Diversity and variability in seed characters and growth of Pongamia pinnata (L.) Pierre accessions

A thorough and extensive wild germplasm exploration survey was undertaken and 50 high yielding candidate plus trees (CPTs) of Pongamia pinnata (L.) Pierre from different locations from a latitudinal and longitudinal spread between 12°41′ and 22°E longitude and 77° and 84°40′N latitude covering 11 locations in an area spread of 150,000 km² were collected for evaluating genetic association and variability in seed and growth characters. There were significant differences observed in seed morphology and oil content as was in plant height, and number of branches in the progeny trial. Plant height and number of branches exhibited much higher values of both phenotypic and genotypic variance than observed in the seed characters. Among seed characters oil content exhibited highest broad sense heritability of more than 93% followed by seed length (90.0%). In contrast seed width showed the second highest genetic advance of 5.64% following the highest genetic advance of 10.15% exhibited by oil content. Hierarchical clustering by Ward’s Minimum Variance Cluster Analysis method showed phylogeographic patterns of genetic diversity. K means clustering revealed that trees from different geographic regions were grouped together in a cluster and as were trees from the same geographical area placed in different clusters suggesting that geographical diversity did not go hand in hand with genetic diversity. In addition clustering identified promising accessions with favourable traits for future establishment of orchards.     

红松优树半同胞子代家系生长、结实及抗病虫能力的变异特征

以吉林省露水河宏伟种子园的551个优株29年生红松半同胞子代家系为材料,对其生长性状(树高、胸径、冠幅)、结实性状(连续7个结实年份的球果总数)和抗病虫能力进行调查,利用多性状综合评价的方法,结合生长、结实和抗病虫能力等6个性状,优选出优良家系和单株.结果表明: 各性状在不同家系间和区组间的差异均达到极显著水平;各性状的表型变异系数变化范围为13.9%～61.0%,极显著的差异与高的变异系数有利于优良家系的评价和选择;材积、结实量和抗病虫能力的家系遗传力(分别为0.47、0.52和0.48)均大于单株遗传力(分别为0.37、0.07和0.10);红松家系生长性状、结实性状和抗病虫能力之间呈极显著正相关关系.以5%的入选率初步选出28个优良家系,其材积、结实量和抗病虫能力的遗传增益分别为16.8%、71.4%和0.5%;以2%的入选率在优良家系中初步选出7个优良单株,其材积、结实量和抗病虫能力的遗传增益分别为66.8%、80.9%和0.7%.这些初选的优良家系和单株表现出明显优势,可指导无性系种子园去劣疏伐,并为高世代种子园的营建提供繁殖材料.     

Inheritance of quantitative traits in crosses between two <Emphasis Type="Italic">Pisum sativum</Emphasis> subspecies with particular reference to their breeding value

The experimental study was conducted during the period of 2008–2010 at the experimental field of the Institute of Forage Crops in Pleven. The hybridization scheme included direct and back crosses covering four varieties of forage pea (Pisum sativum L.), namely two spring ones, Usatii 90 and Kamerton from Ukraine, and a winter one from Bulgaria, Pleven 10. There was analyzed the inheritance of quantitative traits such as plant height, height to first pod, pod number per plant, seed number per plant, seed number per pod, seed weight per plant and number of fertile nodes per plant of parental components (P₁ and P₂) and both first (F₁) and second (F₂) hybrid generations. The cross Usatii 90 × Pleven 10 showed the highest real heterosis effect for plant height (8.26%), pods per plant (158.79%), seeds per plant (272.16%), seeds per pod (42.09%), seed weight per plant (432.43%) and number of fertile nodes per plant (117.14%). The cross Pleven 10 × Usatii 90 had the highest real heterosis effect height to first pod (11.06%). In F₂ plants, the strongest depression for plant height (5.88%), seeds per plant (57.88%), seeds per pod (55.93%) and seed weight per plant (55.99%) was in the cross Usatii 90 × Pleven 10, for height to first pod (1.47%) in the cross Kamerton × Pleven 10 and for number of fertile nodes per plant (15.91%) in the cross Pleven 10 × Usatii 90. The highest positive degree of transgression for number of fertile nodes per plant (165.64%) and seed weight per plant (162.10%) was in the cross Pleven 10 × Kamerton and for pod number per plant (102.54%) and seeds per plant (99.13%) in Kamerton × Pleven 10. The stability of the characters was determined. Low variability in F₁ and F₂ was found in plant height (3.97–6.85%). Variability of number seeds per plant in F₁ was highest (11.86–33.23%). For all other traits, the variability varied from average to high. A lower narrow-sense heritability coefficient was observed for plant height, height to first pod, pods per plant, seeds per plant and seed weight per plant (from 0.001 to 0.230). In few cases, such as in fertile nodes per plant (0.39 and 0.81) and seeds per pod (0.44), the coefficients of broad-sense heritability were higher.     

