High Trichome Density Research Articles

Impact of Cassava Cultivars on Stylet Penetration Behavior and Settling of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae).

This study investigates the settling preferences and feeding behavior of the Bemisia tabaci whitefly on six cassava cultivars using electrical penetration graph techniques. Six distinct electrical penetration graph waveforms-non-probing, stylet pathway, phloem salivation, phloem ingestion, intracellular puncture, and xylem feeding-were identified and analyzed. Significant differences in the frequency and duration of these waveforms were observed among the cassava cultivars. The whiteflies spent the majority of their time in the non-probing phase, particularly on the Huaybong 80, Kasetsart 50, Rayong 9, and Rayong 72 cultivars. CMR-89 cultivar exhibited higher total probe durations in the phloem salivation and ingestion waveforms, suggesting a greater potential for transmission of the Sri Lankan cassava mosaic virus. The study also examined trichome density and size across the cassava cultivars, revealing that CMR-89 had the highest density and small trichomes, while Huaybong 80 had the lowest density. Trichome characteristics significantly impacted whitefly behavior: larger trichomes were negatively correlated with whitefly settling, whereas higher trichome density was positively correlated with longer settling durations. These findings indicate that trichome-based resistance mechanisms are crucial in whitefly deterrence. Overall, the results suggest that cultivars with lower trichome density and larger trichomes are more resistant to whitefly infestation and subsequent Sri Lankan cassava mosaic virus transmission. These insights are valuable for cassava breeding programs focused on enhancing pest resistance, highlighting the importance of trichome characteristics in developing more resilient cassava varieties.

Characterization and screening of cotton (Gossypium hirsutum L.) germplasm for leafhopper (Amrasca biguttula biguttula (Ishida)) resistance

BackgroundCotton (Gossypium hirsutum L.) is one of the most significant fibre and cash crops and plays an important role in Indian industrial and agricultural economies. However, over the years quantity and quality have been hampered by the pest leafhopper. Leafhopper alone has been shown to cause yield losses of up to 40%. In this study, screening and evaluation were performed to identify and categorize 100 cotton genotypes along with 5 checks as resistant, moderately resistant, sensitive and highly sensitive to leafhoppers.ResultsA total of hundred genotypes were evaluated along with five checks for leafhopper resistance. Based on the screening results, a total of 19 genotypes were resistant to leafhoppers, which was on par with the findings of the check KC 3. The contents of total soluble sugar, total soluble protein, and total free amino acids were significantly positively correlated with the mean grade, whereas total phenols content and trichome density were significantly negatively correlated with the susceptibility grade. However, based on screening and biochemical analysis, the genotypes KC 2, JR-23, Samaru-26-T, D 4, TCH 1728, RS 253, and B-61-1862 exhibited high resistance to leafhopper.ConclusionAccording to the findings of this study, choosing genotypes with high total phenolics content together with high trichome density and low contents of total soluble sugar, total soluble protein, and free amino acids may aid in the development of resistant genotypes.

Evaluation of cotton varieties resistant to Amrasca biguttula (Hemiptera: Ciccadelidae) in the Indonesian agroecosystem to mitigate climate change impacts

Climate change employs substantial effects on agroecosystems, particularly the dynamics between plants and herbivores. In response, the adoption of pest-resistant varieties has emerged as a critical strategy within agroecosystems, notably in Indonesia’s cotton Integrated Pest Management (IPM). This research focused on evaluating the response of five cotton lines, which adapted to the Indonesian agroecosystem, to the cotton leafhopper (Amrasca biguttula) as a mitigating measure to climate change. Two upland cotton varieties, Tamcot SP 37 (susceptible) and LRA 5166 (resistant), served as standards for susceptibility and resistance to leafhoppers. The study examined leaf morphological characters, specifically trichome density, known to act as oviposition deterrents for leafhopper females, indicative of non-preference resistance. Low damage scores and high leaf trichome density comparable to the resistant variety (LRA 5166) were indicators of notable field resistance in lines 06062/3/3 and 06062/3/4 against A. biguttula during observations that spanned 35 to 105 days post-planting. These findings highlight the potential of these lines as promising cotton varieties, marked by their resilience to A. biguttula, fostering sustainable cultivation practices that address climate change impacts. This study underscores the intricate dynamics between plant-insect interactions and resilience strategies within agroecosystems.

