ABSTRACT No information regarding pathogenic variability among different isolates of Ralstonia solanacearum infecting chili from different agro-ecological zones of Pakistan with varying climatic and edaphic factors is available. Therefore, in the present study, variations were observed in biovar distribution, hypersensitive response, growth and virulence among 114 isolates of R. solanacearum collected from eight agro-ecological zones of Pakistan. Out of 114 R. solanacearum isolates, 81% were identified as Biovar III, while the remaining 19% were recognized as Biovar IV. Of all the 114 isolates of R. solanacearum, 77% showed positive hypersensitive response and mucoid growth, while 23% isolates gave negative hypersensitive response with non-mucoid growth. Out of 114 isolates of R. solanacearum consisting of Biovar III and IV, 22.8% were found avirulent, 25.4% weakly virulent, 29.8% virulent, and the remaining 21.9% were highly virulent. Variations among 114 R. solanacearum isolates were also observed in four provinces of the country. Among 92 R. solanacearum Biovar III isolates, 21.7% were identified as avirulent, 25% weakly virulent, 34.4% virulent, and 22.8% were highly virulent in the eight agro-ecological zones of the country. Similarly, out of 22 R. solanacearum Biovar IV isolates, 27.3% were detected as avirulent, weakly virulent and virulent, while 18.2% isolates were found highly virulent. The isolates having non-mucoid growth and negative hypersensitive response were found avriulent, while those with mucoid growth and positive hypersensitive response were weakly virulent to highly virulent. The information will help design control strategies accordingly and develop resistant cultivars against the bacterium.

ABSTRACT The bacterial canker, caused by Xanthomonas citri pv. viticola, is the most important bacterial disease of grapevines cultivated in tropical areas. The objectives of this study were to select grape hybrids resistant to bacterial canker based on genotypic values and to evaluate the response of seedless grape hybrids to artificial infection with bacterial canker. Two experiments were conducted. The field experiment (Experiment I) was conducted with 569 hybrids, evaluated for symptoms of bacterial canker, in the absence of an experimental design, using a single individual of each genotype. Experiment II was conducted in a greenhouse, where ten seedless grape hybrids were evaluated in terms of incubation period, incidence, severity, and area under the progress curve of bacterial canker disease incidence, in a completely randomized design. The use of the residual maximum likelihood/best unbiased linear prediction methodology allowed the selection of 40 grape hybrids with lower genotypic values for resistance to bacterial canker. The CPATSA 49.25 and CPATSA 49.86 hybrids showed greater resistance to bacterial canker in all epidemiological parameters evaluated under greenhouse conditions.

ABSTRACT Tomato is an important economic crop due to its consumption and production worldwide. However, like other crops, it is susceptible to pathogens, being necessary agrochemicals to prevent diseases and improve the production of fruits. Among the sustainable alternatives to crop production, microbial inoculants are used as biofungicide and biostimulants for plant development. Thus, this work aimed to evaluate the biocontrol potential of seven Trichoderma spp. isolates (T1, T2, T3, T4, T15, T17, and T19) against tomato pathogens in vitro experiments, and their potential to improve tomato growth. The Trichoderma spp. antagonism was investigated against Alternaria sp. 003/09, Botrytis sp. 006/13, Fusarium sp. 007/09, and Stemphylium sp. A73. Dual culture, volatile, and diffusible compounds activity tests showed that all new Trichoderma spp. tested could reduce the mycelial growth of all tested pathogens, highlighting T15 and T17 isolates. Seed and soil inoculation revealed very contrasting results: Trichoderma sp. T17 showed a beneficial effect when inoculated in soil, reducing the percentage of yellowish leaves, and increasing dry weight and stem diameter. Inoculation of Trichoderma sp. T17 in the seed increases hypocotyl and radicle lengths, and the seed vigor index. Finally, the strains studied present the potential to be used to develop biocontrol products.

