Number Of Locules Research Articles

Diagnostic contributions of imaging features to differentiate ameloblastomas from keratocystic odontogenic tumours: a commentary

In reference to an article by Ariji et al,1 we would like to thank the authors for an informative study. This article was enlightening owing to the paucity of studies conducted regarding this subject. The authors took great efforts to examine the various imaging features that can be useful for qualitative differential diagnosis between ameloblastomas and keratocystic odontogenic tumours (KCOTs). However, we would like to highlight certain ambiguities in this article. First, in the methodology, all 60 observers enrolled in the study gave a diagnosis after observing the images via a website. The imaging features which helped them come to a diagnosis were not mentioned in the article. It could have added to the authenticity of the study if all 60 observers were given a set of instructions with criteria (imaging features) for evaluation of the images. We feel that it would have been better if all observers specialized in radiology were included in the study and an intraobserver analysis was carried out to remove any observational bias, as in the study by O Ferreira et al.2 Second, in the results it was stated in the article that number of locules was an important imaging feature contributing to correct imaging diagnosis. We fail to understand the basis of this as only 3 ameloblastomas were multilocular, while the other 17 lesions (including all 10 KCOTs) were unilocular. Further, whether all images were viewed by each observer is not clearly stated in the article. The authors have made a very laudable recommendation to use characteristic imaging features to differentiate between these two lesions that present clinical and radiographic similarities but require different treatments. They have also proposed CT as a valuable tool with the possibility of measuring the different density patterns of the lesions, which until today is a poorly investigated subject.

Pineal cysts in children

ObjectiveTo describe the prevalence and characteristics of pineal cysts found on MRI in children.MethodsThis is a retrospective monocentric study of all brain magnetic resonance imaging (MRI) examinations performed under the same technical conditions for checking the idiopathic nature of short stature (ISS group, n = 116) and for the investigation of central precocious puberty (CPP) over a 3-year period (n = 56). Dimensions, wall and septal thickness, number of locules, signal intensity, and the presence of a solid component were analysed. Ten of 19 cysts were re-evaluated (follow-up interval 4–28 months). The prevalence of the pineal cysts was compared between the two groups using χ2 and Fisher’s exact tests, and a significance threshold of p < 0.05.ResultsThe prevalence of cysts was comparable in the two groups, CPP (10.7%) and ISS (11.2%). Cyst characteristics were similar in the two groups and 74% had thin septations. None of the cysts changed on follow-up. None of the children with pineal cysts exhibited neurological signs.ConclusionBenign pineal cysts are a common finding in young children. High-resolution MRI demonstrates that these cysts are often septated. This pattern is a normal variant and does not require follow-up MR imaging or IV contrast media.

Increase in Tomato Locule Number Is Controlled by Two Single-Nucleotide Polymorphisms Located NearWUSCHEL

In tomato (Solanum lycopersicum) fruit, the number of locules (cavities containing seeds that are derived from carpels) varies from two to up to 10 or more. Locule number affects fruit shape and size and is controlled by several quantitative trait loci (QTLs). The large majority of the phenotypic variation is explained by two of these QTLs, fasciated (fas) and locule number (lc), that interact epistatically with one another. FAS has been cloned, and mutations in the gene are described as key factors leading to the increase in fruit size in modern varieties. Here, we report the map-based cloning of lc. The lc QTL includes a 1,600-bp region that is located 1,080 bp from the 3' end of WUSCHEL, which encodes a homeodomain protein that regulates stem cell fate in plants. The molecular evolution of lc showed a reduction of diversity in cultivated accessions with the exception of two single-nucleotide polymorphisms. These two single-nucleotide polymorphisms were shown to be responsible for the increase in locule number. An evolutionary model of locule number is proposed herein, suggesting that the fas mutation appeared after the mutation in the lc locus to confer the extreme high-locule-number phenotype.

