Petiole Cross Section Research Articles

IDENTIFIKASI KERAGAMAN FENOTIP KARAKTER KUALITATIF DAN KUANTITATIF KELAPA SAWIT (Elaeis guineensis Jacq.) ASAL ANGOLA

The research entitled identification the phenotypic variance of qualitative and quantitative characters of oil palm (Elaeis guineensis Jacq.) origin of Angola. The objective of the study was to determine the specific characteristics of the oil palm population of dura and tenera Angolan germplasm on phenotypical characterization whether qualitatively and quantitatively as well. The research was conducted in seeds garden of the oil palm seeds company in Siak Hulu of Kampar District. The genetic material used in this study was oil palm germplasm as much as 1996 oil palms in 15.50 hectars. The Angola accession population consisted of 80 Dura accessions with 1,309 oil palms and 26 Tenera Accessions with 687 oil palms. The analytical method used is the Coefficient of Phenotypic Variation (KKF) and Principal Component Analysis (PCA). The results show that the main component of the quantitative variable can explain the variation of the Angolan oil palm population by 79.76% with parameters such as oil to bunch (%), oil to fruit (%), dry mesocarpto fruit (%), relative leaf area (m²), wet mesocarp to fruit, frond length, palm height, number of leaves, periole width (cm), and petiole cross-section (cm²). The proportion of low KKF with a high O/B average is found in AGO001, AGO086, AGO101, and AGO 106.

ANATOMY OF THE ENDEMIC ALYSSUM PATERI SUBSP. PATERI

Objective: Alyssum pateri Nyár. subsp. pateri is an endemic plant known as "kanatlı kevke" in Türkiye. The plant is perennial and in semi-shrub form. The plant is traditionally used externally in the treatment of rheumatism in Bingöl (Türkiye). Microscopic analysis of the anatomical structures of plants can provide useful information for taxonomic classification. Light microscopy analysis is a widely used and effective method for the identification of medicinal plants. In this study, the anatomical features of the A. pateri subsp. pateri were examined. Material and Method: The plant material was collected from Ankara (Türkiye). The samples were protected in 70% alcohol. The cross and surface sections were cut by hand with a razor blade into microscopic preparation form. A Leica DM 4000B microscope was used for anatomical analysis and micro photographs. Result and Discussion: The anatomical characters of the leaf, petiole and stem of the Alyssum pateri subsp. pateri were revealed. The leaf is dorsiventral and contains 1-2 rows of palisade parenchyma. Cruciferous stomata and stellate hairs are located on the lower epidermis. The petiole cross-section is sulcate and stellate hairs are observed in the epidermal layer. The main vein is arc-shaped and is accompanied by lateral veins. The stem is disc-shaped. Stem epidermis contains stellate hairs. The interfascicular tissue between the xylem strands of the vascular bundles is composed lignified cells. Vascular bundles are surrounded by a pericyclic sclerenchymatous cap.

ANATOMICAL STRUCTURE OF THE CONDUCTING SYSTEM OF THE <i>POPULUS TREMULA</i> (SALICACEAE) LEAF

A study of the conductive elements arrangement throughout the petiole length and in the midrib of the Populus tremula leaves was carried out. The plants growing wild in Perm and artificially planted in residential areas were studied. It was found that the shape of the petiole cross-section varies throughout its length from broadly heart-shaped (at the distal end) to strongly flattened laterally (at the leaf blade). In the middle part, the petiole is almost rounded. Three groups of collateral conducting bundles enter the petiole, where they regroup to be arranged at 4–5 levels. The additional basal veins of the leaf blade include lateral parts of the groups of bundles of the levels I, II and III. At a distance of about 1 cm from the base of the leaf blade, the leaves of brachyblast have conducting bundles arranged following a linear type. The division of groups of conducting bundles is carried out symmetrically or asymmetrically. The leaves with an asymmetric leaf blade can have both symmetrical and asymmetrical arrangement of conductive elements. There were no significant differences in the anatomical structure of P. tremula petioles between the plants growing in culture and in wild. Stress conditions of the urban environment do not have a fundamental effect on the location of conductive tissues in the petiole throughout its length.

