Days After Treatment Research Articles

Transient application of foliar urea with N-(n-Butyl) thiophosphoric triamide on N metabolism of pineapple under controlled condition

Traditional fertilization and the loss of Nitrogen (N) is a common phenomenon in agriculture. Application of urea with urease inhibitor is an alteration measure of urea hydrolysis and N metabolism. Hence, the objective of this study was to determine the short-term foliar application effect of N-(n‑butyl) thiophosphoric triamide (NBPT) on N metabolism, physiological and biochemical changes in the pineapple plant. At 4 month after planting (MAP), 1% urea (Urea) and 1% urea with NBPT (NLU) were applied. Data on urease enzyme activity, internal urea content, inorganic N [ammonium (NH4+) and nitrate (NO3−)], amino acids, total soluble protein, NBPT content, lipid peroxidase (MDA) activity, and electrolyte leakage were recorded for 10 days after treatment (DAT). The results indicated that the NBPT was taken up by the plant, thereby a clear inhibition of the urease activity was observed in pineapple leaf. A higher amount of urea content and a lower amount of NH4+ content in the leaf were the evidence of hydrolysis inhibition by NBPT. Consequently, the contents of amino acid and protein were diminished upon NBPT treatment which demonstrated a change in N metabolism. In addition, amino acid composition demonstrated that amide forms of amino acids were the major components of the decreased amino acid pool. In conclusion, lower MDA activity and electrolyte leakage were also observed under NBPT treated plants indicate that NBPT could release abiotic stress to some extent by protecting the cell wall from damage.

Allelopathic Interference of Weeds on Brown Mustard in Pot Culture

A pot culture experiment was conducted at the Department of Botany, K.N. Government Post Graduate College Gyanpur, Uttar Pradesh coinciding with the Kharif season (July-October) of 2009. The treatments for the growth of test plant T-59 of mustard (Brassica compestris var. dichotoma.) consisted of Aqueous extracts of 4 weeds, viz., Amaranthus viridis, Eclipta alba, Parthenium hysterophorus and Phyllanthus niruri in concentration of 2% (C1 ), 4%(C2 ) and Control (C0 ). Observation on root length, shoot length, leaf area, root biomass and shoot biomass were recorded by harvesting method at an interval of 30, 60 and 90 DAT (days after treatment). Result of the pot culture experiment indicate that the leaf extracts of all the four test weed species, viz.; Amaranthus viridis, Eclipta alba, Parthenium hysterophorus and Phyllanthus niruri had a significant retarding effect on growth of mustard var. T-59 at both C1 and C2 treatment level at all sampling dates (30, 60 and 90 days after treatment). All the test parameters considered in the study, viz., root length, shoot length, total plant length, leaf area, root biomass, shoot biomass and total biomass were found to be significantly affected by weed leaf extracts and such effect was found to be concentration dependant. The net primary productivity (NPP) and relative growth rate (RGR) values were found to be affected by treatment of different concentration of weed leaf extracts of all the test weeds.

Control of common weeds in Wisconsin soybean cropping systems with pre‐emergence herbicides

