Showing papers on "Plant morphology published in 2011"

Heavy metals accumulation in plants growing in ex tin mining catchment

Abstract: The degree of contamination by heavy metals (arsenic, copper, lead, tin and zinc) in soil and transfer to plants has been studied. Specimens of plant species from five locations in an area of 10 x 10 m were sampled with their corresponding soils. Thirty six plant species including two shallow water aquatic plants were identified. Soil and plant specimens were analyzed by using inductively coupled plasma optical emission spectrometry. It was found that metal concentration in soil was highly variable while concentration of metals in plants directly depends on the concentration of metals it was rooted. Roots showed highest metal concentration followed by leaves, shoots and flowers. Bioconcentraion factor and translocation factor were calculated, representing Cyperus rotundus L. as a potential tin-hyperaccumulator plant, previously not reported in literature. Plant Species Imperata cylindrica, Lycopodium cernuum, Melastoma malabathricum, Mimosa pudica Linn, Nelumbo nucifera, Phragmites australis L., Pteris vittata L. and Salvinia molesta, were metal accumulator while Acacia podalyriaefolia G. Don, Bulb Vanisium, Dillenia reticulate King, Eugenia reinwardtiana, Evodia roxburghiania Hk. f. clarke, Gleichenia linearis, Grewia erythrocarpa Ridl., Manihot esculenta Crantz, Paspalum conjugatum Berguis, Passiflora suberosa, Saccharum officinarum, Stenochlaena palustris (Burm.) Bedd. and Vitis trifolia Linn. were tolerated plant species. All other studied plants were excluders. Identified plant species could be useful for revegetation and erosion control in metals contaminated ex-mining sites. Morphological changes such as reduction in size, change in color and deshaping have also been observed in plant species with high metal values.

PREFACE: PART OF A SPECIAL ISSUE ON FUNCTIONAL -STRUCTURAL PLANT MODELLING Using functional-structural plant models to study, understand and integrate plant development and ecophysiology

Abstract: Functional–structural plant models (FSPMs) explore and integrate relationships between a plant’s structure and processes that underlie its growth and development. In recent years, the range of topics being addressed by scientists interested in functional –structural plant modelling has expanded greatly. FSPM techniques are now being used to dynamically simulate growth and development occurring at the microscopic scale involving cell division in plant meristems to the macroscopic scales of whole plants and plant communities. The plant types studied also cover a broad spectrum from algae to trees. FSPM is highly interdisciplinary and involves scientists with backgrounds in plant physiology, plant anatomy, plant morphology, mathematics, computer science, cellular biology, ecology and agronomy. This special issue of Annals of Botany features selected papers that provide examples of comprehensive functional –structural models, models of key processes such as partitioning of resources, software for modelling plants and plant environments, data acquisition and processing techniques and applications of functional– structural plant models for agronomic purposes.

Tradeoff between biomass and flavonoid accumulation in white clover reflects contrasting plant strategies.

Abstract: An outdoor study was conducted to examine relationships between plant productivity and stress-protective phenolic plant metabolites. Twenty-two populations of the pasture legume white clover were grown for 4½ months during spring and summer in Palmerston North, New Zealand. The major phenolic compounds identified and quantified by HPLC analysis were glycosides of the flavonoids quercetin and kaempferol. Multivariate analysis revealed a trade-off between flavonoid accumulation and plant productivity attributes. White clover populations with high biomass production, large leaves and thick tap roots showed low levels of quercetin glycoside accumulation and low quercetin:kaempferol ratios, while the opposite was true for less productive populations. The latter included stress-resistant ecotypes from Turkey and China, and the analysis also identified highly significant positive relationships of quercetin glycoside accumulation with plant morphology (root:shoot ratio). Importantly, a high degree of genetic variation was detected for most of the measured traits. These findings suggest merit for considering flavonoids such as quercetin as potential selection criteria in the genetic improvement of white clover and other crops.