Performance of three oil palm varieties on the East Coast of North Sumatra

The planting material, environmental conditions, and agricultural practices determine the oil palm performance. This research aimed to observe the performance of three oil palm varieties produced by IOPRI in Adolina Estate, Serdang Bedagai, North Sumatra. Adolina Estate is located on the eastern part and has a distinctive equatorial rainfall type with a sandy clay loam soil texture. The DyP Dumpy, DxP PPKS 540, and DxP Langkat varieties have been planted since 2010 in the same block with similar soil conditions and agricultural practices with total samples of 101, 147, and 124 trees, respectively. The growth parameters were height, length of rachis, petiole cross-section (PCS), and leaf area (LA), while the production parameters observed included the average bunch number, bunch weight, and yield. The results showed that DyP Dumpy had the slowest height growth with the most extended rachis length. DxP PPKS 540 has the highest average of PCS and LA, while the DxP Langkat had the fastest height growth and shortest rachis length. Furthermore, the DxP PPKS 540 variety produced the highest average yield, 24.85 tons ha−1, while DyP Dumpy and DxP Langkat have 23.19 tons ha−1 and 23.95 tons ha−1, respectively.

USE OF BITUMEN-TREATED FABRIC MULCH DURING FIRST YEAR REPLANTING OF IMMATURE OIL PALMS

The use of empty fruit bunch (EFB) mulching in oil palm replants has for decades been implemented as best practice across the industry. In this study, several trials were initiated to evaluate the effectiveness of bitumen-treated fabric mulch (BFM) as an alternative for EFB mulching on oil palm growth performance in replants. The trial was conducted in Jeleta Bumi Estate, Sabah for 12 months. The treatments evaluated were mulching using BFM with a total quantity of first-year fertiliser applied underneath (T1) and normal EFB mulching with the standard bi-monthly manuring programme (T2). The treatments were arranged using randomised complete block design (RCBD) with four replications. The palms’ rachis length, petiole cross-section, and total fronds were measured 12 months after planting to calculate the relative leaf area (RLA), true leaf area (TLA), and leaf area index (LAI). Leaves from frond number nine were sampled for nutrient analysis. Concurrently, these treatments were replicated at a semi-commercial scale in five estates totalling 466.36 hectares under T1. Generally, there was no significant difference (P>0.05) in all parameters measured for both vegetative performance and leaf nutrients between T1 and T2. Additionally, box plot analysis indicated a uniform growth pattern across treatments from the calculated RLA, TLA, and LAI. Cost-benefit analysis indicated a saving of up to 62 per cent at 12 months after planting. This includes costs of EFB transportation, weeding and manuring rounds. Concomitantly, labour dependency could be further reduced, particularly of interest under current industry labour shortages. Response by users highlighted in reduced road maintenance, minimised rhinoceros beetle damage and lower frond scorching.

ANATOMICAL VARIATIONS OF LEAVES PETIOLES IN SOME TAXA OF THE GENUS TRIFOLIUM L. (FABACEAE) IN IRAQ.

This study was conducted on the 22 taxa of the genus Trifolium L. which grow naturally as wild plants in all geographical districts in Iraq. A comparative study of the leaf petioles was anatomically examined by paraffin method. Petiole cross-section outline shapes have divided the genus species into fourteen groups and sub-groups. According to the microscopical characteristics the cortex of petioles showed to contain layers of various tissues, the collenchyma tissue observed sub-epidermally in some species, and cortexes of the others were devoid of collenchyma. The sclerenchyma strands were noted in three patterns; above vascular bundles, above and beneath vascular bundles, and the sclerenchyma strands completely surrounded the vascular bundles in some species. Petiole cross-sections have been divided into three categories as; three vascular bundles and absent of accessory vascular bundles, three vascular bundles with one of accessory vascular bundle, three vascular bundles with two accessory vascular bundles. The comparative results confirmed that these characteristics collectively are of high taxonomic value and can contribute to separating the studied genus species, finally, based on these variations, the anatomical classification key was constructed to separate the genus taxa.