AbstractThe integration of pre‐emergence (PRE) herbicides is an important component of sustainable long‐term weed management programs in soybean [Glycine max (L.) Merr.]. The objective of this study was to evaluate the efficacy of 11 PRE herbicides on residual weed control in soybean. Field experiments were conducted in 2018 and 2019 at Arlington and Lancaster, WI. Herbicide treatments consisted of imazethapyr, chlorimuron‐ethyl, and cloransulam‐methyl (acetolactate synthase [ALS] inhibitors), metribuzin (photosystem II [PSII] inhibitor), sulfentrazone, flumioxazin, and saflufenacil (protoporphyrinogen oxidase [PPO] inhibitors), acetochlor, S‐metolachlor, dimethenamid‐P, and pyroxasulfone (very long‐chain fatty acid [VLCFA] inhibitors), and a nontreated control. Predominant weed species included common lambsquarters, [Chenopodium album (L.)], common purslane [Portulaca oleracea (L.)], common ragweed [Ambrosia artemisiifolia (L.)], giant foxtail (Setaria faberi Herrm.), waterhemp [Amaranthus tuberculatus (Moq.) J.D. Sauer], and yellow foxtail [Setaria pumila (Poir.) Roem. & Schult.]. Visual weed control was assessed by species and weed biomass across species 65 days after treatment (DAT). The PRE herbicide efficacy varied across site‐years due to the different weed species present at each site. The ALS inhibitors controlled common purslane and common lambsquarters ≥95% 65 DAT at Arlington and Lancaster in 2018 but controlled waterhemp <50% at Lancaster in 2018 and 2019. The PPO inhibitors controlled waterhemp >90% 65 DAT at Lancaster in 2018 and 2019. The VLCFA inhibitors controlled common purslane, common lambsquarters, foxtail species, and waterhemp ≥70% 65 DAT across site‐years but ≤30% common ragweed control at Arlington in 2019. Results showcase the importance of knowing the weed species composition in the seedbank within each field; this can assist growers and crop advisers with selection of the appropriate effective PRE herbicide(s) that matches the weed species composition in each individual field.

Confirmation and Control of Imazamox-Resistant Shattercane

Shattercane is a summer annual grass weed species commonly found in grain sorghum producing regions, including Kansas. Recent development and commercialization of grain sorghum hybrids with tolerance to acetolactate synthase (ALS) and acetyl-CoA-carboxylase (ACCase) inhibiting herbicides will allow producers to use these herbicides for in-season control of shattercane. In a recent field survey, three shattercane populations (DC8, GH4, and PL8) collected from sorghum fields in northwestern Kansas survived the field-use rate (6 fl oz/a) of postemergence (POST) applied IMIFLEX (imazamox). The main objectives of this research were to (1) confirm and characterize the level of resistance to imazamox in those suspected imazamox-resistant (IMI-R) shattercane populations, and (2) determine the effectiveness of alter-native POST herbicides for controlling IMI-R shattercane populations. Imazamox dose-response experiments were conducted in greenhouse conditions at the Kansas State University Agricultural Research Center near Hays, KS. A susceptible shattercane population (SUS) collected from sorghum field in Rooks County, KS, was included for comparison. Dose-response analysis revealed that all three populations exhibited a 3.5- to 5.3-fold resistance to imazamox as compared to SUS population. In a field study, POST treatments of nicosulfuron (Zest), quizalofop (Aggressor), clethodim (Select Max), glyphosate (Roundup PowerMax), and glufosinate (Liberty) provided an excellent control (92 to 100%) of IMI-R population at 21 days after treatment (DAT). These results report the first case of imazamox-resistant shattercane in Kansas. Growers should adopt effective alternative POST herbicides tested in this research for managing IMI-R shattercane.

Safflower (Carthamus Tinctorius L.) Response to Drift Rates of Glyphosate

The paper presented the field studies carried out in Ankara during 2017- 2019 to established the safflower responses (Carthamus tinctorius L. var. Remzibey-05) to drift rates of glyphosate. The herbicide at the rate of 18, 9, 4.5 and 1.44 g active ingredient (a.i.) ha-1 was applied at a spray volume of 19.2 L ha-1 to safflower seedlings at 2-4 true leaf stage using a CO2 pressurized knapsack sprayer. Crop injury and yield reduction caused by the herbicide was determined at 28 days after treatment (DAT) and at harvest. As the drift dose of glyphosate increases, the phytotoxicity occurring in the safflower plant also increases and reached to 68.75-73.75% 28 DAT. Yield reduction caused by the lowest drift rate of glyphosate was limited, 13-25%, compared to the nontreated control. At the highest drift dose, the plants could not produce spike and seeds.

Management of Meloidogyne incognita on Cucumber with a New Nonfumigant Nematicide Fluopimomide.