Investigating biological performance, oviposition and diet preference of the twospotted spider mite feeding on various melon genotypes

The twospotted spider mite, Tetranychus urticae Koch, is one of the most dangerous pests for many crops worldwide, including the melon. Here, we raise the hypothesis that the resistance of melon genotypes to the spider mite is associated with the morphological characteristics of the leaves. We determined (i) the feeding preference and oviposition suitability of T. urticae on four melon genotypes, (ii) various biological parameters and population growth rate (ri) of T. urticae on different melon genotypes, (iii) the leaf morphology of the melon genotypes, and (iv) the relationship between the leaf characteristics and resistance to T. urticae. In no choice tests, lower numbers of adults and eggs of T. urticae were found in the genotypes CNPH 06–1047-343, CNPH 11–1071-43, and CNPH 06-1047-341 compared to control (Goldex). Individuals that fed on CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 genotypes had a longer egg incubation time, longer development time, lower immature viability, longer time to reach adult stage (egg–adult) and lower instantaneous rate of increase compared to control. These findings are in line with the fact that these three genotypes had thicker epidermis and greater mesophyll thickness than control genotype “Goldex”. Even the genotypes CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 had higher trichome densities, this morphological characteristic was not related with the resistance to T. urticae. CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 showed antibiosis and antixenosis against T. urticae and that resistance of the melon to T. urticae wss associated with the greater thickness of the leaf epidermis and mesophyll.

Chemical and structural heterogeneity of olive leaves and their trichomes

Many biological surfaces have hairs, known as trichomes in plants. Here, the wettability and macro- and micro-scale features of olive leaves are analyzed. The upper leaf side has few trichomes, while the lower side has a high trichome density. By combining different techniques including electron and atomic force microscopy, trichome surfaces are found to be chemically (hydrophilic-hydrophobic) heterogeneous at the nano-scale. Both olive leaf surfaces are wettable by water, having a high water contact angle hysteresis and great drop adhesion. The ultra-structural pattern observed for epidermal pavement cells differs from the reticulate cuticle structure of trichomes which shows that leaf surface areas may be substantially different despite being located nearby. Our study provides evidence for the nano-scale chemical heterogeneity of a trichome which may influence the functional properties of biological surfaces, such as water and solute permeability or water capture as discussed here for plants.

Identification of quantitative trait loci (QTLs) regulating leaf SPAD value and trichome density in mungbean (Vigna radiata L.) using genotyping-by-sequencing (GBS) approach.

Quantitative trait loci (QTL) mapping is used for the precise localization of genomic regions regulating various traits in plants. Two major QTLs regulating Soil Plant Analysis Development (SPAD) value (qSPAD-7-1) and trichome density (qTric-7-2) in mungbean were identified using recombinant inbred line (RIL) populations (PMR-1×Pusa Baisakhi) on chromosome 7. Functional analysis of QTL region identified 35 candidate genes for SPAD value (16 No) and trichome (19 No) traits. The candidate genes regulating trichome density on the dorsal leaf surface of the mungbean include VRADI07G24840, VRADI07G17780, and VRADI07G15650, which encodes for ZFP6, TFs bHLH DNA-binding superfamily protein, and MYB102, respectively. Also, candidate genes having vital roles in chlorophyll biosynthesis are VRADIO7G29860, VRADIO7G29450, and VRADIO7G28520, which encodes for s-adenosyl-L-methionine, FTSHI1 protein, and CRS2-associated factor, respectively. The findings unfolded the opportunity for the development of customized genotypes having high SPAD value and high trichome density having a possible role in yield and mungbean yellow vein mosaic India virus (MYMIV) resistance in mungbean.