Taxonomic relevance of petiole anatomical and micro-morphological characteristics of Clematis L. (Ranunculaceae) taxa from South Korea.

We assessed the micro-morphological and anatomical structures of the petioles of 19 Clematis taxa from South Korea. The petiole surface features were observed with the help of stereomicroscopy and scanning electron microscopy, and the anatomical features are studied via microtomy and light microscopy. The results of this study showed that the presence/absence and abundance of trichomes, petiole cross-section outlines, upper surface wings and grooves, and the number of vascular bundles were useful for species discrimination in Clematis. Among the studied taxa, C. hexapetala was the only species with a glabrous petiole surface. Two types of trichomes were observed in the other 18 taxa: long, non-glandular and flagelliform trichomes and short, glandular capitate trichomes. We found four to six major vascular bundles and a maximum of eight interfascicular vascular bundles (C. heracleifolia and C. urticifolia) in the 19 taxa. A cluster analysis based on UPGMA identified six clusters with 18 nodes. Although the number of taxa investigated was limited, taxa from the sections Tubulosae, Viorna, and Astragene clustered with each other in the UPGMA phenogram due to the overall similarity of petiole features. Based on this observation, we can conclude that most of the petiole features are limited to the species level, and thus, the data obtained could be used as descriptive and/or diagnostic features for particular taxa, which may be useful for the investigation of problematic taxa in the genus.

Three-dimensional quantification of twisting in the Arabidopsis petiole

Organisms have a variety of three-dimensional (3D) structures that change over time. These changes include twisting, which is 3D deformation that cannot happen in two dimensions. Twisting is linked to important adaptive functions of organs, such as adjusting the orientation of leaves and flowers in plants to align with environmental stimuli (e.g. light, gravity). Despite its importance, the underlying mechanism for twisting remains to be determined, partly because there is no rigorous method for quantifying the twisting of plant organs. Conventional studies have relied on approximate measurements of the twisting angle in 2D, with arbitrary choices of observation angle. Here, we present the first rigorous quantification of the 3D twisting angles of Arabidopsis petioles based on light sheet microscopy. Mathematical separation of bending and twisting with strict definition of petiole cross-sections were implemented; differences in the spatial distribution of bending and twisting were detected via the quantification of angles along the petiole. Based on the measured values, we discuss that minute degrees of differential growth can result in pronounced twisting in petioles.

Morphological and anatomical study of the genus Sambucus L. (Adoxaceae) in Iran

Sambucus (Adoxaceae) is a tall tree-like shrub distributed throughout temperate and subtropical regions in Europe, Asia, North Africa and North America. Since there is not any morphological and anatomical comprehensive study on Sambucus species in Iran and Sambucus nigra is located in the Arasbaran region with very limited distribution, we have encouraged studying the patterns of morphological variation and anatomical structure among Sambucus taxa. In this study, the morphological and anatomical structure of 18 populations from two species of Sambucus (S. ebulus and S. nigra) has been considered to evaluate the relationships in this genus. In total, nine quantitative and nine qualitative morphological features were evaluated and measured. Ward’s dendrogram showed two main clusters. The first cluster is composed of a population of S. nigra. The second cluster was composed of two subsets and contained populations of S. ebulus in Golestan, Mazandaran and Gilan provinces. There were two types of epidermal cells, puzzle-shaped in S. ebulus and oblong cells in S. nigra. The stems are rounded shape in both species. The margin is quite wavy in S. ebulus and straight in S. nigra. Both species showed a rounded shape with a wavy margin in petiole cross-sections. Pedicel cross-sections of both species are similar to each other in the general shape of cross-sections and margins. Both are rounded in shape and the margin is quite sinuous shapes in S. ebulus and wavy in S. nigra. The present study showed that a combination of morphological and anatomical data provides reliable evidence for the differentiation of two species of S. nigra and S. ebulus.