Cucumber (Cucumis sativus L.) is an economically important vegetable crop in China. Southern root-knot nematode (Meloidogyne incognita) is a significant obstacle in cucumber production, causing severe root damage and yield losses. Moreover, resistance development to fosthiazate, and poor mobility of abamectin, have led to failure to control this nematode. It is of great interest to growers and the vegetable industry to explore novel nonfumigant nematicides that can provide adequate control in an environmentally friendly manner. Fluopimomide (FM), a new chemical having a similar structure to fluopyram, was shown to exhibit toxic effects on fungi and nematodes. The efficacy of FM to reduce infection of M. incognita in cucumber was evaluated under greenhouse and field conditions. In the greenhouse, FM at all test rates resulted in a 22.5 to 39.6% and 31.3 to 55.0% reduction in the population density of M. incognita in the soil at 30 and 60 days after treatment (DAT), respectively, compared with the nontreated control. FM at 500 and 750 g ha-1 reduced (P < 0.05) root galling, meanwhile increasing plant height compared with the nontreated control at 30 and 60 DAT. In the field trials, FM at 500 and 750 g ha-1 decreased the population density of M. incognita and root galling 57.2 to 69.9% compared with the untreated control, while enhancing cucumber yield in two consecutive years. Furthermore, FM at 500 g ha-1 combined with fosthiazate was the most effective treatment showing a synergistic effect on reducing population densities of M. incognita, which was significantly greater than either FM or fosthiazate by themselves. In summary, FM has considerable potential for managing M. incognita on cucumber.

The potential of Central Java local black rice and red rice as drought tolerant cultivars

Black and red rice contain nutritional values not found in white rice. They contain anthocyanins which are beneficial to health. Drought stress can potentially reduce rice yield. So, it is necessary to develop local black and red rice into tolerant cultivars. This study used a completely randomized design (CRD) with cultivar factor (V) and drought stress level (K). Drought stress treatment was carried out when the plants were 35-95 DAP (days after planting) using the modified gravimetric method. Plant destruction was conducted at 7 and 21 DAT (days after treatment) to measure the growth analysis component. The observation of the growth analyses was plant dry weight, leaf area (LA), specific leaf area (SLA), relative growth rate (RGR), and net assimilation rate (NAR). Agronomic characters by observing shoot-root ratio and flowering age. The results showed drought stress decreased plant dry weight, leaf area, and relative growth rate on Sragen black rice. Jelitheng Karanganyar showed high RGR and NAR under drought stress and the fastest flowering age response. Wonogiri black rice gave the growth response by reducing specific leaf area. The highest shoot-root ratio was shown on Wonogiri black rice.

Assure II Alone and with Tacoma and Classic for Efficacy in Fallow

The objective of this trial was to compare Assure II (quizalofop) at two rates with or without tank mix partners for grass control in fallow. Assure II at either rate alone provided similar control of volunteer corn and barley. Corn control was 90% or more regardless of rating date with all herbicides except Assure II at 8.0 oz/a plus Classic (chlorimuron) at 42 days after treatment (DAT). Tacoma (fenoxaprop) at 3.5 or 5.4 oz/a added to Assure II at 8.0 oz/a improved barley control later in the season.

Non-target effects of aqueous leaf extracts of mugwort (&lt;em&gt;Artemisia vulgaris&lt;/em&gt;) and herbicides: Impact on nursery tea plants (&lt;em&gt;Camellia sinensis&lt;/em&gt;)

The weed control potential of Artemisia vulgaris in tea lands has been reported. This study evaluated the non-target effects of the aqueous leaf extracts of A. vulgaris at 25, 50, 75 and 100 g/L (soilapplied, 40 ml/pot) on the growth of 7-months-old nursery tea plants (TRI 4006 and 4046) grown in black polythene bags with 1 kg topsoil. For comparison, commercial herbicides with different modes of action, i.e. Glyphosate, Diuron, MCPA, Pelargonic acid, Pine oil and Glufosinate ammonium, were soil-applied at recommended dosages, with distilled water as the control. Experiments were done in CRD with five replicates, with one plant/replicate. Leaf greenness (SPAD meter) at 20 days after treatment (DAT), visual observations of root growth, and shoot and root dry weights/plant were measured with destructive sampling at 30 DAT. Artemisia leaf extracts did not show significant negative impacts on the aboveground parameters of the tea plant compared to the control. The highest phytotoxicity on nursery tea plants was observed with MCPA (root cell damage; 100% plant mortality). The SPAD readings showed significant leaf chlorosis in TRI 4006 and TRI 4046 with Diuron and Glufosinate ammonium, compared to the control, Artemisia extracts, Pelargonic acid and Pine oil. Poor root growth with lesions was observed with 100 g/L Artemisia leaf extract but at a comparatively low degree to that of herbicides. As the non-target effects of A. vulgaris on tea plants were relatively lower, further studies are warranted to determine an effective dosage for weed control with minimum impact on tea plants and the environment.