Variability assessment of Bambara groundnut (Vigna subterranea (L) Verdc) landraces based on the qualitative trait seed coat colour

In many parts of Sub-Saharan Africa, female subsistence farmers rely on the production of underutilized crops such as Bambara groundnut (Vigna subterranea (L.) Verdc) for both sustenance and generating income. Bambara groundnut is, however, grown at a low rate especially in South Africa. Although it has the potential to yield high amounts of seed and can grow under adverse weather conditions, amongst offering other benefits, it remains underutilized and under-researched. To date there are no improved varieties. Farmers therefore rely on indigenous knowledge systems to select varieties based on their preferences, thereby unconsciously contributing to genetic erosion of the crop. Improved varieties are important for adaptability under environmental stochasticity. This study was conducted to determine whether seed coat colour can be used as a basis for selecting Bambara groundnut landraces with favourable agronomic traits for breeding programs and development of genetically enhanced varieties. A completely randomized design with ten replications was used to assess whether landraces classified based on seed coat colour are both morphologically and genetically similar. Significant differences (P<0.05) in the yield parameters, number of pods per plant, and growth habit were observed. This suggests that some genotypes yield more seed than others. Anatomical assessment of the leaf revealed that there are genotypes with high trichome density and two types of trichomes on the same plant. These characteristics make those plants more resilient to disease pressure than others. There is, however, little evidence that these findings are related to the seed coat colour. Attributing one character i.e. seed coat colour to genetic diversity is therefore reductive and should not be undertaken.

Defence-related components in cucumber susceptibility to target spot

Target spot is an important disease in cucumber culture. Due to differences in the susceptibility of cucumber cultivars to the disease, the objective was to evaluate the behavior of three cvs. in terms of leaf trichome density and biochemical variables in the interaction with the pathogen Corynespora cassiicola. The density of trichomes was evaluated on both sides of the leaves. The activity of peroxidase and polyphenol oxidase enzymes and the levels of free and bound phenolic compounds were evaluated one, three and five days after inoculation or not with the pathogen. The enzymatic activity was higher in the Safira cv., less susceptible to the disease, in relation to the Taiko and Soldier cvs. Inoculated plants showed higher peroxidase activity, showing that the response to infection was accompanied by the synthesis of this enzyme, and it increased with the days after inoculation. The levels of phenolic compounds varied according to the cvs. and as a function of time, with the highest levels in the Safira and Soldier cvs. Higher density of trichomes was found in the Safira cv., with no differences between Soldier and Taiko cvs. The adaxial side of the leaves had a greater number of trichomes than the abaxial side. No direct relationships were observed between biochemical and trichome variables and disease severity in cucumber cvs., since the Soldier cv., the most susceptible to the disease, did not differ in relation to 'Taiko' in enzymatic activities, free phenolic compounds and number of trichomes, including higher levels of bound phenolic compounds.

Comparative genomics of flowering behavior in Cannabis sativa.

Cannabis sativa L. is a phenotypically diverse and multi-use plant used in the production of fiber, seed, oils, and a class of specialized metabolites known as phytocannabinoids. The last decade has seen a rapid increase in the licit cultivation and processing of C. sativa for medical end-use. Medical morphotypes produce highly branched compact inflorescences which support a high density of glandular trichomes, specialized epidermal hair-like structures that are the site of phytocannabinoid biosynthesis and accumulation. While there is a focus on the regulation of phytocannabinoid pathways, the genetic determinants that govern flowering time and inflorescence structure in C. sativa are less well-defined but equally important. Understanding the molecular mechanisms that underly flowering behavior is key to maximizing phytocannabinoid production. The genetic basis of flowering regulation in C. sativa has been examined using genome-wide association studies, quantitative trait loci mapping and selection analysis, although the lack of a consistent reference genome has confounded attempts to directly compare candidate loci. Here we review the existing knowledge of flowering time control in C. sativa, and, using a common reference genome, we generate an integrated map. The co-location of known and putative flowering time loci within this resource will be essential to improve the understanding of C. sativa phenology.

Studies on Morphophysiological and Biochemical Parameters for Sucking Pest Tolerance in Organic Cotton