Path Analysis of the Relationships between Yield and Some Related Traits in Diallel Population of Sunflower ('Helianthus annuus' L.) under Well-Watered and Water-Stressed Conditions

Abstract: In order to study the association among yield components and their direct and indirect effects on the seed yield of sunflower under well-watered and water-stressed conditions, six sunflower inbred lines and their 15 F1 hybrids were investigated using a randomized complete block design with three replications in each water treatment conditions. Different traits such as: chlorophyll content (CC), head diameter (HD), head weight (HW), leaf number (LN), aerial part dry weight (APDW), number of achene (NA), plant height (PH) and seed yield per plant (SY) were measured. Morphological traits were measured in full flowering stage and traits related to seed were recorded after seed harvesting. Genotypic correlations manifest that seed yield per plant was positively and significantly associated with head diameter, plant height and number of leaf and achene traits at well-watered condition. While, in the water-stressed state, head weight, head diameter, number of achene and chlorophyll content showed positive and significant correlation with seed yield per plant. Path coefficient analysis revealed that traits including head diameter and number of achene in both conditions and chlorophyll content in water-stressed condition have positive direct effect on seed yield per plant. Therefore, selection based on these traits would be more effective to improving seed yield of sunflower in well-watered and water-stress conditions.

Investigation and comparison of some morphological traits of the soybean populations using cluster analysis

Abstract: A study was performed on 92 genotypes of soybean including 4 checks during the Kharif season (July-Oct) of 2003. High values of the Shannon index for flower colour (0.54), pod colour (1.12), plant type (0.88), seed luster (0.84), seed size (1.08) and seed colour (0.91) revealed greater variability in these qualitative traits. High CVs were recorded in leaf area (44.81%), pods plant -1 (29.47%), branches plant -1 (31.72%), 100-seed weight (39.01%) and grain yield plant -1 (46.55%) with a wide range of 28-146, 26-130, 2.4-11, 4.2-21.5 and 4.04-28.23 respectively indicating a high level of diversity among the accessions for these traits. Grain yield was positively and highly significantly correlated with leaf area, plant height, pods plant -1 , branches plant -1 and 100-seed weight suggesting thereby that phenotypic selection could be made on the basis of these characters. Means of the clusters showed that the accessions in cluster III were not only late maturing and high yielding but also had more pods plant -1 , branches plant -1 and 100-seed weight. However, accessions in cluster I showed some promise to earliness with high grain yield and oil. The physical distinctness, on the basis of cluster analysis, between Pakistani and US/AVRDC accessions in this study reflect that the introgression of US and AVRDC accessions to Pakistani breeding programme should broaden Pakistani soybean germplasm diversity. Whereas no clear relationship was found between genetic diversity and geographical origins because accessions from one origin entered into more than one cluster.

Phenotypic plasticity of Vaccinium meridionale (Ericaceae) in wild populations of mountain forests in Colombia

Abstract: Vaccinium meridionale is a promising crop for the Andean region of South America and is currently available only in the wild. Spontaneous populations of this plant are found across the Colombian mountains, but very few published records on this plant morphology are available. A zonification study of V. meridionale was conducted in four principal areas of a low mountain forest of Colombia (Provinces of Boyaca, Cundinamarca, Santander and Narino) in 2007. A total of 20 populations and 100 plants of V. meridionale were individually characterized and surveyed, using a list of 26 characters of morphological variables (9 quantitative and 17 qualitative characters). Our results indicated that natural populations of V. meridionale might be found in the tropical forest under a highly heterogeneous climate and microclimate conditions, at different mountain regions between 2 357 and 3 168masl. The shrubs of V. meridionale exhibited a high level of intra-population variation in several quantitative (plant height, stem diameter) and qualitative (growth habit, ramification density, presence of anthocyanins in stems) morphological characters, suggesting an environmentally induced phenotypic plasticity. Plant height, stem diameter and foliar density were the most variable morphological traits, with coefficients of variation higher than 50%. However, several quantitative characters of its reproductive potential, such as berry dimensions, rachis length and number of flowers per inflorescence, resulted with low plasticity with coefficients of variation lower than 30.2%, indicating that these characters were genetically determined. The highest correlation coefficients (p < 0.05) resulted to be between fruit length and fruit width (0.90), leaf length and leaf width (0.78), plant height and stem diameter (0.60), and inflorescence length and flowers number per inflorescence (0.57). The results suggest that an important genetic resource exists for this species in the wild. Low variation in fruit size, which constitutes a target trait for plant breeders, could be useful for selection of cultivars of V. meridionale. The results of this study could also be applied in conservation programs aimed to protect these diverse populations in the mountain forests of Colombia.