Genetic analyses of agronomic and seed quality traits of synthetic oilseedBrassica napus produced from interspecific hybridization ofB. campestris andB. oleracea

The heritability, the number of segregating genes and the type of gene interaction of nine agronomic traits were analysed based on F₂ populations of synthetic oilseedBrassica napus produced from interspecific hybridization ofB. campestris andB. oleracea through ovary culture. The nine traits—plant height, stem width, number of branches, length of main raceme, number of pods per plant, number of seeds per pod, length of pod, seed weight per plant and 1000-seed weight—had heritabilities of 0.927, 0.215, 0.172, 0.381, 0.360, 0.972, 0.952, 0.516 and 0.987 respectively, while the mean numbers of controlling genes for these characters were 7.4, 10.4, 9.9, 12.9, 11.5, 21.7, 20.5, 19.8 and 6.4 respectively. According to estimated coefficients of skewness and kurtosis of the traits tested, no significant gene interaction was found for plant height, stem width, number of branches, length of main raceme, number of seeds per pod and 1000-seed weight. Seed yield per plant is an important target for oilseed production. In partial correlation analysis, number of pods per plant, number of seeds per pod and 1000-seed weight were positively correlated with seed yield per plant. On the other hand, length of pod was negatively correlated (r = -0.69) with seed yield per plant. Other agronomic characters had no significant correlation to seed yield per plant. In this experiment, the linear regressions of seed yield per plant and other agronomic traits were also analysed. The linear regression equation wasy = 0.074x₈ + 1.819x₉ + 6.72x₁₂ -60.78 (R ² = 0.993), wherex ₈, x₉ and x₁₂ represent number of pods per plant, number of seeds per pod and 1000-seed weight respectively. The experiment also showed that erucic acid and oil contents of seeds from F₂ plants were lower than those of their maternal parents. However, glucosinolate content was higher than that of the maternal plants. As for protein content, similar results were found in the F₂ plants and their maternal parents. It was shown that the four quality traits, i.e. erucic acid, glucosinolate, oil content, and protein content, had heritability values of 0.614, 0.405, 0.153 and 0.680 respectively.     

Application of self-organizing neural networks to classification of plant communities in Pangquangou Nature Reserve, North China

Vegetation classification is an important topic in plant ecology and many quantitative techniques for classification have been developed in the field. The artificial neural network is a comparatively new tool for data analysis. The self-organizing feature map (SOFM) is powerful tool for clustering analysis. SOFM has been applied to many research fields and it was applied to the classification of plant communities in the Pangquangou Nature Reserve in the present work. Pangquangou Nature Reserve, located at 37°20′–38°20′ N, 110°18′–111°18′ E, is a part of the Luliang Mountain range. Eighty-nine samples (quadrats) of 10m × 10m for forest, 4m × 4 m for shrubland and 1m × 1m for grassland along an elevation gradient, were set up and species data was recorded in each sample. After discussion of the mathematical algorism, clustering technique and the procedure of SOFM, the classification was carried out by using NNTool box in MATLAB (6.5). As a result, the 89 samples were clustered into 13 groups representing 13 types of plant communities. The characteristics of each community were described. The result of SOFM classification was identical to the result of fuzzy c-mean clustering and consistent with the distribution patterns of vegetation in the study area and shows significant ecological meanings. This suggests that SOFM may clearly describe the ecological relationships between plant communities and it is a very effective quantitative technique in plant ecology research. __________ Translated from Acta Ecologica Sinica, 2007, 27(3): 1005–1010 [译自: 生态学报]     