The demand for organic cotton is primarily driven by manufacturers and brands with a corporate focus on environmental and social responsibility. These entities strive to be responsible stewards by seeking organic cotton, which not only offers environmental benefits but also provides softer, more durable, and longer-lasting clothing. Unlike conventional cotton, organic cotton is processed without the use of harsh chemicals, making it more comfortable for individuals with sensitive skin. A study was conducted at the Center of Organic Agriculture Research and Training Center, Department of Agronomy, Dr. PDKV, Akola, Maharashtra, India to evaluate 22 cotton genotypes, including control samples, using a randomized block design with three replications during the kharif (June–October) season in the years 2019–2020 and 2020–2021, under complete organic conditions. During the initial year of the study (2019–2020), visual observations were made to assess the incidence of sucking pests on the cotton genotypes’ leaves, including the top, middle, and bottom portions. The observations indicated promising results, leading to a more detailed study in the subsequent year (2020–2021). This extended study identified several tolerant genotypes to sucking pests, such as AV-G11, PA-255, GA-8004, AV-C14, and AV-G13 from the arboreum species, as well as AKH-09-5, a hirsutum cultivar. Among the recorded data, it was found that the lowest mean aphid population occurred at 90 days after sowing (DAS), with only 1.53 aphids per leaf. Similarly, the lowest mean populations of Cicadellidae, thrips, and whitefly were recorded at 0.75, 0.97, and 0.63 per leaf, respectively, all at 30 DAS. Microscopic analysis of trichome density and gossypol glands revealed a negative and significant correlation with Aphis gossypi (aphids), Cicadellidae sp. (Cicadellidae), and Thrips tabaci (thrips). However, a positive and significant correlation was found with Bemesia tabaci (whitefly). Furthermore, the estimation of total soluble sugar using the Anthrone method, total nitrogen, and crude protein showed positive and significant correlations with aphids, Cicadellidae, and thrips, but negative, significant correlations with whitefly. The findings indicate that higher trichome density provides greater resistance to sucking pest infestation. It was concluded that G. arboreum genotypes exhibit greater tolerance to sucking pests compared to G. hirsutum varieties. This implies that G. arboreum varieties may require less intensive pest management, aligning with organic farming principles. The discovery of these genotypes opens up possibilities for utilizing them as sustainable and pest-resistant options in cotton cultivation, promoting environmentally friendly and organic farming practices in cotton fiber production.

Assessing common bean genotypes for resistance to Diabrotica speciosa (Coleoptera: Chrysomelidae).

Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae) is a major pest of common bean (Phaseolus vulgaris L.; Fabales: Fabaceae), and adults can defoliate plants during the whole crop cycle. This study was conducted to evaluate the resistance to D. speciosa in 16 common bean genotypes (14 landraces and 2 cultivars), through three different experiments. In the laboratory, choice and no-choice feeding tests were performed to evaluate the percentage of leaf consumption. In the greenhouse, plant height, numbers of leaves, percentage of injured leaves, percentage of injury per leaf, weight of seeds, and D. speciosa survival were evaluated. Furthermore, trichome density, levels of peroxidase (POD), superoxide dismutase (SOD), and protein content in common bean leaves were assessed. In the laboratory, the genotypes Chumbinho Branco, Dobalde, Manteigado, IPR Tuiuiú, and 90D Mouro were the least consumed by D. speciosa. In the greenhouse, the genotypes Dobalde, Manteigado, and IPR Tuiuiú expressed tolerance to the pest, which was associated with a higher plant height and/or unchanged POD and SOD levels and protein content following insect feeding, and no reduction in seed production. The landrace 90D Mouro exhibited antixenosis and tolerance to D. speciosa, observed as a lower leaf injury, higher trichome density, lower protein contents, higher SOD level and no reduction in seed weight. Overall, we have shown that antixenosis and tolerance can help overcome damages resulting from D. speciosa feeding, with emphasis on four common bean genotypes that may be useful in plant breeding programs aimed at controlling D. speciosa in common bean crops.

Prey consumption capacity and functional response of Phytoseiulus persimilis (Acari: Phytoseiidae) feeding on Tetranychus urticae (Acari: Tetranychidae) on different cotton varieties