Response of Trifolium repens to UV-B radiation: morphological links to plant productivity and water availability.

Abstract: This study used nine populations of Trifolium repens L. (white clover) to investigate possible relationships between plant morphological attributes and responses to ultraviolet-B (UV-B) radiation. Plants were exposed to 0 or 13.3 kJ·m(-2) ·day(-1) UV-B for 12 weeks. Drought was applied in parallel to these treatments during the last 4 weeks of the experiment to test whether limited moisture availability would alter morphological UV-B responses. UV-B affected plant morphology under well-watered conditions, reducing leaf size by 15%, leaf number by 5% and stolon elongation by 19%. The number of leaf primordia in the apical bud was decreased by 4% under UV-B, and by 12% under drought. In drought-exposed plants, leaf size was reduced by 50%, leaf number by 30% and stolon elongation by 60%. In addition, drought reduced specific leaf area (SLA) by 33% and increased leaf percentage dry mass (PDM) by 40%. UV-B-induced reduction in plant biomass in the T. repens populations was associated with higher plant productivity and this was further linked to larger leaf size as well as to lower PDM. In conclusion, the findings suggest that morphological attributes conferring fast potential growth under productive conditions carry a cost in the form of lower biomass accumulation under UV-B.

The morphological traits of needles as markers of geographical differentiation in European Pinus sylvestris populations

Abstract: To evaluate the geographic variability of Pinus sylvestris populations seven morphological traits of needles of pines from IUFRO 1982 provenance trial have been analyzed. The studied populations originated from northern (>55°N in Russia, Sweden and Latvia), central (55-47°N in Poland, Germany, Belgium, France, Slovakia) and southern (<47°N in Hungary, Bosnia, Montenegro and Turkey) European ranges of Scots pine. The analyzed provenance trial experimental areas were located in Kórnik (western Poland) and in Supraśl (north-eastern Poland). The greatest variation was found in needle length and number of stomata rows on the flat and convex side of a needle, whereas number of stomata per 2 mm of needle length on flat and convex side of a needle was stable, with minor interpopulational variation. Biometrical analyses revealed a significant population × location interaction and a geographical pattern in interpopulational differentiation in both experimental sites, with the northern and southern European Scots pine groups of provenances differing significantly from the group of central origin. The results obtained are compatible with previous results of studies on provenance variability of the Scots pine from IUFRO 1982. In the light of available data, the influence of the Balkan glacial refugia of Pinus sylvestris on a present genetic diversity of this species in Europe and the reconstruction of Scots pine migration routes after the last glacial period are discussed. Additional key words: interpopulational variability, migration routes, population × location interaction,

Host plant selection and oviposition behaviour of whitefly Bemisia tabaci (Gennadius) in a mono and simulated polyculture crop habitat