Reproductive mechanisms and pollen characterization in some accessions of an underutilized legume: (Sphenostylis stenocarpa Hochst Ex. A. Rich) harms

Studies on flowering, pollen, pod and seed characters, germination rate and seed set percentage were carried out on twenty five accessions of African Yam Bean (AYB). Self compatibility tests confirmed all the accessions as obligate selfers, while the reciprocal crosses were not successful. Germination rate, percentage seed set and pollen fertility were observed to be high in the accessions. Correlation analysis among the reproductive traits revealed that pod length, pod width, number of locules per pod and number of seeds per pod contributed significantly to the percentage seed set in all the accessions. Pollen fertility and seed viability were also observed to be high in all the accessions except in TSs23 where low pollen fertility, low seed viability and low percentage seed set were recorded. All the accessions produced tricolporate pollen grains. Pollen size ranged from 66.15 μm in TSs40 to 82.75 μm in TSs119, pollen fertility ranged from 53.39% in TSs23 to 95.30% in TSs119, seed set ranged from 83.32% in TSs90, 89.21% in TSs23 and 95.72% in TSs3. The germination rate ranged from 59.68% in TSs23 to 99.03% in TSs22. The percentage moisture content ranged between 4.38% in TSs22 and 11.43% in TSs119. Key words: Pollen characters, seed set, germination rate, self compatibility.

Biometria de frutos e sementes e emergência de plântulas de duas espécies frutíferas do gênero Campomanesia

As espécies Campomanesia adamantium e Campomanesia pubescens são morfologicamente semelhantes, ocorrem em ambientes comuns do Bioma Cerrado, por isso são difíceis de serem separadas e identificadas. Os objetivos foram analisar dados biométricos de frutos e sementes de C. adamantium e de C. pubescens, além do processo de emergência das plântulas, para fins de comparações entre as espécies. Em novembro de 2007, de 50 frutos de cada espécie, foram realizadas medidas do comprimento transversal (mm) e longitudinal (mm) dos frutos e das sementes, massa da matéria fresca dos frutos (g), número de lóculos por fruto e número de lóculos com sementes. Para o teste de emergência, dois experimentos independentes, um para cada espécie, foram instalados em delineamento inteiramente casualizado, com seis métodos de beneficiamento dos frutos para remoção, secagem ou lavagem da mucilagem e quatro repetições com 40 sementes por parcela. Com frutos mais volumosos, com maior acúmulo de massa fresca e maior amplitude biométrica em relação aos de C. pubescens, C. adamantium apresenta potencial para seleção de materiais promissores para fins de melhoramento. A secagem à sombra por 24 horas das sementes com mucilagem reduz os percentuais de emergência e de plântulas normais, além da velocidade de emergência de plântulas de C. adamantium, embora este método seja indiferente para plântulas de C. pubescens. Sob as mesmas condições experimentais, plântulas de C. pubescens apresentam maior capacidade de emergência e de plântulas normais, além de maiores frequências diárias de plântulas emersas e redução dos tempos de emergência em relação às plântulas de C. adamantium.

Distribution ofSUN, OVATE, LC, andFASin the Tomato Germplasm and the Relationship to Fruit Shape Diversity

Phenotypic diversity within cultivated tomato (Solanum lycopersicum) is particularly evident for fruit shape and size. Four genes that control tomato fruit shape have been cloned. SUN and OVATE control elongated shape whereas FASCIATED (FAS) and LOCULE NUMBER (LC) control fruit locule number and flat shape. We investigated the distribution of the fruit shape alleles in the tomato germplasm and evaluated their contribution to morphology in a diverse collection of 368 predominantly tomato and tomato var. cerasiforme accessions. Fruits were visually classified into eight shape categories that were supported by objective measurements obtained from image analysis using the Tomato Analyzer software. The allele distribution of SUN, OVATE, LC, and FAS in all accessions was strongly associated with fruit shape classification. We also genotyped 116 representative accessions with additional 25 markers distributed evenly across the genome. Through a model-based clustering we demonstrated that shape categories, germplasm classes, and the shape genes were nonrandomly distributed among five genetic clusters (P < 0.001), implying that selection for fruit shape genes was critical to subpopulation differentiation within cultivated tomato. Our data suggested that the LC, FAS, and SUN mutations arose in the same ancestral population while the OVATE mutation arose in a separate lineage. Furthermore, LC, OVATE, and FAS mutations may have arisen prior to domestication or early during the selection of cultivated tomato whereas the SUN mutation appeared to be a postdomestication event arising in Europe.

