Potassium (K) performs multiple essential functions in the plant, including enzyme activation and osmotic regulation. Citrus fruit quality gains considerable influence from potassium (K) fertilizer rate, application method, and sources used. The conducted field experiment assessed the impact and response of different levels of K applications on the quality and yield parameters of citrus fruit, determining a suitable time, stage, and K fertilizer dose for citrus trees. Comparing traditional K fertilizer, i.e., sulfate of potash (SOP), with new-generation potassium (NG-K) employed the use of foliar and soil (basal) applications. Treatments included (i) T1: Control (0 NPK), (ii) T2: Recommended NP and without K, (iii) T3: 500 g K as sulfate of potash (SOP) (basal), (iv) T4: New generation K (NG-K) fertilizer @1.5% (foliar), and (v) T5: 400 g NG-K fertilizer (basal). Observations revealed that citrus trees responded positively in growth characteristics, including fruit quality and physiological attributes, under both foliar and basal K fertilizer applications of different K sources. Notably, NG-K fertilizer proved a better source of K, whether applied as a basal dose or foliar spray. For growth characteristics like the fresh weight of leaves and fruit mass, obtaining the highest values of 35.2 and 172 g, respectively, resulted when applying a basal dose of NG-K. On the other hand, maximum total sugar content (13 mg L^-1) and juice content (40%) occurred under foliar-applied NG-K. Foliar application of K fertilizer proved to be more effective for better growth and fruit quality parameters than the basal application of SOP.

Keywords: Citrus, growth characteristics, potassium, fertilizer, formulation

Key findings: K fertilizer application improved the citrus fruits’ quality and quantity attributes irrespective of source, dose, and application method. However, among K fertilizer sources, newgeneration K fertilizers proved superior over commercial K sources (SOP). Regarding the application method, the foliar application gave better results and effectively improved the quality and growth attributes of the citrus fruits.

The tendency to use natural organic wastes is one of the environmentally safe applications in crop production. Therefore, the presented study aimed to determine the effect of adding mushroom and sulfur residues to gypsiferous soil and their efficiency in improving the production of broccoli ‘Balimo F1’ (Brassica oleracea var. ‘Italica’). The study set out in a randomized complete block design with three replications. The 10 combined treatments of the spent mushroom substrate (SMS) and sulfur residues consisted of 0% and 15% (SMS), and 0, 1000, 2000, 3000, and 4000 S kg ha^-1. The interaction of the spent mushroom substrate with sulfur showed significant differences for most growth and yield-related traits of broccoli, including leaf length, leaves per plant, roots per plant, head diameter, head weight, total yield, and harvest index, as compared with the control treatments. Among all the treatments in broccoli, the highest total yield (148,702 kg ha^-1) resulted in the treatment SMS – 15% + Sulfur – 3000 kg ha^-1, followed by the total yields of 111,608 and 105,663 kg ha^-1 produced by the treatments SMS – 15% + Sulfur – 4000 kg ha^-1 and SMS – 15% + Sulfur – 2000 kg ha^-1, respectively. However, the minimum total yield in broccoli (28,295 kg ha^-1) came from the treatment SMS – 0% + Sulfur – 3000 kg ha^-1, followed by a total yield of 33,793 kg ha^-1 obtained in the treatment SMS – 0% + Sulfur – 4000 kg ha^-1. Overall, and compared with the control, a significant influence occurred due to the interaction of spent mushroom substrate and sulfur with levels of 15% and 3000 kg ha^-1, respectively.

Keywords: Broccoli, spent mushroom substrate (SMS), composting, sulfur, inorganic fertilizer, organic manure, gypsiferous soil

Key findings: For growth and yield-related traits of broccoli, a significant influence occurred due to the interaction of spent mushroom substrate (SMS) and sulfur at the levels of 15% and 3000 kg ha^-1, respectively.

Phosphate-solubilizing and nitrogen-fixing bacteria are crucial in increasing soil fertility and restoring soil properties damaged by salinity and other abiotic environmental factors. The presented study aims to explore and identify the morphological characteristics of phosphate-solubilizing and nitrogen-fixing bacteria in saline soil. This study took place from August until November 2022 in the field and laboratory of the Faculty of Agriculture, Universitas Muhammadiyah Sumatera Utara, Medan, Indonesia. Isolation of potential microbes proceeded to characterize phosphate-solubilizing and nitrogen-fixing bacteria. Sampling began with the soil planted with rice and palm oil at the sampling location. Morphological parameters observed were color, form, margin, surface, and elevation of pure colonies. The result showed that exploring various species in saline soil revealed 19 colonies and 14 cells of phosphate-solubilizing bacteria and 16 colonies and 14 cells of nitrogen-fixing bacteria. The pure colonies of the phosphate-solubilizing and nitrogen-fixing bacteria showed differences in the morphological characteristics, i.e., color, form, margin, surface, and elevation. The potential microbes obtained sought to increase soil fertility and crop production.