Abstract: The host plant selection, oviposition behaviour and survivorship of whitefly ( Bemisia tabac i (Gennadius) was evaluated in green house. Three host plants cultivars namely: Brinjal ( Solanum malagna ), chilli ( Capsicum annuum ) and tomato ( Solanum lycopersicu m) were placed in a multiple crop habitat at 34 - 36°C, 70 - 80% relative humidity (RH) in a normal day light. There was a variation of morphological characteristic among host plants (smooth and thick trichome leaves) where all developmental stages of pest were given free choice of foraging. Although the host plants genus C. annum and S. lycopersicum were also the potential host of B. tabaci but in the presence of S. malagna, the attack rate remains minimum on both the host plants. The feeding and egg laying was significantly higher on S. malagna L . leaves as compare to other two host plants in the open arena. S malagna L. was also preferred when pest was tested in confined cages for free choice probing on capsicum and S. malagna L. There was no significant but a slight difference in survivorship of all developmental stages of whitefly when Brinjal and Chilli and then Brinjal and tomato from two different experimental arenas were compared. There was no host plant varietal effect on the overall developmental time from egg eclosion to the adult. The leaves of S. malagna with thick trichomes were chosen significantly more higher for egg laying compared to other host plants. The morphological characters and plant architecture contribute to higher densities of adult whitefly (wf) compared to new leaves. No symptoms of viral infection has been observed on the chilli with Brinjal, whereas, the same variety of chilli was reasonably infected with virus in chilli monocrop arena. Key words: Multiple cropping, host plant selection, oviposition fecundity, intrinsic rate of increase.

Overexpression of Petunia SOC1-like Gene FBP21 in Tobacco Promotes Flowering Without Decreasing Flower or Fruit Quantity

Abstract: FBP21 is one of the SOC1-like genes isolated from Petunia hybrida. Based on sequence analysis, FPB21 is suggested to have a role in promoting flowering. In this study, FBP21 was expressed in a tobacco host plant under the control of the CaMV 35S promoter. Our results showed that the transgene accelerated flowering, i.e. the transgenic plants flowered just 3 months after germination, in comparison to the wild-type tobacco which flowered after 5 months. Plant morphology was also affected, with the transgenic tobacco plants developing at least five robust lateral branches, while the control plants generally had just three. Total leaf area was significantly reduced in the transgenic tobacco compared to wild-type tobacco. By contrast, there was no significant difference between transgenic and control plants for the total number of flowers or fruits. Thus, the flower or fruit yield expressed per unit leaf area was higher in transgenic tobacco than in wild-type plants. Semi-quantitative RT-PCR analysis indicated that overexpression of FBP21 in tobacco resulted in the up-regulation of some flowering-related genes. The results of this study in tobacco indicate that the Petunia FBP21 gene may permit the engineering of early-flowering and short-growth habits without compromising flower or fruit yields.

Morphogenesis of Tanzania guinea grass under nitrogen doses and plant densities

Abstract: The objective of this work was to evaluate effects of nitrogen fertilization and plant density on morphogenesis of Tanzania guinea grass. It was used a random block design with 12 treatments and two replications in a 4 × 3 factorial arrangement, with four doses of nitrogen (N) (without N application, 80, 160 or 320 kg/ha.year) and three plant densities (9, 25 or 49 plants/m2). Harvest was performed at 25 cm from the ground when the canopy intercepted 95% of the incident light. Rates of leaf appearance and pseudostem elongation were positively and linearly influenced by nitrogen, whereas phillochron and leaf life span were influenced linearly and negatively. Leaf elongation responded positively to two factors, whereas leaf senescence rate and number of live leaves were not influenced by the factors evaluated. Number of total, basal and aerial tillers were greater at the density of 9 plants/m2 and at the nitrogen dose of 320 kg/ha.year. Nitrogen increases production of leaves and tillers in Tanzania guinea grass defoliated at 95% of light interception, but high density of plants reduces the number of tiller per bunch.

Morphological and physiological traits associated with seed yield in different chickpea (Cicer arietinum L.) genotypes under irrigated and water-deficit environments.