ABSTRACT This study aimed to model nutrient losses in an Oxisol under varied soil properties and vegetation cover. The experimental area was located at the Paraná Rural Development Institute, in Santa Tereza do Oeste, Paraná, Brazil. The treatments consisted of six cover crops in summer, six cover crops in winter, and management systems no-tillage (NT) traditional (control), NT with gypsum, and NT with scarification. Nutrient data were collected at each natural rainfall through sample collection from collection troughs. The design was completely randomized, and the data were adjusted using an exponential function of two variables, as a function of soil density, macroporosity, straw dry mass, green cover, and rainfall. Greater losses of Mg and Ca was related to higher soil density and lower macroporosity. Lower losses of Mg, Ca, K, and P were associated with lower straw dry mass and higher green cover. K and P losses were stable for all soil density values, but they decreased with an increase in macroporosity.

ABSTRACT The search for bioherbicides has been encouraged, and plants used in food or with bioactivity have been studied. Therefore, this article aimed to investigate the bioherbicidal potential of essential oils from Psidium cauliflorum and P. acidum through a plant toxicity bioassay using Lactuca sativa and Sorghum bicolor. The seeds were treated with essential oils of both species, along with control groups treated with distilled water, dichloromethane, and glyphosate. Germination percentage (GP), germination speed index (GSI), root growth (RG), shoot length (SL), mitotic index (MI), chromosomal alterations (CA), and nuclear alterations (NA) were evaluated. The major compound of the essential oil of P. cauliflorum was α-pinene, and of P. acidum were trans-caryophyllene, β-elemene, germacrene A, and α-copaene. The essential oils from both species exhibited phytotoxic effects. P. acidum oil inhibited sorghum RG and lettuce SL, while P. cauliflorum oil reduced GP, GSI, RG, and SL in both plants, indicating higher phytotoxicity than P. acidum and non-selective behavior. Cytotoxic investigations showed that both oils inhibited the MI. CA analysis revealed that P. cauliflorum oil exhibited aneugenic and clastogenic action mechanisms. The results demonstrate the bioherbicidal potential of P. cauliflorum essential oil, in addition to being non-selective and displaying a similar inhibition rate to glyphosate.

ABSTRACT Integrated nutrient management (INM) is an environment friendly and ecologically adoptable approach of plant nutrition to sustain crop productivity and maintain soil fertility of fragile agricultural ecosystems. A three-year field experiment on saffron was conducted involving 12 fertilization regimes: control; urea (UN) = 100 kg·ha-1; poultry manure (PM) = 100 kg·ha-1; farmyard manure (FYM) = 100 kg·ha-1; PM50 + FYM50; UN75 + PM25; UN50 + PM50; UN25 + PM75; UN75 + FYM25; UN50 + FYM50; UN25 + FYM75; and UN50 + PM25+ FYM25. Results showed that PM alone and combined with 50% UN (UN50 + PM50) were effective compared to the controls in increasing the number of flowers (58%), flower dry weight (59%), stigma length (70%), dry weight of stigma (40%), number of daughter corms plant-1 (35%), and corm diameter (71%) of saffron over years. In addition, the same treatment combination increased corm weight (96%), corm yield (96%), and stigma yield (35%) over controls across the years. This treatment combination was followed by UN50 + PM25 + FYM25, while UN50 alone did not perform at par to the rest of the fertilization regimes. These results showed that UN50 + PM50 might be developed as potent strategy for boosting the growth and yield (stigma and daughter corms yield) of saffron in temperate climatic conditions.