QUANTITATIVE TRAIT LOCI (QTL) LINKED TO COMPACTNESS IN AN INTERSPECIFIC BACKCROSS TWO (BC2) POPULATION OF OIL PALM

Conventional quantitative trait loci (QTL) analysis of a mapping family is carried out to generate molecular tools for development of compact interspecific hybrid palms that can be planted more closely for higher yields per unit land area. Genetic maps were constructed for an interspecific backcross two (BC2) oil palm population using single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers. A total of 1744 markers were mapped onto 16 linkage groups, spanning 1499.5 cM with an average marker interval of 0.86 cM. Using empirical genome and chromosome-wide thresholds, QTL analysis yielded a number of significant associations with vegetative characters for palm compactness. Subsequent QTL analysis revealed two major and two putative QTL linked to rachis length and petiole cross-section, two important characters for palm compactness. The QTL identified are an important step towards the implementation of marker assisted selection (MAS), enabling breeders to make early informed decisions on improving interspecific hybrids.

Систематическое положение Populus ciliata Wall. ex Royle по результатам изучения морфологии побегов и петиолярной анатомии

Populus ciliate – ciliated poplar is distributed in the Himalayas at altitudes from 1300 to 3400 m above sea level, along river banks and wet slopes. The systematic position of the taxon remains unclear, although in most modern works it is attributed to the Tacamahaca section. The purpose of this study is to study the morphological features of crown shoots and the anatomical structure of petioles of Populus ciliata leaves to clarify its systematic position. Studies of the morphology of P. ciliata showed that it did not have specialized shortened shoots marking a section of balsamic poplars – diskoblasts. The most important signs of petiolar anatomy allowing the identification of poplar taxa at the section level are: the shape of the petiole cross section, the contours of its adaxial and abaxial sides, the shape of the rings of closed collateral bundles, the shape of the vascular system. A comparison of the obtained sections of P. ciliata with representatives of the Tacamahaca section indicates that the plants studied do not belong to balsamic poplars, since they differ in the absence of a groove pronounced on the adaxial side. The latter in the form of a small recess in the slice is fixed only at the place of its transition into the leaf blade. The contours of the abaxial and adaxial sides are round, the shape of the vascular system of the petiole is not highly arched like that of balsamic poplars, but linear, formed by elliptical rings of closed collateral bundles.

Anatomical, Histochemical and Cytogenetic Features of <i>Doryopteris triphylla</i> (Pteridaceae)

Doryopteris triphylla (Pteridaceae-Cheilanthoideae) grows in xeric habitats in Brazil, Paraguay, Uruguay and Argentina. The aim of this study was to characterize D. triphylla anatomically, histochemically and cytogenetically. For anatomical characterization, rhizomes, roots, petioles and leaves were made and then stained using Safranine-Astra Blue for further observations. Leaf blades were also cleared. For histochemical analysis, leaf cross sections were stained with different reagents to identify glandular trichomes compounds. For cytogenetic characterization, a karyogram was performed using laboratory cultivated roots. Results show a dictyostelic rhizome covered with scales with apical secreting gland; diarch roots; petiole cross-sections show thick cuticle, uniseriate epidermis, parenchymatic cortex cells with thick walls and a vascular bundle with two xylem groups; and hypostomatic fronds with glandular trichomes. Histochemical studies of secretion products of the glandular trichomes were positive for polysaccharides, pectins, lipids, acid lipids, dihydroxyphenols, phenols and flavonoids. Cytogenetically, D. triphylla is described as a diploid species (2n = 60), with chromosomes gradually decreasing in size. The apical glands in scales of rhizomes, the presence of two xylem groups in the vascular bundle in the petiole and the glandular trichomes on the abaxial surface are new contributions to the species. The type of chemical products secreted by glandular leaf trichomes and karyotype estimation is shown for the first time in this species.