Genetic basis of long shelf life and variability into Penjar tomato

Penjar tomato is a varietal type cultivated in northeast Spain that characteristically has a long shelf life, small fruit, and wide morphological variability among cultivars. To determine the genetic basis for the long shelf life in the Penjar varietal type and to describe the genetic background and agromorphologic characteristics of the group, we studied 27 Penjar accessions representative of the entire range of variation in traits related to agronomic behavior, fruit morphology, and sensory quality. We found that the long shelf life of Penjar (mean: 126.8 days) is due to the ripening mutant alcobaca (alc), and the molecular basis of this mutation is the replacement of thymine by adenine in position 317 of the coding sequence of the NAC.NOR gene; thus, alcobaca (alc) is an allele of non-ripening (nor). The amplified fragment length polymorphism (AFLP) study found 18.07% polymorphic loci within the Penjar varietal type, which is higher than usual in landraces. The variation in agronomic and morphologic traits between accessions was also very high; thus, the heterogeneity of the Penjar group probably results from the introduction of the allele alc in distinct landraces. Our results also show that in germplasm containing the alc mutation shelf life is negatively correlated with fruit size (weight, width, length, and number of locules); thus, the predominance of small fruit within the varietal type is probably the result of this trait being dragged along in the selection for long shelf life.

Imaging features contributing to the diagnosis of ameloblastomas and keratocystic odontogenic tumours: logistic regression analysis

The aim of this study was to clarify the characteristic imaging features that can be used to differentiate ameloblastomas from keratocystic odontogenic tumours and to examine the significant imaging features contributing to a correct diagnosis. 60 observers (39 specialists in oral and maxillofacial radiology and 21 non-specialists) examined CT and/or panoramic images of 10 ameloblastomas and 10 keratocystic odontogenic tumours shown on a webpage and made diagnoses. Their correct answer ratios were then calculated. The imaging features of the tumours were evaluated and expressed as binary numbers or quantitative values. The imaging features that contributed to a correct diagnosis were elucidated using logistic regression analysis. The mean correct answer ratio was 61.3% ± 17.2% for the diagnosis of ameloblastomas and keratocystic odontogenic tumours. CT images produced higher correct answer ratios for diagnosis of keratocystic odontogenic tumours by specialists. The significantly different imaging features between ameloblastomas and keratocystic odontogenic tumours were the degree of bone expansion and the presence of high-density areas. The significant imaging features contributing to a correct imaging diagnosis were the number of locules, the presence of high-density areas and the inclusion of impacted teeth. The presence of high-density areas is the most useful feature in the differential diagnosis of ameloblastomas and keratocystic odontogenic tumours based on comparison of the imaging features of both tumours and examination of the diagnostic contributions of these features.

Morphological intraspecific variabilities in African yam bean (AYB) (Sphenostylis stenocarpa Ex. A. Rich) Harms

Intraspecific variabilities in 25 IITA accessions of African yam bean (AYB) (Sphenostylis stenocarpa Ex. A. Rich.) Harms were assessed through characterization of 36 morphological characters. The intraspecific variabilities among the accessions were evaluated by the following statistical analysis tools: Analysis of Variance (ANOVA), principal component and cluster analysis (Semi – partial R-squared method). The accessions showed significant differences in a number of morphological characters and the P values indicated significant differences (p ≤ 0.0001) in 27 characters. Statistical analysis showed that terminal leaflet length, terminal leaflet width, peduncle length, pod length, pod width, number of locules per pod and number of seeds per pod contributed significantly to seed set percentages in all the studied populations. Cluster analysis on the morphological data clustered the accessions into six distinct groups with pod and seed traits contributing significantly to the grouping. Pod lengths, number of seeds per pod and seed weight were observed to be useful characters for genetic improvement of AYB. Key words: Morphological characterization, intraspecific variabilities, Sphenostylis stenocarpa, cluster groups.

