovoltaics (PV) energy production. This experiment was carried out to investigate the effect of organic photovoltaics (OPV) and red-foil (RF) transmittance on growth, yield, photosynthesis and SPAD value of spinach under greenhouse and field conditions. Three OPV levels (P0: control; P1: transmittance peak of 0.11 in blue light (BL) and 0.64 in red light (RL); P2: transmittance peak of 0.09 in BL and 0.11 in RL) and two spinach genotypes (bufflehead, eland) were combined in a 3 × 2 factorial arrangement in a completely randomized design with 4 replications in the greenhouse, while two RF levels (RF0: control; RF1: transmittance peak of 0.01 in BL and 0.89 in RL) and two spinach genotypes were combined in a 2 × 2 factorial in randomized complete block design with four replications in the field. Data were collected on growth, yield, photosynthesis and chlorophyll content. Analysis of variance (ANOVA) showed significant reduction in shoot weight and total biomass of spinach grown under very low light intensities as a function of the transmittance properties of the OPV cell used (P2). P1 competed comparably (p > 0.05) with control in most growth and yield traits measured. In addition, shoot to root distribution was higher in P1 than control. RF reduced shoot and total biomass production of spinach in the field due to its inability to transmit other spectra of light. OPV-RF transmittance did not affect plant height (PH), leaf number (LN), and SPAD value but leaf area (LA) was highest in P2. Photochemical energy conversion was higher in P1, P2 and RF1 in contrast to control due to lower levels of non-photochemical energy losses through the Y(NO) and Y(NPQ) pathways. Photo-irradiance curves showed that plants grown under reduced light (P2) did not efficiently manage excess light when exposed to high light intensities. Bufflehead genotype showed superior growth and yield traits than eland across OPV and RF levels. It is therefore recommended that OPV cells with transmittance properties greater than or equal to 11% in BL and 64% in RL be used in APV systems for improved photochemical and land use efficiency.

Identifying Lettuce Accessions for Efficient Use of Phosphorus in Hydroponics

Lettuce (Lactuca sativa L.) is the most common leafy vegetable produced hydroponically in the United States. Although hydroponic systems are advantageous due to lower pest and disease pressure, and reduced water and nutrient requirements, the increasing prices of fertilizers, including phosphorus (P), still influences the profitability of hydroponic production of lettuce. Characterizing lettuce germplasm capable of producing high yield using less P inputs may help reduce fertilizer use, production costs, and P loads in wastewater. In this study, 12 lettuce accessions were grown in four experiments in a nutrient film technique system. In the first two experiments, the treatments consisted of two P concentrations (3.1 and 31 mg·L−1). Lettuce cultivated with 3.1 mg·L−1 of P had variable shoot and root biomass, root–shoot ratio, P uptake efficiency, and P utilization efficiency, indicating the existence of genetic variation. Five accessions (‘Little Gem’, 60183, ‘Valmaine’, BG19-0539, and ‘Green Lightning’) were considered efficient to P because produced similar shoot biomass with the low and high P treatments. In the third and fourth experiments, the treatments consisted of two P sources (monosodium phosphate (NaH2PO4) and tricalcium phosphate [TCP; Ca3(PO4)2]. Initially, extra 5 mM of calcium (Ca) was added to the TCP solution to reduce the TCP solubility and, hence, P bioavailability to plants. All accessions produced similar shoot and root weight with both treatments, indicating that the TCP treatment did not cause low-P stress to the plants. After, the extra Ca concentration added to TCP was increased to 10 mM, resulting in low-P stress and a significant reduction in shoot weight of all accessions. Despite the severe P stress, ‘Little Gem’ and 60183 were among the accessions with the least shoot weight reduction in the TCP treatment. Variability was observed in root biomass root–shoot ratio among accessions under the TCP treatment, suggesting that lettuce accessions responded differently to P stress conditions. The genetic variation for P use efficiency (PUE) and PUE-related traits in lettuce grown hydroponically suggests the feasibility of breeding new lettuce cultivars from elite lettuce germplasm adapted to low P availability in hydroponics.