مطالعه صفات تشریحی برگ و دمبرگ سرده Alchemilla از تیره گل سرخیان در ایران و کاربرد آنها در تاکسونومی عددی

The current study deals with leaf and petiole anatomical survey of 24 species of the genus Alchemilla from Iran. After collecting and identifying the specimens, leaf and petiole cross sections were prepared by hand and best sections were taken for staining and light microscope studies. In this survey, 43 anatomical traits were carefully examined. The result showed that glandular trichome, number and arrangement of adjacent epidermal cells and their wavy or smooth walls, presence and absence of the extraxylary fibers are the most outstanding anatomical evidences. In order to determine the species relationship, 39 quantitative characters were undertaken in principal component analysis (PCA). PCA analysis led to complete separation of some species including A. persica, A. caucasica, A. hessii, A. pseudocartalinica, A. rechingeri, A. melancholica, A. hyrcana, A. microscopica and A. erythropoda, formation of 3 main groups and two subgroups. Our findings revealed that leaf and petiole anatomical characters are limited taxonomic value. The numerical analysis of these traits has disability in revealing the species relationship.

Petiole and leaf traits of poplar in relation to parentage and biomass yield

Poplars grown under a short-rotation coppice (SRC) regime for biomass production offer a promising alternative source of renewable energy to fossil fuels. We examined the potential of leaf and petiole traits of 12 different poplar genotypes as early selection criteria for breeding and selection programmes. Petiole traits included theoretical hydraulic conductivity of the petiole, petiole xylem area and the number of vessels in each petiole. The different genotypes clustered largely according to their breeding programmes and to their parentage. Leaf and petiole traits showed strong correlations, which enabled the prediction of difficult-to-measure petiole traits as xylem area, total vessel lumen area and number of vessels based on the more common and easily measurable leaf dry mass. We found significant correlations between above-ground woody biomass and nine leaf and petiole traits. We developed three predictive correlative models based on the easy-to-measure petiole and leaf traits (petiole cross-section area, petiole thickness and leaf dry mass). These simple models can be used as early selection criteria for biomass yield in poplar breeding programmes. The usefulness of the easy-to-measure petiole thickness for biomass prediction should be further tested on other poplar genotypes.

The Analysis of Petiole Histological Traits Through an Evaluation of Water Deficit Tolerance of Sugar Beet Genotypes

Water stress is considered as one of the most widespread limitations to sugar beet productivity and yield stability. Since leaf is the most significantly affected organ by drought, we focused on the petiole histological features of ten sugar beet genotypes that previously showed divergent responses to lack of water in the field. The aim was to calculate volume densities of petiole different tissues and determine the histological sources of the genotypic differences in the breeding material with respect to water use efficiency. Comparative histological analysis of the petiole was performed using classic anatomical (proximal and distal segments) and stereological methods. The plants were grown in semi-controlled glasshouse conditions. The general structure of the sample variability was established by Principal component analysis, based on the correlation matrix data. This study suggests that determination of the variation in the histological characteristics of the petioles can play an important role in water management in plants. The results reveal a higher level of variability in morphometric parameters due to the fact that petiole cross-section shapes change with its maturity. Characteristics, such as (i) petiole shape, (ii) arrangement and number of vascular bundles, (iii) number and size of vessels, (iv) volume density and distribution of collenchyma, and (v) volume density of parenchyma are promising criteria that can help in the selection of more drought tolerant genotypes.