This study aimed to determine the predatory performance of Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) against Tetranychus urticae Koch (Acari: Tetranychidae) on six different cotton varieties (Gloria, Lima, Carla, DP-396, Edessa, ST-468) with different leaf characteristics. The eggs and the protonymph stages of the prey with six prey densities (5, 10, 20, 40, 80 and 160) were separately offered to a single female predator to determine its predation and oviposition rates for 24h. The results showed that P. persimilis exhibited a Type II functional response to both egg and protonymphal stages of T. urticae irrespective of cotton varieties. The highest attack rates (α) were 0.045 h&lt;sup&gt;- &lt;/sup&gt;and 0.085 h&lt;sup&gt;-&lt;/sup&gt; when the predator fed on eggs and protonymphs of T. urticae on Gloria (low trichome density) variety, respectively. There was a great similarity between the handling times (Th) of P. persimilis feeding on T. urticae eggs and protonymphs among different cotton varieties. No significant difference was found in terms of food consumption of P. persimilis fed on T. urticae eggs in different cotton varieties. In contrast, food consumptions of P. persimilis in all protonymph densities (except 160) were significantly higher on varieties with lower trichome density (Gloria and Lima) compared to the varieties with higher trichome density (Edessa and ST-468). The current study showed that the leaf trichome density of the cotton plant affected the prey consumption capacity of P. persimilis on T. urticae protonymphs. However, more studies are needed to address the issue from a wider perspective, especially to observe the performance and biological control potential of P. persimilis on cotton varieties under field conditions.

Characterization of leaf surface phenotypes based on light interaction

BackgroundLeaf surface phenotypes can indicate plant health and relate to a plant’s adaptations to environmental stresses. Identifying these phenotypes using non-invasive techniques can assist in high-throughput phenotyping and can improve decision making in plant breeding. Identification of these surface phenotypes can also assist in stress identification. Incorporating surface phenotypes into leaf optical modelling can lead to improved biochemical parameter retrieval and species identification.ResultsIn this paper, leaf surface phenotypes are characterized for 349 leaf samples based on polarized light reflectance measured at Brewster’s Angle, and microscopic observation. Four main leaf surface phenotypes (glossy wax, glaucous wax, high trichome density, and glabrous) were identified for the leaf samples. The microscopic and visual observations of the phenotypes were used as ground truth for comparison with the spectral classification. In addition to surface classification, the microscope images were used to assess cell size, shape, and cell cap aspect ratios; these surface attributes were not found to correlate significantly with spectral measurements obtained in this study. Using a quadratic discriminant analysis function, a series of 10,000 classifications were run with the data randomly split between training and testing datasets, with 150 and 199 samples, respectively. The average correct classification rate was 72.9% with a worst-case classification of 60.3%.ConclusionsLeaf surface phenotypes were successfully correlated with spectral measurements that can be obtained remotely. Remote identification of these surface phenotypes will improve leaf optical modelling and biochemical parameter estimations. Phenotyping of leaf surfaces can inform plant breeding decisions and assist with plant health monitoring.

Orthophosphate fluxes in scattered trees from fragmented Andean landscapes highlight a biogeochemical role of foliar traits in pioneer species

AbstractHighly diverse neotropical ecosystems exhibit a natural limitation of phosphorus in the soil, sufficient to limit productivity and structure. This is more pronounced in Andean ecosystems, with high forest fragmentation and forest loss rates aggravating the effect. Previous studies have highlighted the importance of precipitation and its interaction with the canopy on nutrient inputs into forests. However, few studies have quantified the potential effects of structural and morphological tree diversity on the dynamics of phosphorous inputs on these ecosystems. In this study, we determined the association between 12 morphological plant functional traits and the movement of water‐driven orthophosphate from the canopy into the soil in 20 individuals of five tree species, on single individuals scattered across a human‐disturbed montane landscape in the Colombian Andes: Croton magdalenensis, Andesanthus lepidotus, Vismia baccifera and Quercus humboldtii and a commonly planted exotic species Eucalyptus globulus. We quantified PO4‐P concentrations in precipitation, throughfall and stemflow in all trees for 14 isolated rainfall events. In general, our results show a general enrichment of PO4‐P concentration in the net precipitation after passing through tree canopies. One particular species, C. magdalenensis, an ecological pioneer, had notably higher values of PO4‐P concentration. This condition relates, potentially, to a particularly higher epiphyte load, high leaf area and high trichome density. This condition potentially facilitates biogeochemical exchange and improves ecological functions associated with early stages of forest recovery (where pioneer species dominate forest composition). Our results are particularly relevant given that the highest contributions of PO4‐P to the soil occur in native species, which become key structures in the recovery of fragmented Andean ecosystems.