Synthesis of phytostabilized zinc oxide nanoparticles and their effects on physiological and anti-oxidative responses of Zea mays (L.) under chromium stress

Chromium (Cr) is a hazardous metal that has a significant risk of transfer from soil to edible parts of food crops, including shoot tissues. Reduction of Cr accumulation is required to lower the risk of Cr-exposed in humans and animals feeding on metal-contaminated parts of such plant. Zea mays is a global staple crop irrigated intensively with Cr-contaminated water. Consequently, the objective of this study was to investigate that FI-stabilized ZnO NPs could be used as an eco-friendly and efficient amendment to reduced Cr uptake and toxicity in Zea mays. To investigate the growth parameters, physiological, oxidative stress and biochemical parameters under different Cr-VI concentrations (10.0, 15.0, and 20.0ppm). Cr exposed Z. mays plants exhibited substantially reduced plant biomass, chlorophyll contents, and altered antioxidant enzyme activity compared to untreated control. The results revealed that foliar application of Fagonia-ZnO-NPs helps eliminate the harmful effects of Cr (VI), which can enter plants through soil pollution. Increased levels of proline, soluble sugars and various antioxidant enzymes reflected this. Mean comparisons showed that Cr stress led to a 33-50% reduction in fresh shoot weight, 73-170% in fresh root weight, 16-34% shoot length, 9.5-129% root length, Chlorophyll contents 20-33% (Chl a), 18-27% (Chl b) and 17-27% (car), 14-33% total soluble sugars, 54-170% proline content, 7-7.5% POD, 0.66-75% CAT and 32-77% APX enzyme activities compared to untreated plants. Application of FI-stabilized ZnO NPs led to an increase 21-77% in fresh shoot weight, 22-45%, fresh root weight, 3-35% shoot length, 24-154% root length, Chlorophyll contents 39-60% (Chl a), 15-79% (Chl b) and 28-82% (car), 19-52% total soluble sugars, 21-55% proline content, 14-43% POD, 34-95% CAT and 130-186% APX enzyme activities under 10, 15 and 20ppm Cr stress respectively, compared to Cr-treated plants. However, the principal component analysis revealed that chlorophyll contents, carotenoid, CAT, APX and length were in the same group and showed a positive correlation. These data collectively suggest that phytostabilized zinc oxide NPs may be an eco-friendly solution to mitigate Cr toxicity in agricultural soils and crop plants.

Impact of Salt stress on Morphology and Physiology of Maize Plants

Soil salinization negatively influences crop plants worldwide. Stress conditions can defer plant development and improvement, lessen productivity, and in outrageous cases cause plant death. The biomass, morphology, homeostasis, and functioning of the plant are reduced under the influence of salt stress. High rates of the salts inside the plant tissues are toxic metabolically and can lead to a reduction in root and shoot weight, oxidative stress, production of ROS, and inhibition of photosynthesis. Maize is an important fodder crop grown worldwide. Nutritional imbalance, reduced seed germination, vegetative growth, and uptake of the nutrients have been noticed in maize crops as a result of salt accumulation. Seedling vigor, development, and stress resistance ability of the maize crop have been improved by nutritional management and an effective, simple, and receptive way known as seed priming. Soaking of seeds in water before sowing, i.e. hydropriming and use of different chemicals, i.e. osmopriming is being practiced in this regard. These seed priming methods facilitate the treated plants with resistance against salinity, early growth, vigorous plant stand, and uniform germination. So, this review paper investigates the effect of salinity on maize crops and the efficacy of osmo and hydro priming methods against abiotic stresses, especially soil salinization.

Efficacy of Postemergence Herbicides for Control of Small-Leaf Spiderwort (Tradescantia fluminensis) in Florida

Tradescantia fluminensis (small-leaf spiderwort; SLSW) is a fast-growing herbaceous groundcover and one of the most problematic invasive plants in Florida. The objective of this research was to determine the efficacy of selected postemergence herbicides for SLSW control in greenhouse and field experiments in Florida. An additional objective was to determine if pre-cutting plants would increase herbicidal efficacy. In greenhouse experiments, cutting mature SLSW plants increased the control of most herbicides evaluated. Overall, triclopyr ester provided the highest level of control along with triclopyr amine, triclopyr choline, and glufosinate, all of which were similar. Few differences were observed between 2,4-D, aminopyralid, metsulfuron-methyl, sulfentrazone, and glyphosate and all provided ≤66% control as evidenced by shoot weight reduction. In field experiments, pre-cutting SLSW had no effect on herbicide efficacy. Triclopyr was again generally the most efficacious treatment, outperforming glyphosate, aminopyralid, glufosinate, and fluroxypyr on most evaluation dates, especially as trials progressed past 5 mo. Overall, data suggest that triclopyr would be the most effective option for SLSW management. However, as efficacy was noted with fluroxypyr, glyphosate, and glufosinate depending upon location, other options exist. Further research is needed to determine reapplication intervals and effects on nontarget native plants in order to develop comprehensive management plans.