Comparative morphology, anatomy and palynological studies of perennial species of Onobrychis (Fabaceae) in northeast Iran

This study examined morphological, anatomical and palynological characters for six species, two subspecies and two varieties of perennial Onobrychis growing in northeast Iran. In the morphological study, shape, size and color of vegetative organs and legumes were assessed. For the anatomical study, cross sections of mature fresh or dried stems, leaflets and petioles were prepared and stained. In the palynological study, pollen were extracted, acetolysed and observed by SEM. The morphological study indicated that some characteristics varied among species, such as shape of stipules and calyx teeth, color and shape of corolla segments and legumes and an identification key is provided based on these characters. Also, in internal structure some differences were noticed in the shape of petiole cross sections, the thickness of cortex and pith shape in petioles and the arrangement of vessels in stems. Some anatomical characters proved useful to identify species, but not sections. Palynological results showed circular and obtuse triangular pollen in polar view and elliptical pollen in equatorial view with reticulate ornamentation. In addition, a cluster analysis was done based on morphological, anatomical and palynological features. The resulting dendrogram confirmed the taxonomic treatment suggested by Sirjaev and Rechinger.

Effectiveness of Urea-Coated Fertilizer on Young Immature Oil Palm Growth

Urea-coated fertilizers were invented to reduce ammonia volatilization and act as slow-release fertilizers in the oil palm field. This study was designed to examine the effectiveness of three types of urea-coated fertilizers namely Urease Inhibitor-coated urea 25% N (UICU), resin-coated urea 43% N (RCU), Sulphur-coated urea 32% N (SCU), uncoated urea 46% N (UU) and uncoated AS, (SOA) 21%N on oil palm early growth. The trial commenced from planting of the new oil palms until 36 months after planting (MAP). The fertilizer rates were applied with equivalent nutrient content of conventional compound fertilizer, NPKMg (9/9/12/4+0.5%B-AS based) as Control (Co) treatment. From the analysis, RCU showed significantly bigger girth size over UU and UAS by 13%, respectively starting at 18 MAP and 24 MAP while SCU recorded significant performance over UU by 8% at 36 MAP. The result also showed that SCU produced significantly longer fronds over Co, UU and UAS by 9%, 13% and 10%, respectively at 30 MAP. The similar performance was shown by SCU which produced bigger petiole cross section (PCS) and higher leaf dry weight over UU and Co at 30 to 36 MAP respectively. Foliar analysis found that higher leaf- N was recorded at the SCU plot and exceeded the UU by 18% and over the critical level by 7% at 24 MAP. From the results, it indicated that SCU had consistent performance over UU on girth size, frond length, PCS, leaf dry matter and leaf-N content. Even though there was no significant difference between the other types of urea coated fertilizers, SCU was able to produce more vigorous vegetative growth. Therefore, SCU fertilizer can be used as an alternative source of urea to improve immature oil palm growth especially in dry regions where high volatilization rate occurs. 

Variability and performance evaluation of introgressed Nigerian dura x Deli dura oil palm progenies.

Twelve introgressed oil palm (Elaeis guineensis) progenies of Nigerian dura x Deli dura were evaluated for bunch yield, yield attributes, bunch quality components and vegetative characters at the Malaysian Palm Oil Board Research Station, in Keratong, Pahang, Malaysia. Analysis of variance revealed significant to highly significant genotypic differences, indicating sufficient genetic variability among the progenies for bunch yield and its attributes, vegetative characters and bunch quality components, except fruit to bunch ratio. Fresh fruit bunch yield ranged from 167 kg·palm(-1)·year(-1) in PK1330 to 212 kg·palm(-1)·year(-1) in PK1351, with a mean yield of 192 kg·palm(-1)·year(-1). Among the progeny, PK1313 had the highest oil to bunch ratio (19.36%), due to its high mesocarp to fruit ratio, fruit to bunch ratio and low shell to fruit ratio. Among the progenies, PK1313 produced the highest oil yield of 31.4 kg·palm(-1)·year(-1), due to a high mesocarp to fruit ratio (61.2%) and a low shell to fruit ratio (30.7%), coupled with high fruit to bunch ratio (65.6%). PK1330 was found promising for selection, as it had desirable vegetative characters, including smaller petiole cross section (27.15 cm2), short rachis length (4.83 m), short palm height (1.85 m), and the lowest leaf number (164.6), as these vegetative characters are prerequisites for selecting palms for high density planting and high yield per hectare. The genetic variability among the progenies was found to be high, indicating ample scope for further breeding, followed by selection.