TEMPRANILLO homologs in apple regulate flowering time in the woodland strawberry Fragaria vesca

The long juvenile period of fruit trees makes their breeding costly and time-consuming. Therefore, flowering time engineering and shortening the juvenile phase have become a breeding priority for the genetic improvement of fruit tree crops. Many economically valuable fruit trees belong to the Rosaceae family including apples and strawberries. TEMPRANILLO (TEM) acts as a key player in flowering time control through inhibiting FT function. Two genes with high sequence similarity with the Arabidopsis TEM genes were isolated from apple (Malus domestica). Due to the complexity of carrying out functional studies in apple, we characterized their function in woodland strawberry as well as their expression in apple. The expression of MdTEM genes in apple tissues from juvenile plants was dramatically higher than that in the tissues from adult trees. In woodland strawberry, the overexpression of MdTEM genes down-regulated FvFT1, FvGA3OX1, and FvGA3OX2 genes in strawberry. The MdTEM-overexpressing lines exhibited delayed flowering, in terms of days to flowering and the number of leaves at flowering. While, RNAi-mediated silencing of TEM resulted in five days earlier flowering, with a lower number of leaves, a higher trichome density, and in some cases, caused in vitro flowering. According to these results and in silico analyses, it can be concluded that MdTEM1 and MdTEM2 can be considered as orthologs of FvTEM and probably AtTEM genes, which play an important role in regulating the juvenile phase and flowering time through regulating FT and GA biosynthetic pathway.

Evaluation of maize germplasm for physio-morphological traits against fall armyworm

The fall armyworm (FAW), scientific name Spodoptera frugiperda (J.E. Smith), poses a significant challenge to farmers and agricultural systems due to its ability to adapt, reproduce rapidly, and develop resistance to pesticides. Hence, it is essential to adopt effective and feasible approaches to managing FAW. The present research aimed at identifying the physio-morphological traits in 22 diverse maize genotypes that influence resistance to FAW. Among the tested ones, moderately resistant genotypes had the highest trichome density (CML 71, CML 67, and CML 335), minimum leaf area, and leaf width (DMRE 63, CML 71, and CML 67). Moderately resistant genotypes, viz., CML 67 (0.14 mm), CML 71 (0.14 mm), CML 561 (0.14 mm), and DMRE 63 (0.14 mm), exhibited significantly higher leaf toughness. Furthermore, the lowest relative water content was recorded in moderately resistant genotypes (DMRE 63, CML 71, and CML 67). The maximum cob length was observed in the moderately resistant genotype, CML 71 (18.56 cm), followed by CML 67 (18.26 cm), which was on par. Among moderately resistant genotypes, CML 71 had the greatest cob width of 4.97 cm, followed by CML 67 (4.88 cm), CML 561 (4.66 cm), CML 335 (4.66 cm), and DMRE 63 (4.62 cm), and these were statistically comparable. Of the genotypes evaluated, the moderately resistant genotypes CML 71, CML 67, and DMRE 63 registered significantly higher yields of 135.04 g/plant, 120.65 g/plant, and 117.92 g/plant, respectively. This information on physio-morphological traits is helpful in breeding programs focusing on maize resistance to FAW.

Paclobutrazol Improves The Agronomic Performance and Micromorphological Profile of Five Local Black Rice ( Oryza sativa L.) Varieties in Central Java Indonesia

Local black rice (Oryza sativa L.) is one of the biodiversity of rice in Indonesia, which has tall stature and long cultivation period, easy to lodge, and requires more intensive care. Paclobutrazol (PBZ) is a plant growth inhibitor compound that could reduce plant height and accelerate plants entering the generative phase. This study aimed to determine the effects of PBZ concentration on the agronomic character and micromorphological profile of five local black rice varieties. This research was conducted experimentally using a completely randomized factorial design. The first factor was the local black rice variety (Brebes, Klaten, Magelang, Pati, and Pekalongan ), while the second was PBZ concentration (0, 100, 200, and 300 ppm) with three replications. PBZ spraying was conducted in the fourth week after planting. The data obtained were analyzed using ANOVA and HSD test (α=5%). The results showed that the concentrations of PBZ 300 ppm produced the heaviest 100 grains. The Klaten variety had wide abaxial stomata, the Magelang variety had high abaxial stomata density, while the Pati variety had long abaxial stomata and heaviest 100 grains. The interaction between Brebes variety and PBZ 0 ppm produced high adaxial stomatal density, Klaten variety, and PBZ 100 ppm have vast adaxial stomatal and high abaxial trichome density. Pati variety and PBZ 0 ppm had the most tillers, while Pati variety and PBZ 100 ppm had long adaxial stomata and the most grains per panicle. The study's critical findings are that PBZ gives different micromorphology improvements and increases agronomic performance in local black rice.