Abstract: The morpho‐physiological traits associated with seed yield in chickpea (Cicer arietinum L.) were evaluated on thirty fiv e chickpea genotypes under two different water regimes. In optimum condition, the highest correlation was belonged to number of seeds/plant and number of pods/plant (0.944**) and in water deficit condition, the strongest correlation of seed yield was ob‐ served with number of seeds/plant (0.875**), number of pods/plant (0.789 **) and 100‐seed weight (0.438**). Physiological traits (RWC, Chloro‐ phyll and Carotenoid) indicated low and positive correlation with yield, but high positive correlation with other seeds yields related traits in optimum condition while, under water deficit condition, chlorophyll content and RWC had low and non‐significant negative correlation with seeds yield. Carot e‐ noid, number of seeds/plant and 100‐seed weight showed more direct posi‐ tive effect on yield in optimum environment and in stress condition, number of seeds/ plant and 100‐seed weight showed highest direct effect on seed yield. Results of factor analysis showed that four factors explained 88.54% and 34.5% of the total variance cause d in the characters in optimum and water deficit environment, respectively. In general, the results suggested that a chickpea cultivar, for increased yield under non‐stress conditions, should have maximum number of seeds and pods per plant and under stress conditions should have maximum number of seeds and pods per plant and also keep the high level of RW C and chlorophyll content in their leaves. Thus, identifying these traits as selection criteria in chickpea breeding program may be useful for breeders to introduce suitable drought resistant chickpea cultivars for arid regions.

morphological variation of the leaves of Aechmea distichantha Lem. plants from contrasting habitats of a Chaco forest: a trade-off between leaf area and mechanical support

Abstract: Several authors have reported phenotypic plasticity for bromeliad plants growing in contrasting habitats. Morphological and physiological differences of leaves seem to be an adaptation to water and light use, but there is also a compromise between carbon gain and the costs of sustaining static and dynamic loads. We hypothesized that plastic responses to habitat at the leaf level represent a trade-off between the photosynthetic area for capturing light and mechanical support. In this study, we measured morphological and architectural variables of central and basal leaves of Aechmea distichantha plants from the understory and forest edge, as well as anatomical variables of plants from each habitat. Understory plants had longer leaves, larger blade areas and greater length/width ratios than forest-edge plants. Blades of understory plants were less erect, less succulent, had thicker fiber tissue surrounding the vascular bundles and a higher curvature index than blades of forest-edge plants. Thus, understory plants increased their flexural stiffness by modifying their tissue structure as well as the shape of their leaves. On the other hand, blades of forest-edge plants had higher stomatal density and higher trichome density on their adaxial sides than understory plants. These patterns could be adaptations for higher gas exchange and to reduce vulnerability to photoinhibition in sun plants when compared to shade plants. Finally, most of the morphological and architectural variables were significantly different between positions. These results support our view that there is a trade-off at the leaf level between photosynthetic leaf area (for light capture and water use) and mechanical support.

Structural and physiological sexual dimorphism estimated from three-dimensional virtual trees of yerba-mate (Ilex paraguariensis) is modified by cultivation environment

Abstract: Yerba-mate is a subtropical, evergreen, dioecious, South American tree. Sexual dimorphism in photosynthesis, leaf allometry and foliage distribution was hypothesised. Virtual trees (constructed in VPlants software from detailed measurements of plant morphogenesis) of the two genders were compared considering two contrasted cultivation environments and three developmental stages. The total crown volume, leaf area per plant (LA), leaf area index (LAI) and leaf area density (LAD) were calculated. The light interception and photosynthesis were computed from mock-ups in VegeSTAR. Structural sexual dimorphism concerned general plant form, internode length, leaf allometry, leaf surface, pattern of leaf area distribution and LAD. Cultivation environment and developmental stage acted strongly on sex expression of all observed structural parameters and physiological stages. Sexual differentiation in LA and light interception was related to leaves positioned in the lowest layers (150 cm above ground), whereas sexual specialisation in leaf and plant photosynthesis was related to early vegetative and reproductive stages. Several sexual responses strongly depended on the environment, especially light conditions, with opposite effects observed on female and male plants whether they were cultivated in monoculture or in forest understorey, under highlight condition or low-light condition, respectively. Optimised foliage structure and physiology in females may compensate for greater reproductive costs in early developmental stages, but females and males equalise in photosynthetic efficiency after 2-year regrowth.