Quantitative trait loci (QTL) analysis for antioxidant and agronomically important traits in tomato (Lycopersicon esculentum)

Tomato is one of the most widely produced and consumed vegetable crops worldwide. Plant breeders have usually focused on improvement of horticulturally important traits such as yield, fruit size, shape and colour. With increased attention on human health, however, plant breeders also consider the improvement of health-related traits of fruits and vegetables such as antioxidant characters. In the present study, genes controlling both health-related and horticulturally important traits were mapped in the tomato genome using 152 Lycopersicon hirsutum BC_2F_2 individuals. For this aim, all plants were phenotypically and genotypically characterised and a total of 75 QTLs were identified for all traits. Of the 75 QTLs, 28 were identified for 5 antioxidant traits including total water soluble antioxidant capacity, vitamin C, total phenolics, total flavonoids, and lycopene contents, and 47 QTLs were identified for 8 agronomic traits including fruit weight, external and internal fruit colour, fruit firmness, fruit shape, stem scar size, locule number, and wall thickness. Markers linked with these QTLs can be used in marker assisted selection (MAS) for improvement of elite tomato lines.

Physical and mechanical properties of tomato fruits as related to robot’s harvesting

In order to better design, fabricate and control tomato harvesting robot, selected physical properties such as height, diameter, sphericity, surface area, volume, total mass, mass of pericarp and gelatinous matter, bulk density, density of pericarp and gelatinous matter, porosity, projected area, shape factor, and radius of curvature of two cultivar tomato fruits with different locule numbers were mainly investigated by image analysis and water displacement method. Mechanical properties such as friction and rolling resistance coefficients, and rupture energy, rupture force, compressibility, and loading slope of tomato fruits at two loading positions were determined by pull and loading test. Results showed the locule number had a significant effect ( P < 0.05) on certain physical and mechanical parameters, such as height, diameter, surface area, rupture force, compressibility, and friction coefficient. The loading position also showed a significant effect ( P < 0.05) on certain mechanical parameters, such as compressibility. The obtained properties are closely related to robot’s harvesting.

Fruits of Cornelian Cherries (Cornaceae: Cornus subg. Cornus) in the Paleocene and Eocene of the Northern Hemisphere

Fossil fruits confirm that cornelian cherries (Cornus, subgenus Cornus) were established in the Northern Hemisphere in the Early Tertiary. We describe the oldest known member of the subgenus, Cornus piggae sp. n., on the basis of well‐preserved silicified endocarps from the late Paleocene of North Dakota. The endocarps are ellipsoidal, thin walled, and two to three locular, and they lack an axial longitudinal bundle. The septa and external walls of the fruit stone are riddled with cavities, a feature diagnostic of extant subgenus Cornus. For comparison, we sectioned fruits of each of the extant species and reexamined fossil fruits from the Early Eocene London Clay of southern England. These London Clay fossils differ from C. piggae by much thicker external walls (Cornus ettingshausenii [Gardner] Eyde) and higher locule number (up to 6 in Cornus multilocularis [Gardner] Eyde). Comparison with fruits of extant cornelian cherries indicates that the morphological range among the modern species is narrower than that seen in the Paleogene.