Genetic Diversity and Pathogenicity of Verticillium dahliae Isolates and Their Co-occurrence with Fusarium oxysporum f. sp. vasinfectum Causing Cotton Wilt in Xinjiang, China.

Cotton production in Xinjiang, the largest cotton-producing area in China, has an increasingly serious disease threat from Verticillium dahliae. Eighty-five V. dahliae isolates were obtained from wilted cotton plants collected from eight counties in Xinjiang. The isolates were assessed for genotypic diversity by DNA sequence analysis and PCR molecular genotyping with specific markers for race 1, race 2, defoliating (D) pathotype, nondefoliating (ND) pathotype, and mating type idiomorph Mat1-2. Isolates belonged to lineages 1A or 2B, with three subgenotypes found in each lineage. All isolates tested positive for race 2 and Mat1-2 markers. All isolates in lineage 2B tested positive for the ND pathotype marker but only isolates in the major subgenotype in lineage 1A tested positive for the D pathotype marker. Pathogenicity assays on Gossypium hirsutum 'Acala 44' demonstrated no significant difference among subgenotypes within each lineage. Isolates in lineage 1A caused greater shoot weight reductions, percent leaf drop, and percent diseased leaves than isolates in lineage 2B. One isolate in each lineage for 1A and 2B was avirulent. Isolates in lineage 1A caused greater than 50% leaf drop and a 17-g shoot weight reduction compared with a 9% leaf drop and a 6-g shoot weight reduction by isolates in lineage 2B. Overall, 42% of the V. dahliae isolates from Xinjiang were D pathotype but the percentage varied widely among locations. Two plants had both pathotypes. Nineteen isolates of Fusarium oxysporum f. sp. vasinfectum VCG0114 (race 4) also were recovered from wilted plants in Xinjiang. Two plants had both Verticillium wilt and Fusarium wilt pathogens. Both pathogens should be considered when using or developing wilt resistant or tolerant materials for Xinjiang.

PRE and POST control of Praxelis clematidea, an emerging weed in Florida nursery production

AbstractPraxelis is an annual to short-lived perennial herb in the Asteraceae family and an emerging problematic weed species in Florida nurseries. The objective of these experiments was to determine efficacy of selected PRE and POST herbicides for control of praxelis. An additional experiment was conducted to determine efficacy of the same PRE herbicides for control of bluemink, a weed similar in appearance to praxelis that is also common in Florida. The granular herbicides dimethenamid + pendimethalin, flumioxazin, oxyfluorfen + pendimethalin, oxyfluorfen + prodiamine, and trifluralin + isoxaben were evaluated, along with spray-applied formulations of dimethenamid, indaziflam, and prodiamine + isoxaben. Flumioxazin consistently provided over 90% control of praxelis at both sites. Indaziflam control was inconsistent between the two sites, providing 100% control in Apopka but only a 22% reduction in weed counts in Balm. Oxyfluorfen + pendimethalin, oxyfluorfen + prodiamine, and prodiamine + isoxaben also provided control (57% to 97% reduction in shoot weight), albeit generally to a lesser degree than was observed with flumioxazin. All PRE herbicides provided similar control of both praxelis and bluemink, with the exception of dimethenamid and dimethenamid + pendimethalin, which reduced bluemink shoot weight more than praxelis. Clopyralid, glyphosate, and triclopyr all provided effective POST control of mature and flowering praxelis through 12 wk after treatment (WAT) and resulted in greater praxelis control than glufosinate. Results suggest that many commonly used PRE and POST herbicides would provide control of praxelis, but use of PRE and POST herbicides as well as sequential applications may be needed for long-term management.

Evaluation of safflower (Carthamus tinctorius L) genotypes against salinity stress

Safflower genotypes were evaluated for salinity stress using irrigation water with 5 EC levels through paper towel method. Among the 24 genotypes tried, performance of 5 genotypes was prominent in terms of shoot length and weight at 15 days growth. The genotype IC-406052 showed 23% reduction and genotype SSF-733 showed 65% reduction with EC of 10 dS/m against zero salinity. Highest reduction of shoot weight was noticed in SSF-733(54%) and minimum was recorded in IC-406052 (26%) with EC of 10 dS/m compared to zero salinity.