Estimating aboveground biomass of oil palm: Allometric equations for estimating frond biomass

Allometric equations were developed to estimate the biomass of oil palm frond with nontree-lethal methods. The study was conducted in oil palm plantations belonging to the Oil Palm Research Center of the Institut National de Recherches Agricoles du Bénin (INRAB) and to neighboring smallholders oil palm plantations. Complete measurements of individual fronds biomass and measurements of predictor variables were made by two methods: (1) a tree-lethal (destructive) method and (2) a nontree-lethal method. Measurements were done on 25 palm trees of several ages and from different genetic origins. Frond variables measured were: length (L) and dry weight (DW) of the petiole and rachis, dry weight of leaflets, dry weight of a fragment (length=0.30m) taken from mid way along the rachis, thickness and width of the petiole cross section (junction of petiole and rachis). Linear regressions were established with biomass data obtained for different parts of the palm frond by the two methods. The results showed that up to rank 9, frond biomass increased with frond position in the crown. From rank 10, fronds were mature and their biomass showed a nearly constant value independently of rank. These results led to the establishment of a simple equation to estimate frond biomass based on rachis dry weight: DWfrond=1.147+2.135*DWrachis (R2=0.62). This relationship is closer than Corley’s one based on the cross section of the petiole (R2=0.22).Rachis dry weight can easily be estimated (R2=0.94) using rachis length and linear density (or mass per length) of a fragment of 0.30m taken from mid way along the rachis. The equation is: DWrachis=1.133∗Lrachis∗DWfragment/0.30. The study also showed that one of the applications of our allometric equations is the determination of the average dry weight of mature fronds from at least three mature fronds (rank>10). This could allow an estimate of the annual production of oil palm fronds biomass, and then the estimate of fronds carbon stock. The latter could contribute to the assessment of environmental impact of forest conversion into oil palm plantations.

Antibiosis Resistance in Soybean Plant Introductions to Dectes texanus (Coleoptera: Cerambycidae)

No soybean cultivars exhibit resistance to larval damage by the cerambycid, Dectes texanus LeConte, in the United States. Selected soybean varieties and plant introductions (PIs) in maturity groups VI to VIII from the U.S. Department of Agriculture National Soybean Germplasm Collection were evaluated for D. texanus resistance in a series of field and laboratory experiments from 2005 through 2008. In field cage experiments, the numbers of oviposition punctures (OPs) per plant were determined as indicators of oviposition antixenosis and the ratio of OPs per live D. texanus larvae (OP/Lv) served as an indicator of plant antibiosis to larvae. A D. texanus-susceptible variety treated with the systemic insecticide fipronil was used as a positive antibiosis control. Plant introduction PI165673 had the highest OP/Lv ratio, indicating that even if oviposition was successful, an antibiosis factor in PI165673 significantly reduced egg hatch and the resulting number of live D. texanus larvae. Factorial analyses indicated that maturity group is not a significant factor in the expression of resistance. Thus, PI165673 appears to be a potential source of resistance to D. texanus. In related field studies, the preferred D. texanus oviposition site was localized to leaf petioles in the upper four or five nodes of the plant canopy. Histomorphological analyses of petiole cross-sections of plant introductions PI171451, PI165676, and PI165673 indicated that leaf petiole morphology may be related to reduced D. texanus oviposition on petioles of PI171451 and PI165676, but that resistance in PI165673 is independent of petiole morphology.