Influence of environmental changes on physiology and development of polar vascular plants

Abstract: Polar vascular plants native to the Arctic and the Antarctic geobotanical zone have been growing and reproducing effectively under diffi cult environmental conditions, colonizing frozen ground areas formerly covered by ice. Our macroscopic observations and microscopic studies conducted by means of a light microscope (LM) and transmission electron microscope (TEM) concerning the anatomical and ultrastructural observations of vegetative and generative tissue in Cerastium arcticum, Colobanthus quitensis, Silene involucrata, plants from Caryophyllaceae and Deschampsia antarctica, Poa annua and Poa arctica, from Poaceae family. In the studies, special attention was paid to plants coming from diversity habitats where stress factors operated with clearly different intensity. In all examinations plants, differences in anatomy were considerable. In Deschampsia antarctica the adaxial epidermis of hairgrass leaves from a humid microhabitat, bulliform cells differentiated. Mesophyll was composed of cells of irregular shapes and resembled aerenchyma. The ultrastructural observations of mesophyll in all plants showed tight adherence of chloroplasts, mitochondria and peroxisomes, surface deformations of these organelles and formation of characteristic outgrowths and pocket concavities fi lled with cytoplasm with vesicles and organelles by chloroplasts. In reproduction biology of examined Caryophyllaceae and Poaceae plants growing in natural conditions, in the Arctic and in the Antarctic, and in a greenhouse in Olsztyn showed that this plant develops two types

Pharmacognostical studies on the endemic medicinal plant - Jatropha maheswarii Subr. & Nayar (Euphorbiaceae).

Abstract: Jatropha species are known for many biological activities like anticancer, hepatoprotective and pesticidal activity. Jatropha maheswarii Subr. & Nayar is an endemic medicinal taxon distributed in Southern east coast of Tamil Nadu, India. The stem and leaf of this plant are used by the rural folk similar to other Jatropha species in curing skin diseases, hemorrhage and tooth infections but it is unexplored. The present investigation intended to evaluate the pharmacognostical features of stem and leaf of this species. The pharmacognostical parameters were carried out by complete botanical evaluation which includes macroscopic, microscopic, physicochemical and phytochemical analysis. Pharmacognostical standard serve as an reference piece and helps in the further identification and authentication of this taxon.

Cytomorphology of Gentiana kurroo: an important endangered bitter plant of temperate Himalaya

Abstract: Gentiana kurroo, a potent bitter drug plant of Indian subcontinent, is under threat due to over exploitation and destruction of natural habitat. We studied the morphophenology and chromosomes of G. kurroo on both wild and field grown plants, which is very important for proper identification, conservation and domestication. Results reveal that G. kurroo is a perennial herb, and its shoot is represented by flowering branches only. Stem is modified to rhizome. The older rhizomes split into four parts at collar region appearing to fuse together at the ends and is an important diagnostic feature for crude raw materials. Two types of leaves i.e. radical leaves at the base of the plant and cauline leaves on flowering shoot are present. Flowering occurs during September to October with 1–9 inflorescences per plant. Inflorescence is terminal monocasial cysome type. Flowers are protrandus. Anthesis starts around 7.30 am and continued till 10.0 am. Ovary is bicarpillary syncarpous unilocular. Fruit is Capsule and takes 18–20 days to mature after fertilization. Seeds are very small elliptical and 1 000 seeds weigh to 0.1275 g. Chromosomal studies made by usual squash method reveals the species is a genomic allotetraploid with n = 13. The anaphase-I segregation was normal and in none of the cells at Anaphase-I or Telophase-I could any abnormality like laggards, bridges, micronuclei etc. be observed.