Susceptibility of some Plant Cultivars Cucumber and Watermelon to Root- Kont Nematode, Meloidogyne javanica under Greenhouse Conditions

Thirteen cultivars of cucumber Cucumis sativus and eight cultivars of watermelon Citrullis vulgaris were evaluated for their host response to Meloidogyne javanica. The nematode succeeded in developing and multiplying on all most tested cultivars from Cucurbitaceae plants. Cucumber cultivars Hisham, Waffir and Beitalpha the highest rate of nematode reproduction more than the rest of cultivars Emparator, Hayel and Sinai1 were classified as slightly resistant (SR ). While cultivars cucumber Bahy, BashaF1,Beitalpha, Ellama, Eshrak1, Fahd, HadyF1, Hisham,Paracoda, Waffir were classified as susceptible (S) hosts to M.javanica. Also, results showed that some of tested watermelon cvs Aswan F1, Giza 1, Giza 21 and Sugar Baby were classified as slightly resistant (SR) , and four cvs Al-Fahd, Al-Gawhra ,Charleston Gray123 and Crimson Sweet were classified as susceptible(S) hosts. Moreover, there were significant reduction in both shoot and root fresh weights of the tested all cultivars infected.

Susceptibility of Eucalyptus grandis and Acacia mearnsii seedlings to five Phytophthora species common in South African plantations

AbstractEucalyptus grandis and its hybrids, as well as Acacia mearnsii, are important non‐native trees commonly propagated for forestry purposes in South Africa. In this study, we conducted pathogenicity trials to assess the relative importance of five commonly isolated Phytophthora spp. (Phytophthora alticola, P. cinnamomi, P. frigida, P. multivora and P. nicotianae) from the plantation environment on E. grandis and A. mearnsii seedlings. Overall E. grandis was more susceptible to the tested Phytophthora spp. than A. mearnsii. Phytophthora cinnamomi was the only pathogen that had a significant negative effect on both the host tree species, leading to a reduction in root and shoot weight as well as to death in the case of E. grandis. Phytophthora alticola and P. nicotianae exclusively affected E. grandis and A. mearnsii, respectively. This study updated the current knowledge on the pathogenicity of Phytophthora spp. on two important non‐native commercially propagated tree species from South Africa.

Reproduction Ability and Growth Effect of Pin Nematode, Paratylenchus nanus, With Selected Field Pea Cultivars.

Greenhouse experiments were conducted to determine the reproductive ability and effect of the pin nematode Paratylenchus nanus from North Dakota on field pea cultivars. Reproduction of P. nanus was determined on seven field pea cultivars using naturally infested field soils at low (1,500/kg of soil) and high (4,500/kg soil) initial pin nematode densities. Nematode effect on plant growth and seed yield was evaluated at 4,500 P. nanus per 1 kg of soil by artificially inoculating P. nanus on six field pea cultivars. Reproductive factor (RF) of P. nanus was observed to be greater at the low density than the high density of the nematode. At the low population density, RF values ranged from 1.10 to 11.20, whereas at the high density, RF ranged from 1.20 to 2.50. In experiments evaluating P. nanus effects on cultivar growth, the nematode (4,500 P. nanus per 1 kg soil) caused reduction (P < 0.05) of plant height in most cultivars tested, and it also significantly impacted dry shoot weight and dry seed weight in some experiments. Plant height and shoot weight reductions were the highest in the cultivar Arcadia (up to 37 and 53%, respectively), with a dry seed weight reduction up to 32%. This research demonstrated for the first time the negative impact of P. nanus on field peas in controlled greenhouse conditions, which is an important step toward developing effective management strategies to improve the productivity of this leguminous crop.

Uncovering the Host Range for Maize Pathogen Magnaporthiopsis maydis.

The fungus Magnaporthiopsis maydis is a soil-borne, seed-borne vascular wilt pathogen that causes severe damage to sensitive Zea mays L. (maize) hybrids throughout Egypt, Israel, India, Spain, and other countries. It can undergo virulence variations and survive as spores, sclerotia, or mycelia on plant residues. Maize, Lupinus termis L. (lupine) and Gossypium hirsutum L. (cotton) are the only known hosts of M. maydis. Identification of new plant hosts that can assist in the survival of the pathogen is an essential step in restricting disease outbreak and spread. Here, by field survey and growth chamber pathogenicity test, accompanied by real-time PCR analysis, the presence of the fungal DNA inside the roots of cotton (Pima cv.) plants was confirmed in infested soil. Moreover, we identified M. maydis in Setaria viridis (green foxtail) and Citrullus lanatus (watermelon, Malali cv.). Infected watermelon sprouts had delayed emergence and development, were shorter, and had reduced root and shoot biomass. M. maydis infection also affected root biomass and phenological development of cotton plants but caused only mild symptoms in green foxtail. No M. maydis DNA was detected in Hordeum vulgare (barley, Noga cv.) and the plants showed no disease symptoms except for reduced shoot weight. These findings are an important step towards uncovering the host range and endophytic behavior of M. maydis, encouraging expanding this evaluation to other plant species.