Genetic diversity in a seed production population vs. natural populations of Sitka Spruce

Isozyme analysis was applied to estimate the level of variation and the genetic structure of a seed-production population (i.e., seed orchard) and 10 range-wide natural populations of Sitka spruce (Picea sitchensis (Bong.) Carr.). Gene diversity and heterozygosity estimates were comparatively high in both the seed orchard and the natural populations studied. The seed orchard population showed a significantly higher number of alleles per locus and percentage of polymorphic loci. Though not significant, mean heterozygosity of the seed orchard was higher than that observed for all natural populations. Genetic distance analysis indicated that the seed-orchard population was genetically similar to three natural populations from which the parent trees were selected. Parent trees sampling breadth has been identified as the major cause for the observed increased level. The impact of recurrent selection and seed orchard biology and management on maintaining the genetic diversity is discussed.     

Relationships between Population Size, Genetic Diversity and Fitness Components in the Rare Plant Dictamnus albus in Central Germany

An increasing number of studies support the hypothesis that smaller populations face a higher risk of extinction, and declining population sizes are therefore one of the focal points in plant conservation. In small populations, loss of genetic diversity is often related to reduced reproductive fitness. For the rare Dictamnus albus in Central Germany, an earlier study had already confirmed a significant correlation between population size and genetic diversity. In order to assess whether these variables correlate with fitness components, plant height; flower, fruit and seed production; and germination were studied in a total of 11 populations of different size. In the seven populations that were sampled over two consecutive years, differences among populations and among years were tested using a Two-Way ANOVA. Co-linearity among variables was assessed using principal component analysis (PCA), followed by calculating correlations between ordination axes and both population size and genetic diversity. Plant height and flower number were uncorrelated to the other variables and, together with germination, did not show any correlation to either population size or genetic diversity. However, both size and genetic diversity of populations correlated significantly with other PCA axes that reflected reproductive components such as fruit number, seed number, seed fruit ratio, and seed mass. Our results support the idea that reproduction is hampered in small populations and raise concerns over the loss of genetic diversity in D. albus.     

Variation of lignans in Norway spruce (Picea abies [L.] Karst.) knotwood: within-stem variation and the effect of fertilisation at two experimental sites in Finland

Lignan concentrations in Norway spruce (Picea abies [L.] Karst.) knotwood were studied in two long-term nitrogen fertilised experimental sites: a boreal site (66°5′N, 27°07′E) close to the Arctic tree line in northern Finland and a boreal site (61°10′N, 26°03′E) in southern Finland. Altogether 20 mature trees, representing five different size classes, were felled in the autumn 2002 and knots of the largest and smallest diameter in each whorl at the height of 4 m were analysed. Within-stem variation of knotwood lignans was studied at the 4 m intervals from stump height to the top from five control trees in the southern site. The following knotwood lignans were identified with GC-MS: hydroxymatairesinol (two isomers), secoisolariciresinol, α-conidendrin, α-conidendric acid, isohydroxymatairesinol, lariciresinol, lignan A, matairesinol, nortrachelogenin, todolactol A and isoliovil. The predominant lignan in Norway spruce knotwood was hydroxymatairesinol comprising approximately 77% of the total concentration of lignans. In mature trees in the southern site, the lignan concentrations were highest close to the starting point of the living branches. In the northern site, the total concentration of knotwood lignans was significantly higher (approximately 14% of the dry mass) than in the southern site (approximately 5.4% of the dry mass). In the northern site in control trees, a negative linear correlation was detected between branch diameter and hydroxymatairesinol concentration, but the similar correlation was not detected in fertilised trees or in the trees of the southern site. The possible reasons for higher hydroxymatairesinol concentrations in the northern knots were discussed.     