Keywords: Phosphate-solubilizing bacteria, nitrogen-fixing bacteria, morphological characteristics, saline soil

Key findings: Exploration and identification of morphological characteristics is a must action to analyze potential microbes in depth to improve the quality of saline soils to increase crop productivity.

Shallot production has many challenges, including the anthracnose disease caused by the pathogen Colletotrichum gloeosporioides Penz. Disease characteristics include severe twisting of leaves, neck elongation, and necrosis of leaves. This disease can cause yield loss of up to 100 percent. In addition to chemical control practices, resistant shallot varieties will be very useful in decreasing losses. However, information about existing shallot varieties resistant to C. gloeosporioides is limited. The study objectives are to identify the shallot varieties resistant to C. gloeosporioides and identify morphological characters and secondary metabolites of the leaves that may associate with the defense mechanism in shallot. Fourteen shallot varieties underwent a single factor use in a randomized block design in the field and laboratory experiments. The experiment transpired from January to June 2021. Planting healthy shallot bulbs of all genotypes in a polybag containing sterile media continued by artificial inoculation of C. gloeosporioides after the plant had 3–5 leaves. The field test showed that the Sumenep variety has the best resistant level to C. gloeosporioides, with a disease severity score of about 30.19%. On the other hand, the Blue Lancor variety is most susceptible, with a disease severity score reaching 95.05%. The study also found an indication that a possible resistance of shallots to C. gloeosporioides relates to the thickness of the palisade tissue (r =-0.8, P < 0.001), with the induced mechanism associated with the detection of the presence and increase of carbamic acid concentrations.

Keywords: Carbamic acid, defense mechanism, palisade tissue, secondary metabolite, Sumenep variety

Key findings: Identifying the resistance of leaf cellular morphology showed that palisade tissue is a character associated with shallot resistance to C. gloeosporioides.

Currently, the selection of tomatoes with a high content of biologically active substances and antioxidant properties at the large green and breaker stage is relevant since mature tomatoes cannot tolerate storage and transportation. For this purpose, 11 tomato genotypes, chosen in a preliminary study in 2018–2020 from the Genetic Collection of Plant Resources of Federal State Budgetary Scientific Institution Federal Scientific Vegetable Center (FSBSI FSVC), Moscow, Russia, and Tomato Genetics Resource Center (TGRC), the University of California, Davis, USA, for further studies during 2020–2022 for antioxidant pool changes: measuring the contents of chlorophyll, lycopene, β-carotene, ascorbic acid, and lutein. The experiment arranged in a randomized complete block design proceeded in the film unheated greenhouses. The results showed five promising tomato genotypes, i.e., VFN Hi Sugar, VS-420, Paul Robeson, Black Cherry, and VS-410. The genotype Black Cherry fruits with breaker ripeness contained 42% lycopene and 93% β-carotene, while the genotype Paul Robeson at the same stage contained 80% β-carotene. The three other tomato genotypes, viz., VFN Hi Sugar, VS-420, and Paul Robeson, also gave a higher content of ascorbic acid in the fruits at the breaker ripening stage.

Keywords: Tomato, ascorbic acid, β-carotene, chlorophyll, lutein, lycopene, total phenols

Key findings: The studied dynamics of various pigments with biological activity according to the tomato ripening stages revealed promising genotypes identified and selected for further studies.

The present study aimed to determine the genetic divergence of seven maize genotypes (Al-Maha, Sumer, Al-Fajr, Baghdad, 5018, 4 × 1 single hybrid, and 4 × 2 single hybrid) under two varied levels of nitrogen fertilization (92 and 276 kg N ha^-1). The experiment occurred in 2022 in a randomized complete block design (RCBD) with a split-plot arrangement and three replications at the College of Agricultural Engineering Sciences, University of Baghdad, Iraq. The nitrogen fertilization levels served as main plots, with the maize genotypes allocated as the subplots. The results revealed that genetic variance was higher than the environmental variance for most traits, and the coefficient of phenotypic variation was close to the genetic variation coefficient under the two levels of nitrogen fertilization. Heritability (broad sense) at the 92 kg N ha^-1 (N1 level) was the highest for traits. i.e., ear height, grains per row, grains per ear, individual plant yield, yield per unit area, days to 50% male flowering, leaf area, ear length, rows per ear, and 100-grain weight, with values of 92.556%, 90.760%, 90.123%, 95.007%, 95.007%, 88.976%, 89.974%, 88.748%, 85.521%, and 89.690%, respectively. For the N level of 276 kg ha^-1 (N2 level), the heritability in a broad sense was high for the traits, viz., days to 50% male flowering (91.546%), plant height (96.150%), ear height (91.038%), ear length (92.454%), individual plant yield (98.108%), yield in the unit area (98.108%), and plant dry weight (85.488%). The cluster analysis divided the maize genotypes into four and five cluster groups under the nitrogen fertilization level of 92 and 276 kg N ha^-1, respectively. These different groups of maize genotypes could be due to the genetic divergence among the genotypes resulting from their varied genetic makeup and origin.

