Leaf Petiole Length Research Articles

Taxonomic status of <i>Pelargonium reniforme</i> Curt.

Background: Pelargonium reniforme Curt. is a morphologically variable species that many authors have attempted to split or combine. Confusion relating to the differences between the two subspecies currently included under P. reniforme has impeded attempts to assess their conservation status. Pelargonium reniforme is closely related to Pelargonium sidoides; the two species are indistinguishable when not flowering and their distributions overlap in some areas.Objectives: With this study, we aimed to clarify the taxonomic status of the two subspecies of P. reniforme, which has relevance in terms of their conservation status.Method: Leaf shape, petiole length, internode length and flower colour were assessed by studying herbarium specimens of the two subspecies of P. reniforme and specimens of P. sidoides. Living specimens of the two subspecies were also examined in their natural habitat.Results: The current investigation showed that the morphological characters used to distinguish the two subspecies of P. reniforme are too variable to separate them. Variation in some morphological characters may be related to environmental conditions.Conclusion: The recognition of the two subspecies of P. reniforme as distinct taxa is no longer justified.

Leaf morphology and anatomy of 7 varieties of Ficus deltoidea (Moraceae)

The extreme morphological variations and unclear boundaries between varieties can lead to the misleading identification of Ficus deltoidea Jack (Moraceae) varieties. This has encouraged many taxonomists and botanists to study the variation within F. deltoidea. Thus, correct identification of F. deltoidea varieties is important, as several morphological and anatomical characters are variety-specific. The present study aims to evaluate the morphology and anatomy of leaf in 7 varieties of F. deltoidea , namely var. deltoidea, var. angustifolia, var. trengganuensis, var. bilobata, var. intermedia, var. kunstleri, and var. motleyana. It also aims to contribute to the identification of the varieties based on the matured leaf characters. The results reveal varying morphological characters in the type of leaf shape, size, surface texture, margin, midrib dichotomous, and petiole length. Moreover, variations in anatomical characters concerning the structures of the lamina, leaf epidermis, and midrib are also demonstrated.

Variability in morphological characters and alkaloid profile of EMS induced mutants ofCatharanthus roseus(L.) G. Don

Seeds of Catharanthus roseus were mutagenised with ethyl methane sulphonate. On screening induced variability ten morphological variants (NV1-NV10) were isolated and their morphological variability was assessed. The hierarchical clustering analysis revealed four major groups based on morphological attributes. Genotypes with higher total alkaloid content in leaf were placed together in cluster-I and higher leaf yield plant–1, root yield plant–1 and total alkaloid content in root were placed in cluster-II. Genotypes with lowest mean values of all mentioned traits except leaf lamina width and petiole length were placed in cluster III. The consistency in performance of NV-1 and NV-10 from M1 to M3 without any significant variance in their progeny traits, showed that these were true breeding mutants. Alkaloid profiling of these ten variants was carried out by using recently developed DART MS technique. Marked variations in the alkaloid profile were also noted among them which signify the use of induced mutation in developing desirable ‘chemocultivars’.

Variability in leaf Traits of 14 Native Woody Species in Semiarid Regions of Northeastern Mexico

The present study was undertaken with the goal of analyzing the morphology and variability of leaf length, width, petiole length, and total leaf length, fresh and dry weight of individual leaves of 14 species native to Northern Mexico. The native species Cordia boissieri, Condalia hookeri, Sargentia greggii, Diospyros texana, Zanthoxylum fagara, Sideroxylon celastrinum, Karwinskia humboldtiana, Celtispallida, Guaiacum angustifolium, Prosopis laevigata, Celtis laevigata, Parkinsoniatexana, Forestiera angustifolia and Havardia pallens where chosen due to their ecological and economic importance to the rural villages as well as large variability in morphological characteristics between them. Descriptive statistical analyses showed that there was large variability in these leaf traits between the different species. Principal component analysis (PCA) revealed that it was possible to produce two axes that can explain more than 83% of the observed variation and could therefore be used in the future for separating tree species in ecological guilds and to study. Species and vegetation community level response to perturbations or individual performance in the field or under experimental conditions between the different species of this study. This suggests that similar advances are possible for other species for the same traits both in the region of study but also elsewhere.