ABSTRACT The objectives of this work were to use Sesuvium verrucosum to produce stable and mature compost and vermicompost and to evaluate their influence on the growth and production parameters of the Solanum lycopersicum L. crop. For the preparation of vermicompost, the earthworm Eisenia fetida (Savigny) was used. The proposed treatments were: T1 (negative control) [no organic fertilizer + urea], T2 (positive control) [bovine manure (100%) + urea], T3 (compost) [bovine manure (100%) + urea], T4 (compost) [S. verrucosum (25%) + bovine manure (75%) + urea], T5 (compost) [S. verrucosum (50%) + bovine manure (50%) + urea], T6 (compost) [S. verrucosum (75%) + bovine manure (25%) + urea], T7 (vermicompost) [bovine manure (100%) + urea], and T8 (vermicompost) [S. verrucosum (25%) + bovine manure (75%) + urea]. The results showed that all the treatments were stable, mature and rich in nutrients after 140 days. In general, treatments made from S. verrucosum showed a high pH (7.97–8.45) and electrical conductivity (3.83–8.85 dS m-1). Nonetheless, excluding T7, the treatments made from a proportion of 25% halophyte and 75% bovine manure (T8 and T4) achieved the highest morphological parameters in the different variables that were evaluated, as well as the highest yields compared to controls T1 and T2, followed by T3, T5 and T6, respectively. Therefore, it was concluded that S. verrucosum can serve as a stable and mature organic amendment, rich in nutrients, and that can be used to improve the growth and development of the S. lycopersicum crop.

ABSTRACT The aim of this study was to select pear cultivars with production stability for the environmental conditions in the tropics. The design was in randomized blocks with 11 cultivars of pear, four replications and plots consisting of four plants. Between 2015 and 2019, the phenological were evaluated based on the beginning, full bloom, end and duration of flowering and harvest. The number and average fruit mass, yield per plant and estimated yield were also quantified. In the last year of evaluation, the quality of the fruits was quantified through the length and average diameter of the fruits, total titratable acidity, total soluble solids content and total soluble solids / total titratable acidity ratio. The data were submitted to the Scott–Knott grouping test and to quantify the divergence between cultivars was used the genetic distance. After detecting significant interaction between genotypes × environments, phenotypic stability of pear cultivars were analyzed by GGE Biplot methods for the estimated yield variable. The ‘Tenra’, ‘Triunfo’ and ‘Seleta’ cultivars are the most suitable for cultivation in regions with subtropical altitude climate. They are genetically similar, more adapted and stable, and have full or partial synchronized flowering for satisfactory productivity.

ABSTRACT The production of chili is seriously threatened by bacterial wilt incited by Ralstonia solanacearum in Pakistan. As the information about the distribution and prevalence of the disease and the pathogen is scarce, the present study was performed to ascertain the prevalence, occurrence and distribution of R. solanacearum in different regions of chili cultivation. The results showed differences in the incidence and prevalence of bacterial wilt all over the country. Overall, an incidence of 10% and prevalence of 76% of the disease was observed in the country. The highest incidence of bacterial wilt was observed in the province of Sindh whereas it was the lowest in Baluchistan. The prevalence of the disease followed the similar trend in the provinces. As regards agroecological zones, the highest incidence was recorded in Indus delta followed by sandy deserts whereas it was the lowest in western dry mountains. Almost the same tendency was observed regarding prevalence in the eight agroecological zones. In case of districts, the disease incidence was the maximum in Badin while it was the minimum in the district of Loralai. On the other hand, the disease prevalence was the maximum (100%) in the districts of Badin, Mirpurkhas, and Thatta and the minimum (60%) in the districts of Barkhan, Karak, and Loralai. Of the total 114 isolates of R. solanacearum, 81% were confirmed as Biovar 3 whereas the rest 19% isolates were identified as Biovar 4. The findings will help the farmers to design disease management programs accordingly to avert yield losses.

ABSTRACT The decoupling factor (Ω) reflects the leading mechanisms responsible for canopy transpiration and allows to know the relevance of the control of stomatal or canopy conductance on transpiration (T). The Ω is strongly dependent on water availability and can be a good approach to describe how plants minimize excessive water loss by increasing the dominance of biotic factors that controls evapotranspiration under water deficit conditions. We provided an overview of how the Ω concept can be broadly used and applied for studying the sensitivity of evapotranspiration and water conservation potential of canopies under water deficit conditions. A decoupling condition indicates that, under water deficit, the increase of canopy resistance will not have control over the transpiration. Therefore, a structural context of the canopy in which predominantly uncoupled regions will have a lower capacity to reduce evapotranspiration and avoid water losses. Furthermore, because of the water deficit, stomatal closure restricts photosynthesis more than transpiration, and water use efficiency can be lower in decoupled canopies compared to more coupled ones. Yet, we summarized the characteristics that depict structural context predisposing coupled or decoupled conditions that can indicate the capacity of canopy/crop to reduce excessive water losses and maintain a high assimilation/transpiration relation under water deficit.e farmers to design disease management programs accordingly to avert yield losses.