Temporal Monitoring and Assessment of Inorganic Nitrogen Content of Soil due to Nitrogen Fertilizers and their Related Cytotoxic Effects

Background: Indian economy is largely based on agriculture. Major share of agricultural investments goes into chemical fertilizers. Nitrogen (N) fertilizers are used in fields to enhance the crop yield. Most of the reports are based on growth related data, morphological and yield related data but very few reports reveal the facts about genotoxic and cytotoxic effects of these fertilizers. Therefore, the present communication is an attempt in the aforesaid direction. Methods: In a pot experiment, mineral N content of soil in the form of ammonium-N (NH4+-N) and nitrate-N (NO3--N) were analysed at regular interval of 5 days till 30 days after treatment (DAT). On the corresponding days root tip assay was done for cytotoxic analyses and also the temporal changes in NH4+-N and NO3--N contents were observed. Result: In the Ammonium nitrate treatments, higher mitotic index (MI%) percentages were obtained. While for the Urea, NH4+-N content and MI were found to have a positive correlation. Also, it was found that there is an optimum ratio of NH4+-N and NO3--N in each treatment at which the MI% was the maximum. The study gives an interesting insight for the possible cytotoxic effects of the N fertilizers.

IN VITRO EVALUATION OF DIFFERENT LOCALLY AVAILABLE PRESERVATIVES AGAINST THE FUNGUS CAUSING TOMATO FRUIT ROT DISEASE

The post-harvest tomato fruit rot caused by Alternaria solani is a major threat to the tomato fruits. Our main objective of this study was to assess the locally available plant based preservatives against post-harvest tomato fruit rot. The in-vitro antifungal effect of 09 different treatments (07 plants based = black pepper, red pepper, turmeric, clove, garlic, onion and papaya seed and 02 chemical preservatives = Potassium metabi-sulphate, PMS and Sodium benzoate, SB) showed significant (P &lt; 0.05 = 0.0000) variation among the treatment groups. Black pepper followed by red pepper and turmeric remained the best antifungal and preservative after 05, 10 and 15 days after treatment (DAT) in B-group (inoculated and uninjured fruits). However, in A-group (inoculated and injured fruits), lowest infection percent was recorded for black pepper followed by red pepper and turmeric after 05, 10 and 15 DAT. The response of all treatments was obvious after 15 DAT. No infection of test fungus was recorded when black pepper and red pepper were applied. Whereas, with the application of turmeric (8.33%) and garlic (9.33%) lowest infection percent was observed with no significant difference. The response of onion (4.33%), papaya seed (6%), clove (7.66%) and SB (15%) appeared moderate with no significant difference. After 30 days, the lowest number of spoilt fruits were recorded with the treatment of black pepper (01) and red pepper (01) followed by turmeric (02), clove (02), onion (02) and SB (02) in B-group. Based on best physical structure, maximum numbers of tomato fruits were observed in clove (04) followed by black pepper (03) and SB (03) when treated without any injury (B group). While in case of A group, almost all fruits in all treatments become spoilt after 30 days of treatment. It has been proved that locally available plant based preservatives have an excellent antifungal and preservative potential against post-harvest tomato fruit rot disease caused by Alternaria solani. These plant based preservatives increase the shelf-life of tomatoes without any health hazards. To the best of our knowledge, this is the first time conducted study, where antifungal and preservative potential of locally available plant products against post-harvest tomato fruit rot caused by Alternaria solani have been explored.