희귀수종 먹넌출 엽의 형태적 특성과 유전변이

우리나라에서 안면도에만 분포하는 먹넌출 집단의 생명자원보존을 위하여 엽의 형태적 특성과 I-SSR 표지자를 이용한 유전변이를 조사하였다. 10가지 엽특성에 대한 ANOVA 분석결과 모든 특성에서 개체 간에 통계적인 유의성이 인정되었다. 조사된 39개체의 평균특성은 엽신장 11.8 cm, 최대엽폭 7.1 cm, 엽지수 1.67, 상1/3폭 5.4 cm, 하1/3폭 6.2 cm, 엽병길이 3.6 cm, 엽두께 0.19 mm, 엽맥수(좌) 11.5개, 엽맥수(우) 11.4개, 엽면적 61.7 <TEX>$cm^2$</TEX>로 나타났다. 변이계수 값은 엽두께, 엽병길이, 엽면적이 각각 18.8%, 21.7%, 22.0%로 높게 나타났으며, 나머지 특성들에서는 15% 이내의 비교적 낮은 변이를 나타냈다. 선발된 8개 I-SSR Primer에서 총 50개의 증폭산물을 얻었으며, 유효대립 유전자의 수 1.719개, 다형적 유전자좌의 비율 26.0%, 이형접합도의 기대치 0.410 및 Shannon의 다양성지수 0.598로 각각 나타났다. 안면도 먹넌출 집단은 제한된 지역에 분포하며 개체수가 적음에도 불구하고 높은 유전다양성을 유지하는 것으로 나타났다. This study was conducted to investigate the morphological characteristics of leaf and the genetic diversity of Berchemia racemosa var. magna which is only found in Anmyeon Island of South Korea. ANOVA test showed that there were significant differences among individuals within population in all 10 leaf characteristics. Average characteristics of 39 individuals were 11.8 cm in leaf length, 7.1 cm in leaf width, 1.67 in leaf index, 5.4 cm in upper 1/3 width, 6.2 cm in lower 1/3 width, 3.6 cm in petiole length, 0.19 mm in leaf thickness, 11.5 ea. in number of veins (left), 11.4 ea. in number of veins (right) and 61.7 <TEX>$cm^2$</TEX> in leaf area, respectively. Except for leaf thickness (18.8%), petiole length (21.7%) and leaf area (22.0%), the coefficients of variation of most leaf characteristics were relatively low (<15.0%). A total of 50 bands was generated from 8 selected I-SSR primers. The estimates of genetic variation were 1.719 in effective number of alleles (<TEX>$A_e$</TEX>), 26.0% in proportion of polymorphic bands (P), 0.410 in expected heterozygosity (<TEX>$H_e$</TEX>) and 0.598 in Shannon's diversity index (S.I.), respectively. In spite of the small number and the limited distribution, the B. racemosa var. magna population in Anmyeon Island showed high genetic diversity.

Response of leaf morphometric traits of Quercus species to climate in the temperate zone of the North-South Transect of Eastern China

Aims Plant leaf morphological traits can effectively reflect changes of plant living environments and affect the behaviors and function of plants. Our objective was to reveal the response of leaf morphometric traits of Quercus species to climate in the temperate zone of the North-South Transect of Eastern China (NSTEC). Methods We obtained leaf morphometric information by measuring plants in herbariums. We used mathematical methods of correlation analysis and standardized major axis to investigate relationships between leaf morphology and climate factors, as well as correlations among leaf morphological traits. Important findings With changing climate conditions in the temperate zone of NSTEC, leaf morphological traits of Quercus species changed significantly. Leaf area of Quercus species increased with decreased annual tem- perature and increased annual sunlight, which helps leaves to absorb more light radiation and reduce the loss of heat. The degree of leaf division can not only decrease heat dissipation from leaves, but can also enhance the fluctuation of sap flow to improve the physiological activities of leaves. Vein density increased with increased temperature and light intensity, improving the water transportation capacity, and increased with increased precipi- tation, improving the supporting ability of leaves. In addition, in order to adapt to the changed climate conditions, Quercus species built a combination of leaf morphological traits, with increased leaf area, petiole length and de- gree of leaf division, while vein density decreased. Petiole length and vein density also increased with the leaves tending toward an elongated shape.