Uso do algoritmo de Gower na determinação da divergência genética entre acessos de tomateiro do grupo cereja

Using Gower's algorithm on the genetic divergence determination among cherry tomato accessions. The joint analysis of qualitative and quantitative variables has been considered a useful tool to estimate the genetic divergence among accessions of a gene bank. The purpose of this research was: (i) to characterize a collection of cherry tomatoes, using quantitative and qualitative descriptors, and (ii) to use Gower's algorithm to quantify genetic divergence among genotypes, employing a joint descriptors analysis. Forty accessions of organically grown cherry tomato were studied in Seropedica, Rio de Janeiro, Brazil. Four qualitative fruit descriptors and nine qualitative descriptors were used. Data were analyzed using Gower's algorithm. There was variability for color, shape and number of locules per fruit. The red color was observed in fruits of 25 accessions. Fruit with different colors such as yellow, orange and brown were also observed. Regarding locule number, the presence of fruit with two, three, four and even with seven locules was detected. The UPGMA method resulted in the highest value for cophenetic correlation (0.80) and seven clusters were formed. The formed clusters made it possible to distinguish fruit classified as cherry tomato from other type grouped in different clusters, because the fruits this category were larger than cherry type considering the equatorial diameter of the fruit.

MEAN PERFORMANCE , HETEROSIS AND COMBINING ABILITIES OF TOMATO CROSSES UNDER SALINE CONDITIONS

Field trials were carried out at the Experimental Research Station of Desert Research Center at Ras Sudr , South Sinai Governorate during 2003 and 2004 seasons . This investigation aimed to improve tomato genotypes for salinity tolerance in SuperMarmand and CastleRock and marketable characters in exotic genotypes LA1673 and LA1963 and Edkawy the results indicated that Edkawy genotypes was superior than the other tomato genotypes in plant height, number of fruits/ plant, number of locules / fruit and total soluble solids in fruit under saline condition. While, the two local genotypes of tomato SuperMarmand and Castle Rock were earlier and heavier than the other studied genotypes in early yield, average weight / fruit and total yield / plant . The crosses Edkawy × LA 1673 , SuperMarmand × LA 1963 and LA 1673 × LA 1963 recorded positive and significantly heterosis for average fruit weight . Both additive and non-additive gene actions were involved in the genetic control of each plant height, number of fruits/ plant, early yield , number of locules/ fruit, average fruit weight , total soluble of solids ( TSS ) and total yield/plant. Non-additive gene effects were more important than additive ones for all studied characters except average fruit weight and total yield/ plant, where additive gene effect was more important in the inheritance of both characters . Heritability in broad sense for all the studied characters were high and ranged from (64.55%) for total soluble of sugar in fruit to (88.4%) for average of fruit weight. Whereas, heritability in narrow sense was moderate (39.51%) for total soluble of solids (TSS) and high ( < 50 % ) for the remaining characters under study . Positive and highly significant GCA effects were recorded for plant height and number of locules / plant in Edkawy and LA1673 ; number of fruits / plant , early yield and TSS in Edkawy and castle Rock as well as average fruit weight and total yield / plant in castle Rock and SuperMarmand. The cross Castle Rock × LA 1963 was the heaviest average fruit weight and the followed that cross Edkawy × LA 1673 and Edkawy × Castle Rock were positive and significantly SCA effects. While, the crosses SuperMarMand with each of LA 1673 and LA1963 respectively were positive and significantly SCA effects for total soluble of sugar (TSS). The crosses Castle Rock × SuperMarmand and Castle Rock × LA 1673 were the heaviest grain yield/ plant and highly significant positive for combing ability SCA effect under saline condition in irrigation water at Ras Sudr region.