Keywords: Maize (Zea mays L.), genetic diversity, nitrogen fertilization levels, heritability, broad sense, cluster analysis, yield related traits

Key findings: The presented study can identify the genetically diverged maize genotypes with some other genetic parameters, which could benefit hybridization for transferring better yield-related genes to improve grain yield through various breeding methods.

Five rice (Oryza sativa L.) cultivars (N22, Amber, Moroberekan, Kinandang Patong, and Azucena) underwent path coefficient analysis across three plant spacings (15 cm × 15 cm, 20 cm × 20 cm, and 25 cm× 25 cm) in the summer of 2017 at the College of Agricultural Engineering Sciences, University of Baghdad, Al-Jadriya, Iraq. The experiment proceeded in a randomized complete block design (RCBD) with a split-plot arrangement and three replications. The main plots included three planting distances, and the subplot comprised five varieties. The traits studied were plant height, flag leaf area, number of tillers, panicle number, length and branches, grains per panicle, 1000-grain weight, and the percentage of unfilled grains. The results showed significant (P ≤ 0.05) differences between direct and indirect and total effects. The studied traits provided negative values for the total effects except for the number of tillers and the number of panicles per plant, as these two traits reached 1.0938 and 1.0798, respectively. With the second plant spacing of 20 cm × 20 cm, the traits: plant height, number of tillers, number of panicles, and panicle length, showed the total positive effects, ranging from 0.2803 to 0.6606, with the remaining traits enunciated negative values. For the third plant spacing of 25 cm × 25 cm, the traits: panicle length, number of tillers, grains per panicle, and 1000- grain weight, exhibited positive values for the total effects, ranging from 0.623 to 1.1593.

Keywords: Rice (Oryza sativa L.), path coefficient analysis, correlation coefficient, genetic variability, plant spacing, morphological and yield-related traits, grain yield

Key findings: Significant variations among direct and indirect effects of various rice traits indicate that the panicle length, number of tillers, grains per panicle, and 1000-grain weight with a plant spacing of 25 cm × 25 cm could serve as vital selection criteria for improving the grain yield in rice.

Selected agronomic traits are the conventional approach to evaluating corn plantings. However, this approach is only some-encompassing for planting plots; hence, needing a more precise method for the evaluation. Unmanned aerial vehicles (UAVs) or drones are precision technologies that provide detailed information regarding cropping status through image analysis to make the assessment and prediction process more efficient. Therefore, using agronomic traits and drones together is a necessary approach to take. Presented research aimed to develop a productivity prediction model based on selective and precision secondary characters. The experiment happened from September to December 2021 in Tarowang Village, Takalar Regency, South Sulawesi, Indonesia. Eight maize cultivars, i.e., ADV1, Pioneer 1, Pioneer 2, NK, Bisi 18, Sinhas 1, NASA 29, and ADV2, grown and evaluated in a randomized completely block design with three replications, served as the main factor. Based on the results, the weight of 1000 grains, was a recommended agronomic trait in the evaluation and prediction of corn planting. In addition, normalized difference vegetation index (NDVI)-UAV, as part of ‘Technology 4.0’, considerably showed effectiveness in predicting maize productivity. Meanwhile, combining two variables notably have the highest accuracy in predicting corn productivity compared with their independent predictions. However, the advanced research still needs optimizing by using more maize genotypes and locations to increase the accuracy and forecast of the model.

Keywords: Agronomic traits, multivariate regression, NDVI, Technology 4.0, Zea mays

Key findings: Combining a selective agronomic trait (weight of 1000 grain) and NDVI-UAV revealed more effectiveness in evaluating the maize genotypes. This combined strategy can enhance the accuracy and precision of corn yield prediction. The multiple regression formulation from combining the two characters was 17.0486 NDVI + 0.038 weight of 1000 grain – 20.244. Moreover, the maize cultivar NK-7328 proved to be the best for cultivation in Takalar Region, Indonesia.