English

The current study was done to examine the impact of ambient air pollution on some biological factors inProsopis juliflora&nbsp;plants using two sites; control and polluted (around one of the oil fields in south west of Iran). Various morphological and biochemical characteristics of the plants were studied in both sites and compared with each other. Plants exposed to pollution showed lower leaf area, petiole length, chlorophylls, carotenoids and soluble carbohydrate contents as compared to plants growing in control site. Proline levels in polluted leaves significantly increased (p &lt; 0.01), suggesting the activation of protective mechanism in these plants under air pollution stress, and also the observed responses are regarded as adaptive and compensative to the adverse effects of air pollution. &nbsp; Key words:&nbsp;Air pollution, chlorophyll, sugare, proline,&nbsp;Prosopis juliflora.

엽록체 DNA 염기서열에 근거한 물여뀌 종집단(마디풀과)의 분류학적 연구

The Polygonum amphibium complex (Poygonaceae) is a highly polymorphic taxon that can grow in aquatic environments as well as in moist terrestrial habitats. Aquatic and terrestrial plants of the P. amphibium complex vary significantly in morphology and exhibit very complicated patterns of morphological variation, resulting in the description of numerous infra-specific taxa. Principal components analysis of 107 individuals of the P. amphibium complex from Asia and North America using 11 morphological characters showed that the aquatic plants can be discerned from the terrestrial plants by leaf size, shape, and petiole length. In contrast, both aquatic and terrestrial plants collected from the same population or locality shared identical sequences in the matK, psbA-trnH IGS, rbcL-accD IGS and trnL-trnF regions of the chloroplast DNA (cpDNA), suggesting that aquatic and terrestrial forms of the P. amphibium complex are not genetically diverged; morphological differ- ences between the two forms are probably due to the differences in environmental conditions of the habitats. In addition, results from the morphological analysis and the maximum parsimony analysis of the cpDNA data set revealed that the plants from Asia including Korea, Japan, China, Mongolia and Russia Far East are diverged from those in North America and Europe, suggesting that the Asian populations should be recognized as a dis- tinct variety, P. amphibium var. amurense Korsh.

Comparison of Nine Clones of ‘Jewel’ Strawberry in Ontario and Nova Scotia

Nine clones of ‘Jewel’ strawberry, all originating from the same source in 1997, and propagated at one location in 2008, were compared in replicated trials planted in Kentville, NS and London, ON in 2009. Six of the clones were from micropropagated plants in Ontario, two were from runner-propagated plants, and the last was from the nursery that had provided the original stock. Data on vegetative and reproductive factors were recorded at both sites in 2009 and 2010. The number of runners, leaf petiole length, and the severity of powdery mildew were recorded 60 days after planting. Plot fullness was rated the first fall and the following spring. In the spring of the second year, plant vigor, phenology, and the number of flower stalks and flowers per stalk were recorded. Fruit yield, whether marketable or unmarketable, and berry counts were recorded twice weekly in the second year. Clonal differences were noted in all the plant measurements. For example, one of the runner-propagated ‘Jewel’ clones, JEEL 9, had the highest number of runners and the longest petioles. Site x clone interactions were significant for spring vigor and spring plotfill ratings and for the number of flower stalks. Differences in flower development were also noted, however, there were no significant differences in harvest date. There was a small but significant difference in berry weight but not in marketable or total yield. The clonal variation described in this study was not of sufficient scope to explain the poor crops that some growers have occasionally reported. Alternative explanations are offered.