Effect of herbicides on feeding, survival and development of Haltica cyanea, a biocontrol agent of dicot weed, Ammania baccifera L. in rice ecosystem

Ammania baccifera L. (Fam: Lathyraceae) is one of the predominant weeds in paddy fields. In nature, the adults and grubs of Haltica cyanea (Coleoptera: Chrysomelidae) feed varaciously on the leaves of this weed leading to drying of the plants. In recent times with the gradual change in cultivation practices and increase in labour shortage the use of weedicides in rice ecosystem has increased tremendously. In an endeavour to explore the possibility of the use of these beetles as biocontrol agents, laboratory studies were carried out at ICAR-IIRR to compare the efficacy of H. cyanea as a biocontrol agent in comparison with the two recommended herbicides and also study the effect of these herbicides on the biology of the beetle. The two recommended herbicides, 2,4-D Na salt 80% (for broadleaved weeds) @800g a.i/ha and Metsulfuron methyl 10% + chlorimuron ethyl 10% WP (for broadleaved and sedges) @4ga.i/ha were tested against A. baccifera and the larval stages of H. cyanea . The effect of these herbicides on survival, feeding, longevity and biology of the bioagent was studied through leaf dip and pot spray method. It was observed that there was 21.67% reduction in shoot weight in beetle released plants as compared to herbicide treatment wherein 38.5-49.3% reduction in shoot weight was observed within 48h. Both the herbicides affected the biology of the insect and between the two herbicides, 2,4-D Na salt was more toxic to the grubs as compared to Metsulfuron methyl + chlorimuron ethyl.

Enantioselective effect of glufosinate on the growth of maize seedlings.

Glufosinate is a non-selective chiral herbicide, which has been used extensively around the world. However,limited information on the enantioselectivity of Rac- and L-glufosinate against crops. In this study, the enantioselective effects on the growth, antioxidant, and targeted enzyme activities of maize seedlings of chiral glufosinate were investigated. The results showed the enantioselective growth inhibitions were observed at both 1 and 5mg/L concentration levels. L-Glufosinate induced more growth rate reduction in shoot height and weight compared to Rac-glufosinate. All of the antioxidant enzyme activities increased obviously in the leaves of maize seedlings treated by 1mg/L of glufosinate. Superoxide dismutase (SOD) activity, catalase (CAT) activity, peroxidase (POD) activity, glutathione reductase (GR) activity, and malondialdehyde (MDA) content induced by L-glufosinate were 1.36, 1.16, 1.51, 1.65, and 1.65 times higher than those by Rac-glufosinate, respectively Notably, the glutamine synthetase (GS) activity was significantly reduced to 80% and 57% in the control group at 1mg/L treated with Rac- and L-glufosinate, respectively. Our results indicated that Rac- and L-glufosinate showed the obvious enantioselectivity in the growth of maize seedlings, which has shed light on the potential enantioselective phytotoxicity of glufosinate. Data provided here will be helpful to develop the environmentally friendly herbicides.

Effect of green, yellow and purple radiation on biomass, photosynthesis, morphology and soluble sugar content of leafy lettuce via spectral wavebands “knock out”

Abstract Spectral composition of artificial light is an important environmental factor for plants cultivated in controllable environment, eg., plant factory. In an attempt to explore the influence of different spectral wavebands on leaf lettuce growth and development, a new way of light treatment with turning off the specific narrow-wavebands from the wide spectrum was established. And leaf lettuce was cultivated under different light spectra with the spectral wavebands of green (LG), yellow (LY) and purple (LP) “knockout” respectively in controllable environment. Then changes in biomass, morphological indexes, photosynthetic gas exchange, chlorophyll content and soluble sugar content of lettuce were examined. Our results revealed that, compared with plants grown under wide-spectral LED light (CK), LG treatment showed significantly reduction of fresh shoot weight at 25 days after planting (DAP) comparing to CK. LY and LP obtained obviously higher fresh shoot weight and moisture content at 15 DAP, in contrast, significantly lower ratio of root to shoot than CK. And A/Ci in LG were significantly reduced by about 33.3% and 36.1% at 20 DAP and 25 DAP respectively compared with CK. In addition, LY showed significant increases in soluble sugar content compared to other treatments at three sampling stages, while the lowest values were obtained in CK. These results indicated that green, yellow and purple light had significant regulations on the biomass, photosynthesis and soluble sugar content in lettuce, depending on the different growth period.