ABSTRACT Isoflavonoid composition of freshly harvested soy sprouts of six cultivars grown in Colombia was analyzed. Evaluations on the effect of storage time at 12 °C and exogenous application of the elicitor 2,6-dichloro isonicotinic acid (INA) were carried out to establish their influence in the ability of soy sprouts for synthesizing isoflavonoids. In addition, elicited and non-elicited sprouts of soy cultivar Soy SK-7 was assessed for total phenolic content and antioxidant activity according to the growth stage (VE, VC, and V1) and tissues (cotyledon-epicotyl and hypocotyl-root). Isoflavonoid content and antioxidant capacity were dependent on the cultivar, growth stage, tissue, and storage time at 12 °C. Growth stages VE and V1 and the hypocotyl-root exhibited the highest total phenolic content and antioxidant activity. In general, 6”-O-malonylgenistin, daidzin and genistin were the major constituents in the cultivars. Soy SK-7 and Panorama 358 displayed the highest amounts of 6”-O-malonylgenistin (155.9 µg/g) and daidzin (83.5 µg/g), respectively. Results showed that the isoflavonoids and phenolic contents and antioxidant activity were significantly increased by application of INA. This information can be useful to produce soybean sprouts with increased amounts of bioactive compounds and improved response to abiotic and biotic stresses.

ABSTRACT Ryegrass and turnip are weeds that cause high yield losses when infesting barley, thus requiring adequate management. In this context, the aim of this study was to evaluate the selectivity of different herbicide treatments and weed control in the barley crop, cultivar BRS Cauê. Two field experiments were conducted in randomized blocks, with four replications. The treatments used were: pendimethalin (800 g·ha-1), sulfentrazone + diuron (175 + 350 g·ha-1), and imazaquim (150 g·ha-1 of a. e.) applied pre-emergence; and iodosulfuron (3.5 g·ha-1), pyroxsulam (18 g·ha-1), metsulfuron-methyl (3.96 g·ha-1), 2,4-D (670 g·ha-1 of a. e.), clodinafop-propargyl (48 g·ha-1), bentazon + imazamox (600 + 28 g·ha-1), saflufenacil (49 g·ha-1), bentazon (720 g·ha-1), carfentrazone-ethyl (120 g·ha-1), and imazamox (42 g·ha-1) applied post-emergence, with two controls (one weeded and the other infested). The use of the herbicide imazaquim caused high levels of phytotoxicity in barley. Gas exchange was less responsive to herbicide applications in relation to barley phytotoxicity and productivity. Clodinafop-propargil showed the best control of ryegrass, while the herbicides iodosulfuron, pyroxsulam, metsulfurom-methyl, 2,4-D, bentazon + imazamox, saflufenacil, bentazon, carfentrazone-ethyl, and imazaquim showed high efficiency in the control of turnip species. Imazaquim caused reduction of up to 74.7% in barley grain yield. On the other hand, iodosulufuron and piroxsulam allowed the highest grain yields of the barley cultivar, BRS Cauê, by promoting partial control of ryegrass and total control of turnip species, followed by clodinafop-propargyl and metsulfuron-methyl, which controlled ryegrass and turnip, respectively, allowing an increase in yield grain in relation to the infested control.