Correlation analysis of tuber yield and yield related characters in two cassava (Manihot esculenta Crantz ) morphological-types grown under nine weed management systems in the Guinea savanna zone of Nigeria

Abstract: Objective: The interplay of weed management options and temporal environment on correlative responses of two cassava morphotypes were studied with the aim of elucidating growth and yield correlation patterns under weed management and temporal environment. Methodology and results: The two cassava morphological types ‘NR 8082’ (short with profuse branching) and ‘TMS 30555’ (tall and non-branching) were subjected to nine different weed management options in a split plot design replicated three times. Data on weed biomass, cassava growth and yield parameters were subjected to multiple correlation analyses. Results revealed that weed dry matter had significant negative correlation with plant height (r = - 0.975**), plant girth (r = - 0.796**), tuber diameter (r = - 0.841**), tuber weight (r = - 0.929**), and average whole plant biomass yield (r = -0.921**) in 2008 cropping season for the branching cultivar. In 2009, a similar correlative response trend was also obtained, weed dry matter showed highly significant negative correlation with plant height (r = -0.984**), plant girth (r = -0.789**), tuber diameter (r = -0.822**), tuber weight (r = -0.911**), and average whole plant biomass yield (r = -0.901**). For the non-branching cultivar, weed dry matter also demonstrated strong and significant negative relationship with the following growth and yield parameters: plant height (r = --0.910**), plant girth (r = 0.763**), tuber diameter (r = -0.805**), tuber weight (r = -0.864**), and average whole plant biomass yield (r = -0.860**) in 2008. In 2009, the data revealed strong and significant negative relationship between weed dry matter and plant parameters as follows: plant height (r = --0.966**), plant girth (r = -0.772**), tuber diameter (r = -0.898**), tuber weight (r = -0.940**), and average whole plant biomass yield (r = -0.928**). Conclusion and application: Irrespective of cultivar or cropping year, plant height was significantly and positively correlated with average tuber weight and average whole total plant biomass yield (in most cases, with r-values > 0.90**). The correlative responses obtained for the two cultivars expectedly suggest that weed interference limits genetic productive potentials of the crop. The implication is that weed management strategies will indirectly enhance genetic expression of the cultivar thereby improving yield.

A single recessive gene conferring short leaves in romaine × Latin type lettuce (Lactuca sativa L.) crosses, and its effect on plant morphology and resistance to lettuce drop caused by Sclerotinia minor Jagger

Abstract: With 1 figure and 5 tables Abstract Understanding the relationship between plant morphology and disease resistance is crucial to successful lettuce breeding. Latin type cultivars are a potential useful source of resistance to Sclerotinia minor for breeding resistant romaine cultivars. However, resistance in Latin cultivars may be conditioned by their relatively short stature. The objective of this research was to determine the segregation for plant height and the relationship between plant height and S. minor resistance in romaine × Latin crosses. The frequency of short plants was conditioned by a single recessive gene in F1, F2 and F3 families from nine romaine × Latin crosses tested in 2007, 2008 and 2009 field experiments. The gene, named short leaf 1 (sl1), affects only leaf length in rosette plants and is morphologically distinct from other dwarfing genes. In two S. minor-infested field experiments with 75 F3 romaine × ‘Eruption’ families, no difference in disease incidence was detected between short (sl1sl1), tall (Sl1Sl1) or segregating families. Therefore, development of resistant romaine cultivars from crosses with ‘Eruption’ is feasible.

Morphology, Biomass, and Vessel Diameter of Pigeon Pea Subjected to Water Stress

Abstract: This research was designed to study the effects of drought on pigeon pea [Cajanus cajan (L.) Millsp.] morphology, biomass, and vessel diameter. Cultivated seeds of pigeon pea (cv. Georgia-II) were germinated, maintained in an environmental chamber, and arranged as a split-plot design with four replications; harvest was the main effect and watering regimens were tested against residual error. Plants were watered every 2, 4, 8, 16, or 32 days. Number of stems and leaves, as well as total plant height, were measured weekly. Dry weight (DW) of roots, stems, and leaves were recorded at each harvest, and root cross sections were viewed to determine vessel diameter. Results indicated that plant morphology, biomass, and vessel diameter were significantly affected by harvest and watering regimen. Plants watered more frequently had more stems and leaves, grew taller, accumulated greater DW, and had larger diameter vessels within root tissue.