Keys for and morphological character variation in some Egyptian cultivars of Cucurbitaceae

The cultivated varieties and landraces of Cucurbitaceae growing in Egypt are presented, 27 taxa, belonging to three genera, six species, and five subspecies. These characters are arranged according to their usefulness for identifications as follow: fruit characters, seed characters and trichome type. Fruit characters are a good taxonomic tool at varietal level when combined with the other vegetative characters. Two keys to 27 cultivated varieties of Cucurbitaceae (Cucumis, Cucurbita and Luffa) were constructed using the DELTA software system. One key is used for identification, and then the other is used as a confirmatory key. Those keys were built using 36 morphological characters include vegetative, floral, fruit and seed characters. There is a significant correlation between seed size and growth parameters. The growth parameters of the studied taxa included leaf length/size, petiole length and corolla length. There is a highly positive, significant correlation between seed volume and leaf size (r = 0.81831, P ≤ 0.001), seed volume and petiole length (r = 0.79112, P ≤ 0.001), seed volume and leaf length (r = 0.83566, P ≤ 0.001), and seed volume and corolla length (r = 0.59108, P ≤ 0.001).

A Study of Morphophysiological Descriptors of Cultivated Anthurium andraeanum Hort.

Sixteen morphophysiological parameters of horticultural importance were investigated in 82 anthurium accessions grown in the Caribbean. The spathe colors included red, pink, white, green, orange, purple, coral, and brown and obake types with red, pink, and white spathe colors accounting for 63.4% of the accessions. There was wider variation in spadix color combinations than spathe color. There was wide variation for the cut flower and leaf parameters evaluated with productivity and peduncle length having the smallest and largest range, respectively. The frequency distributions were skewed to the right for spathe length, spathe width, spathe size, spadix length, spadix diameter, leaf width, leaf size, and productivity and was normal for leaf length, spadix angle, peduncle length, petiole length, and spathe showiness. Accessions with wider leaves had longer leaves and longer petioles; those with longer spathes had wider spathes; and those with longer peduncles had correspondingly longer petioles. Peduncle length also showed moderate, weak correlations with other leaf measurements and spathe parameters, respectively. Spadix diameter showed moderate correlations with leaf parameters. Spathe showiness showed moderate, weak correlations with spathe measurements and productivity, respectively. Principal component analysis of the 13 quantitative parameters showed that the first three principal components explained 75% of the variation in the accessions. Leaf length, leaf width, leaf size, petiole length, peduncle length, and spadix diameter; spathe length, spathe width, spathe size, and spathe showiness; and productivity loaded on the first, second, and third component, respectively. Hence, one leaf and one spathe size parameter, spathe showiness, petiole length, peduncle length, spadix length, spadix angle, spadix diameter, and productivity as well as spathe, spadix, peduncle, and petiole colors can be used as descriptors for anthurium. Based on these results and market information, an Anthurium ideotype adapted to the humid tropics is described.

Birds see the trees inside the forest: The potential impacts of changes in forest composition on songbirds during spring migration

Since European settlement, hardwood dominated forests of the Upper American Midwest have undergone compositional changes due to fire suppression and changes in land use. It is not clear how these changes affect songbirds during spring migration. In 2009 and 2010, we quantified foraging behavior by migratory songbirds during spring migration and collected data on tree and sapling diversity in the Kickapoo Valley Reserve in southwestern Wisconsin. Furthermore, we compared the 1840s distribution of tree species (from Public Land Survey System witness tree records) with current (2010) and estimated future (sapling) tree-composition to better understand how historic and future changes in tree composition may impact migratory songbirds at spring migration stopover sites. Six tree species were selected as foraging substrates in higher proportion than they were available by eight migratory songbirds, including trees adapted to moderate shade such as northern red oak (Quercus rubra), white oak (Quercus alba), American elm (Ulmus americana), and slippery elm (Ulmus rubra), and shade-intolerant species such as big-tooth aspen (Populus grandidentata), and paper birch (Betula papyrifera). Whereas three shade-tolerant tree species were selected in far lower proportion than they were available by eight migratory songbirds, including sugar maple (Acer saccharum), red maple (Acer rubrum), and basswood (Tilia americana). We found evidence that food accessibility, as measured by a novel approach relating a bird’s attacks and search efforts to the average leaf petiole length of a tree species, was strongly inversely related with a bird’s foraging success (ρ=−0.96, p-value <0.001). Although tree-species composition changed considerably from the 1840s to 2010, in both time periods the forest was dominated by a mix of sugar maple and oak species. However, sugar maple saplings currently form a nearly continuous layer in the understory and there is very low recruitment of shade-intolerant or moderately shade-tolerant species, suggesting a future shift towards dominance by shade-tolerant species. Our results suggest the current trajectory of forest succession may result in future conditions that provide lower quality foraging for migratory songbirds during spring migration than they currently experience in the Upper American Midwest.