ABSTRACT Hydroponic is a technique of growing plants in a soilless medium by using a sponge, rock wool, hydroton, coconut coir, and perlite as an alternative for crop production systems. Recently, biochar has been reported to be a potential substrate for hydroponic cultivation techniques due to its physicochemical properties which can help increase vegetable production. A greenhouse study was conducted to investigate the effect of biochar as hydroponic substrate on the growth, colour and nutritional content of red lettuce (Lactuca sativa L.). This study utilized the nutrient film technique (NFT) hydroponic system and was conducted using a randomized complete block design with five treatments, including T1 (hydroton only), T2 (perlite only), T3 (palm kernel biochar), T4 (palm kernel biochar + hydroton), and T5 (palm kernel biochar + perlite). Data analysis revealed the treatment, which consists of both palm kernel biochar and hydroton (T4) resulted in a significant increase in plant growth and yielded the highest plant height (19.86 cm), leaf width (14.16 cm), plant fresh weight (68.19 g), and dry weight (8.29 g). The leaves nutrient content (N, P, K, Mg, Ca) of red lettuce grown in palm kernel biochar and hydroton (T4) substrates suggested the presence of optimal growth conditions for ensuring optimum yield with high quality. The application of palm kernel biochar and hydroton (T4) as substrate also showed a higher lightness value (L* = 66.67). Besides, the methanolic leaf extracts from the red lettuce grown in palm kernel biochar and hydroton (T4) showed the highest bioactive metabolite content. In addition, the application of palm kernel biochar (T3) as a hydroponic substrate decreased the algal density in the nutrient solution. In conclusion, the combination of palm kernel biochar and hydroton as a substrate was observed to be the best in enhancing the growth performance, colour, and nutritional content of red lettuce (Lactuca sativa L.), and it is therefore recommended to be used as the growth substrate in the NFT system.

ABSTRACT Identifying Coffea arabica cultivars that are more efficient in the use of nitrogen is an important strategy and a necessity in the context of environmental and economic impacts attributed to excessive nitrogen fertilization. Although Coffea arabica breeding data have a multi-trait structure, they are often analyzed under a single trait structure. Thus, the objectives of this study were to use a Bayesian multitrait model, to estimate heritability in the broad sense, and to select arabica coffee cultivars with better genetic potential (desirable agronomic traits) in nitrogen-restricted cultivation. The experiment was carried out in a greenhouse with 20 arabica coffee cultivars grown in a nutrient solution with low-nitrogen content (1.5 mM). The experimental design used was in randomized blocks with three replications. Six agromorphological traits of the arabica coffee breeding program and five nutritional efficiency indices were used. The Markov Chain Monte Carlo algorithm was used to estimate genetic parameters and genetic values. The agromorphological traits were considered highly heritable, with a credibility interval (95% probability): H2 = 0.9538 – 5.89E-01. The Bayesian multitrait model presents an adequate strategy for the genetic improvement of arabica coffee grown in low-nitrogen concentrations. Coffee arabica cultivars Icatu Precoce 3282, Icatu Vermelho IAC 4045, Acaiá Cerrado MG 1474, Tupi IAC 1669-33, Catucaí 785/15, Caturra Vermelho and Obatã IAC 1669/20 demonstrated greater potential for cultivation in low-nitrogen concentration.

ABSTRACT Nanoparticles have been widely used in recent years, to increase plant tolerance under stress conditions. In this study, TiO2 nanoparticles (NPs) (100 ppm) were applied to tomato plants exposed to drought, and the changes were investigated by physiological, biochemical and proteomic methods. It was determined that TiO2 NPs treatment increased the relative water content and decreased the proline and malondialdehyde content under drought conditions. As a result of proteomic analysis, it was revealed that the expression of a total of 132 proteins changed as a result of the comparison of the treatment groups (drought vs. control, control-100 vs. control, and drought-100 vs. drought). One of the most striking results of the study was the increase of the amounts of photosynthesis-related proteins and plasmamembrane intrinsic protein in both drought and control groups with TiO2 NP-treatmtent. The up-regulation of plasmamembrane intrinsic protein is very important for preserving the water potential under drought conditions. Taken together, it was observed that the water potential of the plant was preserved, lipid peroxidation decreased under drought conditions with the application of TiO2 nanoparticles, and the expression of proteins related to photosynthesis, energy and antioxidant system increased. This study provided clues to the molecular mechanism of the results of many studies available in the literature about nanoparticle treatment under stress condition and showed that TiO2 nanoparticles have a great potential to be used to increase the stress tolerance of tomato plants under drought conditions.