Análise de trilha de componentes de produção primários e secundários em tomateiro do grupo Salada

O objetivo deste trabalho foi avaliar as correlações genotípicas e seus desdobramentos em efeitos diretos e indiretos de componentes de produção primários e secundários sobre a produtividade de frutos em acessos de tomateiro, pela análise de trilha. Foram utilizados dados de 20 características, avaliadas em 132 acessos de tomateiro do grupo Salada, do Banco de Germoplasma de Hortaliças da Universidade Federal de Viçosa. Após o diagnóstico de multicolinearidade, oito características foram descartadas, e a análise de trilha foi realizada com: variável principal (produção total de frutos); variáveis primárias (peso médio e número total de frutos); e variáveis secundárias (frutos não comercializáveis, índice de precocidade, comprimento da folha, espessura do pecíolo principal, comprimento e diâmetro do entrenó, número de lóculos, acidez total e sólidos solúveis totais dos frutos). O comprimento da folha, o índice de precocidade e o diâmetro do entrenó apresentaram maior correlação genotípica com a produção total de frutos (0,69; -0,54 e 0,5, respectivamente). A análise de trilha com um único diagrama causal mostrou igual importância das variáveis primárias na determinação da produção. A análise de trilha com dois diagramas causais mostrou que a seleção simultânea do comprimento da folha e do diâmetro do entrenó pode ser uma boa alternativa para a obtenção de ganhos na produção total de frutos.

Tomato (L. esculentum Mill.) Genotypes variability of fruit traits

Tomato (Lycopersicum esculentum Mill.) is vegetable which could be produced and consumed in a many different ways, due to its variability, made by breeding programs. Variability of analyzed genotypes was determinated for further fruit traits: average mass, fruit shape, locules number and dry matter content. Variability source structure was determinated using principal components analysis (PCA). Three main components, which explain 94,2 % of total variability, were chosen for further analysis. The biggest part of the first main component has fruit shape and locule number. The second component is determinated by dry matter content, and the third by the fruit mass. For more precisely perception of homology and divergence between analyzed genotypes, nonhierarchical grouping analysis (k-means) was performed, and genotypes were divided into three groups. Divergency was determinated for fruit mass and locule number, while for index shape and dry matter contetent analyzed genotypes are homologous. The aim of this study is to examine tomato genotypes variability for fruit traits.

Studies on Heterosis in Abelmoschus esculentus (L.) Moench and A. callei (A. Chev) Stevels Cultivars During Shorter Day Photoperiods in South Eastern Nigeria

Better parent heterosis was studied in direct and reciprocal crosses using 9 early and late okra cultivars which belonged to the Early-early, Early-late, Late-early and Late-late okra flowering types. The ANOVA for length of pod, circumference of pod, number of locules per pod, number of seeds per pod, Number of pods per plant, weight of 1000 seeds, density of seeds, weight of pods per plant, days to flower opening, plant height and circumference of stem at 10 cm above soil level, showed almost very highly significant differences-an indication that the cultivars are genetically diverse. Very highly significant, narrow and intermediate, heterosis was recorded for most of the direct and reciprocal crosses, showing that selections could be made from the hybrids to meet desired local okra qualities. A cross between an Early-late and Late-early parents, using early okra as the maternal parent, gave rise to a stable viable bridge hybrid which outperformed the better parent in many respects thereby overcoming the hitherto strong barrier to gene flow in interspecific hybridization studies involving the two okra types and also indicating the existence of maternal effects. Consequently with this development, the window has been opened for possible accelerated transfer of several desirable genes from late okra types to many promising but vulnerable early okra types. This could result to minimizing the further erosion of such early okra germplasm still in the custody of the local farmers.

Desempenho e qualidade de frutos de tomateiro em cultivo protegido com diferentes números de hastes