Sodium Azide Induced Morphological and Molecular Changes in Persimmon (Diospyros Lotus L.)

Sodium Azide Induced Morphological and Molecular Changes in Persimmon (Diospyros LotusL.)PersimmonDiospyros lotusL. is an underutilized species, used as rootstock for Japanese persimmon (Diospyros kakiThunb.) in many European countries. It has a potential for ornamental uses due to its diploid genome that suggests an easy mutation induction. This study was aimed at unravelling the effects of mutagenic sodium azide (in concentrations of 0.1% and 0.5%) on morphological characters (plant height, maximal leaf blade length, maximal leaf blade width and leaf petiole length) and molecular relations of treated accessions, based on AFLP (amplified fragment length polymorphism). In the M1 generation, the analysed characters of two-year old plants differed among the treatments. Sodium azide influenced persimmon stem and leaves in the opposite way, with increase up to 31.57% in plant height and decrease up to 30.33% in leaf petiole length. Changes in morphological characters were significant, that implies the importance of azide influence on the persimmon. Most genotypes treated with 0.1% azide were without significant differences among them and clustered together. The results suggest that the higher azide concentration of 0.5% is more suitable for persimmon seeds azide treatment to form genotypes, significantly different from the control, at the molecular level.

Assessment of genetic diversity in horticultural and morphological traits among papaya (Carica papaya) accessions in Nigeria

Introduction . Although Nigeria has the largest area planted to papaya (Carica papaya ) in the world, this country has one of the lowest yields reported. A good knowledge of the available genetic variability is a first step in the exploitation of this crop for the development of improved cultivars. Until now, there has been no report on genetic diversity in the papaya accessions available in Nigeria. Materials and methods . Sixty accessions of papaya obtained from ten districts in Southeastern Nigeria were evaluated using 21 variables following the IBPGR descriptors for papaya. The data was subjected to descriptive statistics, analysis of variance (ANOVA), and multivariate analysis including principal component (PCA) and cluster analysis. Results . ANOVA showed significant variation among accessions in fruit length, fruit diameter, fruit edible volume, leaf petiole length, fruit shape, flesh color and central cavity shape. The first seven principal component axes accounted for 73.47% of total variation and five cluster groups were generated from cluster analysis. Accessions were classified into two broad groups corresponding to female (15%) and hermaphrodite (85%) plants. A strong and highly significant correlation was found between leaf blade and petiole length and fruit characteristics such as length, diameter and fruit edible volume, a variable derived for the first time in this study. There was a preponderance of yellow flesh color in fruits from female plants and reddish-orange flesh color among hermaphrodite plants. Discussion and conclusions . Each of the five cluster groups consists of accessions that could be used as parents in further breeding or clones for vegetative propagation. This study revealed significant variation that could be exploited for genetic improvement of papaya in Nigeria. It is recommended that a focused papaya genetic improvement program should be pursued to exploit the genetic variation available.

FOLIAR RESPONSES OF TREE SEEDLINGS TO DIFFERING LIGHT AND TOPOGRAPHIC POSITIONS IN A SINHARAJA FOREST

Light is one of the most demanding and limiting factor in the lowland rain forests. Here we studied seedling foliar responses (anatomy and morphology) of nine tree species in genera Shorea, Dipterocarpus, Mesua and Syzygium to different light environments (gap and understory) across three topographies (valley, midslope and ridge). There were significant differences in anatomical and morphological trails among species due to differing light and topographic positions. All species had higher anatomical (thickness of leaf blade, upper and lower epidermis cell years, palisade mesophyll cell layers, cuticle layer thickness and stomatal density) and leaf morphological tails ( single leaf area, length, width, drip-tip length and petiole length) in canopy gaps than in the understory. Among the species Syzygium makul had the thickest leaf blade in all gaps of each topography. Shorea megistophylla had thickest upper epidermal in two lights and across topographies. Shorea disticha andShorea megistophylla showed thickest palisade layer. S. makul was greater in stomatal density (number of stomata per unit area). Shorea megistophylla and D.s zeylanicus showed higher leaf area than other species. When compared the measured foliar responses S. megistophylla is most suitable for valley, while D. zeylanicus, M. ferrea, S. makul and S. rubicundum for mid-slope sites. Mesua nagassarium, S. worthingtonii for ridge tops in both gap and the understory light environments. Finding indicate that the foliar traits are partially important in determination of species adaptation to particular light environment within the rain forest.