Wood vinegar resulting from the pyrolysis of apple tree branches for annual bluegrass control

Wood vinegar, resulting from the pyrolysis of wood-waste materials, exhibits herbicidal activity against various broadleaf and grass weeds. The objectives of this research were to investigate the composition, property, and efficacy of wood vinegar resulting from the pyrolysis of pruned apple (Malus × domestica Borkh.) tree branches for control of annual bluegrass (Poa annua L.). The composition of wood vinegar was analyzed using gas chromatography-mass spectrometry. Water was the major component in wood vinegar and accounted for 85% by weight. Various organic compounds including acids, alcohols, aldehydes, ketones, phenols, esters, nitrides, and carbohydrate were identified but the major organic compound was acetic acid. Treatments were wood vinegar solutions diluted with distilled water at 0%, 6%, 12%, 25%, 50%, and 100% concentrations. By 20 days after treatment (DAT), when foliarly applied at 2800 L ha−1, the lowest concentration of wood vinegar (6%) only caused 23% annual bluegrass injury, while the highest concentration (100%) caused 95% injury; and the concentration of wood vinegar required to induce 50% visual injury (I50) measured 14%. By 20 DAT, when wood vinegar applied to soil at 110 L m−3, the lowest concentration of wood vinegar (6%) caused 26% visual injury, but the highest concentration of wood vinegar (100%) caused 86% visual injury, and I50 measured 21%. In field experiments, the time required to control 50% annual bluegrass measured 13.3 and 6.6 DAT when wood vinegar concentrations at 50% and 100% applied at 2800 L ha−1. Overall, these results indicate that wood vinegar derived from apple tree branches can be used for controlling annual bluegrass.

Transcriptomic analysis of Allium sativum uncovers putative genes involved in photoperiodic pathway and hormone signaling under long day and short day conditions

Photoperiod is dominant environmental factor that controls plant growth and development. Even though research on plants response to photoperiod is significant in agriculture, molecular mechanisms of garlic in response to photoperiod remain largely unknown. In the current investigation, 3 months old garlic plants were treated with long day (LD) and short day (SD) for 10 and 20 days after treatment (DAT). Liquid chromatography–mass spectrometry (LC–MS) analysis of phytohormones exhibited that indole-3-acetic acid (IAA), zeatin riboside (ZR) and salicylic acid (SA) were observed maximum under LD at 10 DAT, whereas abscisic acid (ABA), gibberellic acid 3 (GA3), zeatin (ZT) and jasmonic acid (JA) were observed maximum under LD at 20 DAT. Transcriptome sequencing analysis was done to evaluate the transcriptional response to LD and SD. Differentially expressed genes (DEGs) were detected to have pathway enrichment. i.e., DNA binding transcription factor activity, transcription regulator activity, transferase activity, transferring hexosyl groups, and sequence specific-DNA binding activity, plant hormone signal transduction, circadian rhythm-plant, biosynthesis of amino acids, phenylpropanoid biosynthesis, and starch and sucrose metabolism. Furthermore, 28 and 40 DEGs were identified related to photoperiod and hormone signaling, respectively and their interaction in response to LD and SD were discussed in detail. Outcomes of current investigation might be useful to provide novel resources for garlic bulb formation in response to photoperiod.

ALLEVIATION OF CHANGES IN GROWTH AND PHYSIOCHEMICAL PARAMETERS IN SALT (NACL) STRESSED OF TWO SESAME (SESAMUM INDICUM L) VARIETIES

Present research was carried out with the aim of identifying effect of salt stress (NaCl 0(Control), 40, 80, and 120 mM) on growth and physiochemical parameters of sesame (Sesamum indicum L.) variety CO-1 and KRR-2. Various parameters such as height of the plant, leaf area, fresh weight of the whole plant and dry weight of whole plant and decreased the content of physiochemical parameters were analyzed. All the parameters were recorded at 30th Days after Treatment (DAT). Analysis revealed a significant reduction in all parameters with increased salt concentration. This experiment carried out fully pot culture methods. Severity of salinity stressed condition were also observed with increased salinity concentration level at the same time decrease in all growth parameter were non-significant in stressed plant as compared two sesame varieties CO-1 and KRR-2. CO-1 in the sesame varieties at 120mM high salt concentration increased with lower decreased was observed in height of the plant, Leaf area, fresh weight of the whole plant and dry weight of whole plant and decreased the content of physiochemical parameters compared to other sesame varieties KRR-2 under salt stress condition. The results indicated that plants of sesame variety CO-1 exhibited higher adaptive potential under salinity stress as judged by higher growth and higher content of physiochemical parameters when compared to variety KRR-2.