Com o objetivo de avaliar diferentes orientações de crescimento, em tomateiro cultivado sob ambiente protegido, e seus efeitos sobre a produtividade e qualidade, foi conduzido um experimento em casa de vegetação, em solo preparado de acordo com as recomendações técnicas para a cultura. Adotou-se o espaçamento de 1,0 m entre linhas por 0,5 m entre covas. Foi utilizado o delineamento em blocos casualizados com 8 tratamentos e 4 repetições, em esquema fatorial 2x2x2, sendo dois sistemas de condução (deixando-se apenas uma haste por planta e deixando-se duas hastes por planta); dois sistemas de desbrota (convencional e diferenciada); dois números de plantas por cova (uma e duas plantas por cova). Cada parcela foi constituída de sete plantas, sendo avaliadas as cinco plantas centrais de cada parcela. Na desbrota convencional todos os brotos laterais foram retirados e, na desbrota diferenciada foram deixados os brotos laterais, e nestes um rácemo. Foram avaliados o número de rácemos por planta, altura do primeiro rácemo, número de frutos por planta, diâmetro e comprimento dos frutos, espessura da polpa, massa dos frutos, número de lóculos por fruto, diâmetro do lóculo, produção estimada total e comercial, pH, acidez titulável, sólidos solúveis e vitamina C. Para as condições em que o trabalho foi conduzido e com base nos resultados obtidos recomenda-se a condução de duas plantas por cova, duas hastes por planta e desbrota do tipo convencional.

COMBINING ABILITY AND HETEROSIS FOR FRUIT YIELD AND QUALITY IN MANZANO HOT PEPPER (Capsicum pubescens R &amp; P) LANDRACES

Hybridization as a method for plant breeding may create improved varieties with higher fruit yield and quality by taking advantage of the combining ability and heterosis between the crossed parents. Six landrace varieties (five collected in Mexico and one in Peru) of manzano hot pepper (Capsicum pubescens R & P) and all their possible direct single crosses were evaluated, for heterosis and general and specific combining abilities (GCA and SCA) for fruit yield and quality. Plants were grown under greenhouse conditions and drip irrigated with a complete nutrient solution. Analyses for GCA, SCA and heterosis were based on the Griffing’s fixed model of diallel design method II, and on analysis II of Gardner and Eberhart. Significant GCA effects were found for fruit yield, fruit volume, pericarp thickness, seed number and weight per fruit, and on locule number per fruit. The highest GCA values were registered in landrace ‘Puebla’. The highest heterosis relative to the best parent was found in the cross ‘Zongolica x Puebla’ for fruit yield (51 %), in ‘Peru x Chiapas’ for fruit volume (33 %), in ‘Puebla x Peru’ for seed number (22 %), and in ‘Puebla x Chiapas’ for seed weight (38 %) and locule number (18 %). These hybrids also showed high SCA values. ‘Puebla’ was the best landrace as a parent in hybrids. It had the highest frequency of high yielding hybrids with high fruit volume and pericarp thickness, compared with the other five landraces. Thus, hybridization can be a useful method for breeding manzano hot pepper to exploit combining abilities and heterosis.

Diallel analysis involving heat-tolerant lines of tomato.

The critical factor in setting of tomato fruits is night time temperature, the optimum range being 15- 21°C. Fruit set in tomato is reduced markedly when average maximum day time and minimum night time tem- peratures go above 32 and 21°C, respectively. In the northwestern plains of India, temperature crosses the favor- able limit from the fourth week of April onwards, thereby reducing yield, lowering quality and shortening the fruit harvest span. The situation has forced tomato breeders to develop heat-tolerant cultivars and, therefore, the present study was conducted to determine the nature of gene action controlling various characters and to iden- tify a few good combiner genotypes that may be used in further breeding programmes for high temperature tol- erance. Highly significant general combining ability (gca) and specific combining ability (sea) variances indicat- ed the importance of both additive and non-additive gene action in the expression of all the characters. Howev- er, the ratio of components of genetic variance revealed the predominant role of non-additive gene actions in con- trolling total yield, marketable yield, number of fruits per plant, average fruit weight, days from fruit setting to turning stage, endosperm utilization efficiency, harvesting span, pericarp thickness, number of locules, lycopene content and titratable acidity. Therefore, heterosis breeding may be used to bring improvement in these traits. However, additive gene action played a major role in controlling days to anthesis, number of flowers per cluster and setting percentage per cluster. Hence, lines having good gca for these traits (LST-6, LCT-9, LST-42-1 and LST-65-2) may be hybridized and selection may be practiced in segregating generations to develop advanced gen- eration lines having high heat-tolerance ability.