Influence of Substrate Water Content and Daily Light Integral on Photosynthesis, Water Use Efficiency, and Morphology of Heuchera americana

Two investigations were conducted to determine the morphological and physiological impacts of varying light and substrate water levels on Heuchera americana ‘Dale's Strain’ (american alumroot). Both investigations used a capacitance sensor automated irrigation system to maintain constant substrate volumetric water contents (θ = volume of water/volume of substrate). In the first study, the substrate was maintained at one of eight θ ranging from 0.15 to 0.50 L·L−1. Leaf area of plants grown at the highest θ was more than twice that of plants grown at the lowest θ. Shoot dry weight also responded positively to θ increasing from 0.15 to 0.35 L·L−1, but plants did not have greater dry weights when maintained at θ higher than 0.35 L·L−1. The second experiment assessed american alumroot's performance under four daily light integrals (DLIs) (7.5, 10.8, 14.9, and 21.8 mol·m−2·d−1) with θ maintained at 0.35 L·L−1. Increasing DLI from 7.5 to 21.8 mol·m−2·d−1 caused shoot dry weight, leaf area, maximum width, and leaf count to change quadratically. Dry weight and leaf area reached their maximum at 10.8 mol·m−2·d−1, whereas leaf count was greatest at 14.9 mol·m−2·d−1. Increasing DLI to 21.8 mol·m−2·d−1 negatively impacted leaf area and leaf count but did not lower shoot dry weight. Leaf area ratio and petiole length of the uppermost fully expanded leaf decreased with increasing DLI. Measures of leaf-level net photosynthesis, light response curves, and CO2 response curves indicated no physiological differences among plants grown under different water or light levels. In both studies, long-term, whole crop measures of water use efficiency based on shoot dry weight and water applied (WUEc) did not reflect the same water use trends as instantaneous, leaf-level measures of WUE based on leaf gas exchange (WUEl). WUEc decreased with increasing θ and DLI, whereas WUEl was not influenced by θ and increased with increasing DLI. WUEl is often used to provide insight as to how various abiotic and biotic factors influence how efficiently water is used to produce biomass. However, these findings demonstrate that there are limitations associated with making such extrapolations.

Comparison of East and West African populations of baobab (Adansonia digitata L.)

The baobab tree (Adansonia digitata L.) is of large socioeconomic importance. However, domesticated plant material of baobab is rarely available to African farmers, and very limited pre-breeding knowledge is available. To evaluate genetic differentiation between geographical origins we compared vigor and leaf morphology of trees from 17 West African and 13 East African provenances of baobab. Seedlings were grown and evaluated in a common garden test at Bamako, Mali. Germination was assessed and growth measured 3 and 12 months after germination. Leaf morphology (leaf length, leaflet number, petiole length and diameter and leaflet border) were assessed after 12 months. Significant differences between the provenances were observed for both growth rate and leaf morphology. West African provenances in general grew faster than East African provenances, but leaf characters did not reveal a particular geographic structure, and the correlations between geographic distances and multivariate Mahalanobis distances were not significant. The correlations between leaf morphological traits and climatic data were in general low at the provenance level. However, the number of leaflets was significantly higher for provenances from drier areas. Two years increment at a field site also varied significantly between the provenances, where West African provenances confirmed their tendency to higher growth rate. Still, trees are young and results regarding both growth data and leaf characteristics should be confirmed when the trees are closer to maturity.