Combined effects of cover crops and herbicide rotation as proactive weed management in pineapple (Ananas comosus L. Merr) in Huimanguillo Tabasco, Mexico.

Objective: to evaluate the effect of two proactive strategies for weed management in pineapple, including (1) cover crop rotation and reduced rate of herbicide (RRH) and (2) cover crop association and RRH. Design/Methodology/Approach: We conducted pineapple field experiments in Huimanguillo, Tabasco Mexico, using a complete randomized block design for both rotation and association experiments. Weed occurrence were registered and classified. The weed management effect of cover crops such as cowpea (Vigna unguiculata), sunnhemp (Crotalaria juncea), stylo (Stylozanthes guanensis) and velvet bean (Mucuna pruriens) were evaluated alone and combined with three herbicides. Data of soil ground cover and weed suppression levels were analyzed by one-way ANOVA and the means were separated by Least Significant Differences (LSD) at P = 0.05. Results: Synergistic interaction was detected for weed suppression in all cover crops and herbicide treatments. Combined effects of metribuzin and pendimethalin herbicides with cover crops varied from 80%- 90 % of weed suppression until 90 days after treatment (DAT); however, when cover crops were combined with haloxifop plus diuron, 100 % of weed control was achieved until 90 DAT. Study limitations/implications. Irrigation, weather conditions may affect observations. Findings/Conclusions: Our results showed that all cover crops, specially Vigna unguiculata and Mucuna pruriens in a rotation system, along with reduced rate of herbicides is novel approach strategy for weed management in pineapple plantation. Cover crops such as cowpea might improve crop performance, productivity and feasibility for farmers. The reduced rates of preemergence herbicides and cover crops will be very helpful for the farmers and for protection of environment. Keywords: Cover crops, Anananas comosus, herbicide, weed suppression, integrated weed management

‘Atlantic’ and ‘Dakota Pearl’ chipping potato responses to glyphosate and dicamba simulated drift

AbstractField trials were conducted to determine the effects of glyphosate and/or dicamba simulated drift rates on chipping potatoes (Solanum tuberosum L.) ‘Atlantic’ and ‘Dakota Pearl.’ Sublethal herbicide rates were applied at the tuber initiation stage and consisted of dicamba at 99 g ae ha−1 or glyphosate at 197 g ae ha−1 applied alone or the combinations of dicamba at 20 or 99 g ae ha−1 and glyphosate at 40 or 197 g ae ha−1, respectively. At 7 days after treatment (DAT), the high spray combination of glyphosate plus dicamba resulted in the greatest plant damage (28%). Plant injury from plants treated with the low combination of glyphosate plus dicamba did not differ from the nontreated control. At 21 DAT, visible injury increased to 40% for plants treated with the high combination of glyphosate plus dicamba. Total yield suggested that dicamba and glyphosate caused similar yield reductions as plants that received glyphosate at 197 g ha−1 or dicamba at 99 g ha−1 had lower total yields compared to the nontreated and plants that received the combination of glyphosate (197 g ha−1) and dicamba (99 g ha−1) had lower total yields compared to plants that received either herbicide alone. However, ‘Dakota Pearl’ plants were more sensitive to glyphosate at 197 g ha−1 than were ‘Atlantic’ plants, causing the interaction for most tuber grades. Tuber specific gravity was lower for plants that received glyphosate at 197 g ha−1, dicamba at 99 g ha−1, or this combination, but this reduction would not prevent chip processing. Results reinforce the need for diligence when applying these herbicides in proximity to a susceptible crop, such as chipping potatoes, and the need to thoroughly clean sprayers before application to a sensitive crop.