Alteration in Light Spectra Causes Opposite Responses in Volatile Phenylpropanoids and Terpenoids Compared with Phenolic Acids in Sweet Basil (Ocimum basilicum) Leaves.

Basil (Ocimum basilicum, cv. Dolly) grew under three different light spectra (A, B, and C) created by light-emitting diode lamps. The proportions of UV-A, blue, and green-yellow wavelengths decreased linearly from A to C, and the proportions of red and far-red wavelengths increased from A to C. Photosynthetic photon flux density was 300 μmol m–2 s–1 in all spectra. The spectrum C plants had highest concentrations of phenolic acids (main compounds: rosmarinic acid and cichoric acid), lowest concentrations and emissions of phenylpropanoid eugenol and terpenoids (main compounds: linalool and 1,8-cineole), highest dry weight, and lowest water content. Conversely, spectra A and B caused higher terpenoid and eugenol concentrations and emissions and lower concentrations of phenolic acids. High density of peltate glandular trichomes explained high terpenoid and eugenol concentrations and emissions. Basil growth and secondary compounds affecting aroma and taste can be modified by altering light spectra; however, increasing terpenoids and phenylpropanoids decreases phenolic acids and growth and vice versa.

Morphological and biochemical resistance to Helicoverpa armigera (Lepidoptera: Noctuidae) in tomato

Tomato (Solanum lycopersicum L.) production in the tropics suffers from depredation by the tomato fruit borer, Helicoverpa armigera (Hübner), causing severe economic losses. Development of H. armigera resistant tomato cultivars in India is very limited due to lack of good sources of resistance for breeding. Use of insect resistant cultivars could reduce indiscriminate use of insecticides. A total of twenty-two tomato genotypes were assessed under field conditions for resistance to H. armigera during 2017–18 and 2018–19. Morphological and biochemical factors associated with the expression of resistance to this pest in tomato were estimated and considered as potential markers of resistance. The six genotypes, Kashi Sharad, Pb Barkha-1, DVRT-1, Pb Barkha-2, DVRT-2 and Pusa Rohit, were least infested by H. armigera with fruit weight loss ranging from 4.63 to 8.71 percent and were classified as resistant. Expression of resistance was associated with higher trichome density on leaves and calyxes, higher fruit pericarp thickness, higher phenol content in leaves and fruits, and lower soluble sugar and protein contents in leaves and fruits. Resistant genotypes of tomato with these factors may be used as sources of resistance in future breeding programs to enhance resistance to H. armigera in commercially cultivated tomato varieties.

Resistance of True Citrus species to Diaphorina citri

Host genetic resistance is a promising strategy for the management of Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and consequently Huanglongbing (HLB). To date, no study has investigated the resistance to D. citri in the clonal and vegetatively propagated plants of the Microcitrus, Eremocitrus, and Atalantia genera. This study assesses Near and True Citrus genotype antixenosis and antibiosis against D. citri, with trichome density and volatile emission as possible mechanisms of resistance. All genotypes were oviposited by D. citri, however, 8 of 14 genotypes were less oviposited than Citrus × sinensis 'Valencia' (susceptible control). Diaphorina citri nymphs had lower nymphal viability in E. glauca (31%) and M. warburgiana (58%) than that in Citrus × sinensis (77%). The behavioral assay showed that 30% of D. citri nymphs in the last instars evaded E. glauca shoots, whereas no nymphs evaded Citrus × sinensis shoots. A higher trichome density was observed in E. glauca shoots compared to the other genotypes. Chemical analysis revealed differences in the volatile profiles of E. glauca and Citrus × sinensis. Eremocitrus glauca and M. warburgiana genotypes were more resistant to D. citri than Citrus × sinensis. Higher trichome density in the shoots may negatively influence the development of D. citri nymphs. Eremocitrus glauca volatiles may also be involved in their resistance to D. citri. © 2022 Society of Chemical Industry.