Developing mutant sunflower lines (Helianthus annuus L.) through induced mutagenesis and study of their combining ability

Immature sunflower (Helianthus annuus L.) zygotic embryos of sunflower double haploid fertility restorer line 381 R were treated with ultrasound before planting to embryo culture medium. Some mutant plants were isolated and self-pollinated for several generations. New sunflower forms with inherited morphological, biochemical and phytopathological changes were obtained through selection and self-pollination. The genetic changes included 12 morphological and biochemical agronomic traits. In our study the plant height, leaf petiole length, 1000-seed weigh, as well as oil content in them were most unstable, based on all investigated characteristics. In comparison to the control 381 R, decreasing in the mean value of the indexes was registered for 66.7% of the total number of characteristics and vice verse, significant increasing for the number of branches and oil content in seed i.e., 16.7%. Stability after induced mutagenesis was demonstrated by the characteristic number of leaves. This index was not affected by the changes in climatic conditions. Mutation for resistance to Plasmopara halstedii (Farl.) was obtained from the susceptible Bulgarian control line 381 R. Reduction of plant height, increasing oil content in seeds, very good combining ability, resistance to Plasmopara halstedii, as well as to the parasite Orobanche cumana of the new mutant lines is a desirable combination in the breeding program of sunflower. Hybrids No. 15, No. 16 and No. 17, developed with the participation of lines No. 97, No. 100 and No. 101 considerably exceeded the mean standard (commercial hybrids San Luka, Maritza and Mura) by seed and oil yield. Ultrasound in sunflower can be successfully used to develop new mutant lines useful for heterosis breeding.

Ontogenetic variations in flush development are indicative of low temperature tolerance in Hevea brasiliensis clones

Para rubber (Hevea brasiliensis) trees are naturally adapted to the Amazonian tropical climate. In India rubber trees are traditionally cultivated in the warm humid tropics of the south. Northeast India is a non-traditional area for rubber cultivation. A major limiting factor on tree growth in the northeast region is stress due to low temperature. Being a deciduous tree, rubber trees exhibit annual natural defoliation prior to the winter season, and ensuing new leaf growth usually coincides with the low temperature period. Flushing behaviour of trees during this period provides an opportunity to assess their winter hardiness. A study was carried out on five clones, RRIM 600, SCATC 93/114, GT 1, PB 5/51 and Haiken 1, to evaluate phenological behaviour of leaf growth during the period of low temperature stress. Trees were monitored for expansion of leaf area, internode length, petiole length and development of chlorophyll. Wide variation was observed among these clones for all the traits. SCATC 93/114 was better adapted for low temperature stress as this clone was found to have faster expansion of leaf area and better chlorophyll development, followed by Haiken 1. PB 5/51 was found to show poor performance during low temperature. Haiken 1 and PB 5/51 also exhibited better relative growth rate during winter months confirming their low temperature tolerance. Ontogenetic variations in leaf development are good indicators of assessing inherent cold tolerance in Hevea clones.

Morphoagronomic variation in natural populations of Trifolium riograndense (Burkart)

Several species of Trifolium are widely cultivated as forage for animals and green manure. This work aimed to characterize and estimate through morphological and agronomic traits the genetic diversity of natural populations of T. riograndense, an important forage legume from native pastures of the state of Rio Grande do Sul, Brazil. Plant height and diameter, number of primary and secondary stolons, stolon length, number of nodes per primary stolon, internode length, primary stolon diameter, leaf area, petiole length and dry matter production were analyzed in 29 accessions. The first five attributes and dry matter production were evaluated twice. A broad phenotypic variability was observed for almost all characteristics. Positive correlations occurred between petiole length and leaf area (r = 0.68), petiole length and plant height in the first evaluation (0.63), stolon length and plant height (0.58), total dry matter and plant diameter (0.61), and total dry matter and plant height in the second evaluation (0.55). The two most divergent accessions were collected in the same physiographic region and the two less divergent ones in different regions. A dissimilarity dendrogram separated four groups. Accessions collected in a region where T. riograndense is abundant were found to belong to different groups outlining the great variability of this native forage legume. Dry matter production in the first cut was the characteristic that most contributed (20.80%) to accessions divergence followed by number of secondary stolons (12.30%), leaf area (11.07%), and number of nodes per primary stolon (10.93%).