Long-term effects of water stress on hyperspectral remote sensing indicators in young radiata pine

The development of methods to spatially describe long-term water stress in plantations is going to become increasingly important as drought events increase in frequency under climate change. Despite this we are unaware of any research that has used hyperspectral imagery to describe long-term water stress for the most widely established exotic pine species, Pinus radiata D. Don (radiata pine). Hyperspectral imagery and foliage water content were repeatedly sampled over a five month period in one-year old radiata pine that were allocated to well-watered and drought treatments. These data were used to (i) determine how rapidly equivalent water thickness (EWT) and leaf fresh weight (LWCF) change in response to drought and (ii) identify the key hyperspectral indicators associated with changes in EWT and LWCF.Both EWT and LWCF exhibited little treatment variation until 91 days after treatment (DAT) but diverged strongly after this time. By 108 DAT, mean values in the control exceeded the droughted treatment by 41.3% for EWT (0.0175 vs. 0.0124 g cm−2, P < 0.001) and 17.2% for LWCF (67.7 vs. 57.8%, P < 0.001). Using hyperspectral data captured 108 DAT, highly significant treatment differences (P < 0.001) in reflectance were found in the SWIR region with the most significant differences occurring between 1139 and 2497 nm.There were strong correlations between a wide range of water indices and both measures of water stress using data captured 108 DAT. The indices that were most strongly correlated with EWT were found to be GVMI, NDWI1640 and SIWSI with R2 values ranging from 0.86 to 0.87. Indices that had the strongest correlations with LWCF were SRWI1, GVMI and MSI with R2 values ranging from 0.89 to 0.90. Water indices were more strongly related to both measures of water stress than the physiological index PRI which was moderately correlated to both EWT (R2 = 0.47) and LWCF (R2 = 0.62). A wide range of structural and chlorophyll indices were less well correlated with both measures of water content and long-term water stress than either PRI or the water indices.

Strigolactones affect the root system architecture of cherry rootstock by mediating hormone signaling pathways

Strigolactones (SLs) are new phytohormones that modulate plant root growth and development. Rootstocks affect horticulturally important traits of cultivars, including tree size, abiotic stress tolerance, and disease resistance. This study focused on understanding the effects of SLs on the transcriptional regulation and root system architecture of cherry rootstock. Here, we examined the morphology and profiled endogenous hormone levels, and transcript levels of key genes from the roots treated with synthetic SLs analog GR24 or SLs inhibitor TIS108. Cherry rootstock plantlets treated with 10 μM TIS108 exhibited fewer adventitious roots (AR). The diameter of AR at 5, 10, and 30 days after 0.1 μM GR24 treatment decreased by 23.8, 23.2, and 11.5 %, respectively, whereas AR diameter was 1.15, 1.15, and 1.16 times higher than that in the control when 10 μM TIS108 was applied, respectively. The LR number in plantlets treated with 10 μM TIS108 reached a maximum of 11.25 for each AR, much higher than those of the control and other treatments at 30 days after treatment (DAT). X-ray micro-CT scanning also showed that the treatment with 10 μM TIS108 markedly induced LR initiation but suppressed LR elongation. Furthermore, 2946, 1536, and 2146 differentially expressed genes (DEGs; p-value < 0.05, |log2Fold Change|> 1) were identified in the root samples treated with 0.1 μM GR24, 10 μM GR24, and 10 μM TIS108, respectively, compared to the control. RNA-Seq findings highlighted several DEGs, such as ARF, PP2C, ERF, LOB, and CYC, which play critical roles in hormone signaling, cell cycle, and root growth and development. UPLC-MS analysis further demonstrated that SLs markedly altered the levels of endogenous hormones in cherry rootstock. In particular, the content of endogenous indole-3-acetic acid (IAA) markedly increased by 64.6, 52.1, and 173.5 % after treatment with 0.1 μM GR24, 10 μM GR24, and 10 μM TIS108, respectively. Overall, our study indicates that SLs affect root system architecture by interacting with other plant hormones, which provides a solid theoretical basis for the effects of SLs on the root system architecture of other woody plants.