Zinc deficiency in cereal crops is a significant issue for human health. Rice, being a staple food crop, could cause severe zinc deficiency. The use of zinc-solubilizing bacteria (ZSB) is an ecological tactic to raise bioavailable zinc in the soil that may alleviate yield loss and, subsequently, enhance the nutritional value of rice. In the presented study, treating rice plants with plant growth-promoting rhizobacteria S. marcescens FA-4 along with the recommended dose of chemical Zn and half dose of chemical Zn ensued under pot and field conditions at the COMSATS University, Islamabad, Pakistan. The obtained data indicated an augmentation in rice growth, yield, and grain zinc content in response to the S. marcescens FA-4 inoculation with and without the chemical Zn application. The S. marcescens FA-4 significantly enhanced the grain zinc content (21.4–27.7 mg kg^-1) under the pot and (18.7–30.1 mg kg^-1) under field conditions, with 1.5 to twofold rise in superoxide dismutase (SOD) and carbonic anhydrase (CA) activity in rice compared with the control. The rice plants treated with zinc solubilizing bacteria, followed by zinc treatments gave higher grain yields of 23.4–34.1 g pot^-1 and 3.2–3.6 t ha⁻¹ in rice cultivars, Basmati 385 and Super Basmati. The S. marcescens FA-4 with a half dose of chemical Zn also increased the zinc translocation index (1.4 to 1.7) toward grains. Consistency in the performance of zinc solubilizing bacteria occurred in the pot and field conditions. Hence, a conclusion that the use of zinc solubilizing strains is an efficient approach to enhance the zinc content of rice grains and combat the problem of zinc deficiency in humans.

Keywords: Zinc-solubilizing bacteria, superoxide dismutase, carbonic anhydrase, grain zinc content, rice

Key findings: The rice growth and yield increased in response to the combination of zinc solubilizing Serratia marcescens FA-4 and half a dose of chemical Zn. The Serratia marcescens FA-4 significantly enhanced the grain zinc content under the pot and field conditions, causing a 1.5 to twofold rise in superoxide dismutase (SOD) and carbonic anhydrase (CA) activity in rice compared with the control.

Phenotypic and genotypic diversity is essential and needs more enhancement in different ways to achieve higher productivity and better quality vegetables. The presented research aimed to study the phenotypic characteristics and determine the genetic diversity of F₁ populations compared with the colchicine mutant variants in the Mercy cultivar of cucumber (Cucumis sativus L.), held from March to May 2019 at the experimental field of the Department of Agrotechnology, Islamic University of Riau, Pekanbaru, Indonesia. A total number of 144 studied plants comprised 72 from each of the two plant groups. The data recorded on various parameters attained statistical analysis using paired T-test at a significant P < 0.05. Comparisons between the cucumber plants of both groups included karyotypes and chromosome shapes, idiograms, and sequencing. The results revealed that, on average, the taller plants came from F1 populations (93.49 cm), followed by mutants of the same cultivar (67.83 cm). The F₁ hybrids showed early flowering (29.00 days) compared with colchicine-treated mutants (33.31 days). However, the number of fruits and fruit weight were higher in the mutant variants (9.39 fruits and 1055.39 g), followed by F₁ populations. The karyotypes of cucumber cultivar Mercy F₁ hybrids and mutants have different chromosomes, especially with the arm size. An idiogram also exhibited differences in chromosome length between the variants of both plant groups, while the primers of trnL-F and trnL-R target sequences were the same with the DNA sequence length. Using mutant cucumber seeds demonstrates a change in phenotypic character to increase fruit production. However, polyploidy did not occur, with genetic alterations measured by the length of chromosome arms. As a result, a future study with increased concentrations of colchicine is imperative to obtain significant chromosomal mutations.

Keywords: Cucumber (Cucumis sativus L.), F₁ hybrids, colchicine mutants, growth traits, phenotypic characteristics, genetic diversity, chromosomes

Key findings: The number of fruits and fruit weight were higher in the mutant populations, while the Brix values and plant height were better in F₁ hybrids compared with the mutants in cucumber (Cucumis sativus L.). The varied karyotypes between F₁ and mutant populations with short-arm (p) and long-arm (q) size indicate significant differences in the number of genes. The variation in chromosome arm length phenotypically causes changes in the morphological characters. Therefore, it is necessary to enhance the colchicine concentration and immersion time to obtain polyploidy.