Field Efficacy of Cordyceps javanica, White Oil and Spinetoram for the Management of the Asian Citrus Psyllid, Diaphorina citri.

Simple SummaryCitrus greening is devastating the citrus industry in Florida, and conventional synthetic pesticide applications are rapidly becoming unsustainable for the control of the vector, the Asian citrus psyllid (AsCP), Diaphorina citri. Laboratory experiments indicate that the entomopathogenic fungus Cordyceps javanica, alone and in combination with horticultural oils, may offer a more sustainable strategy to manage AsCP. The field study in this paper indicated that C. javanica alone, C. javanica mixed with white oil, and spinetoram (the chemical standard) mixed with white oil significantly suppressed AsCP populations by 60–90% and 61–83% 7 and 14 days after treatment, respectively, in 2018, compared to white oil only and the untreated control treatments. Only spinetoram + oil suppressed AsCP 100% up to 7 days after treatment in 2019. AsCP’s natural enemies, mostly lady beetles, were observed on fungal-treated citrus trees and the untreated control. Overall, C. javanica was as effective in suppressing AsCP adults as spinetoram for up to 14 days in field conditions and was compatible with the psyllids’ natural enemies. The use of C. javanica in citrus-integrated pest management is suggested.Citrus greening disease is devastating the citrus industry in Florida, and the conventional synthetic pesticide applications used to control the vector, the Asian citrus psyllid (AsCP), Diaphorina citri, are rapidly becoming unsustainable. Various laboratory experiments indicate that the entomopathogenic fungus Cordyceps javanica, alone and in combination with horticultural oils, may offer a more sustainable strategy for the management of AsCP. Field studies conducted in 2018 and 2019 in mature citrus indicated that C. javanica alone, C. javanica mixed with white oil, and the chemical standard spinetoram mixed with white oil significantly suppressed AsCP adult populations by 61–83% up to 14 days after treatment in 2018, although colony-forming units of C. javanica were still present on the leaves 21 days after treatment (DAT). Only spinetoram + oil significantly suppressed AsCP, by 100%, up to 7 DAT in 2019. Natural enemies of AsCP, including lady beetles, lacewing larvae and the parasitoid Tamarixia radiata, were observed in the fungal treatments and the untreated control. The AsCP suppression by C. javanica and its compatibility with beneficial organisms suggest the potential use of this entomopathogenic fungus in citrus-integrated pest management.

Tolerance of Pima and Upland cotton to trifloxysulfuron (Envoke) herbicide under field conditions

Trifloxysulfuron (Envoke) is an acetolactate synthase-inhibitor herbicide and can be used to control many broadleaf weeds and nutsedges in cotton production. However, there is a lack of information on genotypic variation in response to the herbicide. In this field study, 60 Pima (Gossypium barbadense L.) lines, 122 Upland (G. hirsutum L.) lines, and 9 Upland × Pima segregating populations were divided into five tests (18A, 18B, 18G, 18RB, and 18HQ) to evaluate trifloxysulfuron tolerance at the 7-true leaf stage (42 days after planting) under the same field conditions in 2018. Across the five tests, Pima cotton genotypes tested in this study did not show any visual crop injury based on percentage of plants with chlorosis at 6 days after treatment (DAT), indicating consistent and high levels of trifloxysulfuron tolerance. However, the response to trifloxysulfuron within Upland cotton is highly variable. While Upland cotton is overall more sensitive to trifloxysulfuron with crop injury up to 80% than Pima cotton, 19 lines had injury below 5% including one line with no visual injury, and 19 lines had injury between 5% and 10%. In test 18HQ with 15 transgenic Upland cultivars and 17 non-transgenic Upland lines, the analysis of variance detected a significant genotypic difference. The broad-sense heritability estimates for trifloxysulfuron tolerance based on crop injury at 6 DAT was 0.555, suggesting that trifloxysulfuron tolerance in Upland cotton is moderately heritable. This study represents the first report that Pima cotton and many Upland cotton lines are highly tolerant to trifloxysulfuron with no or little crop injury.