Genetic control of flowering time in Eucalyptus globulus ssp. globulus

Understanding the factors affecting variation in phenology within a species is important as flowering time constitutes one of the major barriers to gene flow. We studied the genetic and environmental control of flower initiation and anthesis time in E. globulus ssp. globulus. For 5 years, flower initiation and anthesis were monitored in a seed orchard containing clones of 63 genotypes from four different regions of the species’ natural distribution. Anthesis occurred over a long period each year, spanning as much as 9 months in 2008. This variation was under strong genetic control with little genotype by year interaction (broad-sense heritability, Ĥ ² = 0.78 ± 0.04). There were highly significant differences among regions; anthesis occurred earlier for Furneaux and Tasmania than Strzelecki and Otways each year. Surprisingly though, there was little variation in flower initiation time between regions and genotypes, and this was under weak genetic control (Ĥ ² = 0.06 ± 0.05). The average anthesis time in the orchard varied from year to year, and there was evidence that heat sum was a major driver of this environmental variation. Anthesis time is controlled by both genetic and environmental factors, with the responses to each being predictable to some extent, and unrelated to the timing of flower initiation.     

Levels of genetic diversity at different stages of the domestication cycle of interior spruce in British Columbia

Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia “interior” spruce (Picea glauca×engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone’s seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci while the expected hetrozygosity (0.207 vs 0.210) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations’ rare alleles were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen contamination in the orchard. It is suspected that the reduction in the plantation was caused by an unintentional selection in the nursery. Simulated roguing in the orchard did not drastically reduce even if up to 50% of the orchard’s clones were rogued. However, roguing was associated with a reduction in the average number of alleles per locus (i.e., sampling effect). Received: 2 January 1996 / Accepted: 24 May 1996     

Effect of Mechanical Stress on Cotton Growth and Development

Agricultural crops experience diverse mechanical stimuli, which may affect their growth and development. This study was conducted to investigate the effects of mechanical stresses caused by hanging labels from the flower petioles (HLFP) on plant shape and cotton yields in four cotton varieties: CCRI 41, DP 99B, CCRC 21, and BAI 1. HLFP significantly reduced plant height by between 7.8% and 36.5% in all four lines and also significantly reduced the number of fruiting positions per plant in the CCRI 41, DP 99B and CCRC 21 lines. However, the number of fruiting positions in BAI 1 was unaffected. HLFP also significantly reduced the boll weight for all four cultivars and the seed cotton yields for CCRI 41, DP 99B and BAI 1. Conversely, it significantly increased the seed cotton yield for CCRC 21 by 11.2%. HLFP treatment did not significantly affect the boll count in the fruiting branches of the 1^st and 2^nd layers in any variety, but did significantly reduce those on the 3^rd and 4^th fruiting branch layers for CCRI 41 and DP 99B. Similar trends were observed for the number of bolls per FP. In general, HLFP reduced plant height and boll weight. However, the lines responded differently to HLFP treatment in terms of their total numbers of fruiting positions, boll numbers, seed cotton yields, etc. Our results also suggested that HFLP responses might be delayed for some agronomy traits of some cotton genotypes, and that hanging labels from early-opening flowers might influence the properties related with those that opened later on.     

Diversity of Breadfruit (<Emphasis Type="Italic">Artocarpus altilis</Emphasis>, Moraceae) Seasonality: A Resource for Year-Round Nutrition<Superscript>1</Superscript>

Diversity of Breadfruit ( Artocarpus altilis , Moraceae) Seasonality: A Resource for Year-Round Nutrition. Breadfruit, Artocarpus altilis (Parkinson) Fosberg, is an important but underutilized staple crop cultivated throughout Oceania and much of the wet tropics. Indigenous peoples have selected and cultivated cultivars with different fruiting seasons to effectively extend fruit production for most of the year. In the present study, the seasonality of 219 breadfruit accessions originating from 17 Pacific island groups, the Seychelles, the Philippines, and Indonesia, and now growing in the National Tropical Botanical Garden’s (NTBG) Kahanu Garden, Hana, Hawaii, were evaluated. The predominant season of male flower production for most cultivars was from May to September, and fruit was produced most frequently between August and January. However, there were differences in the duration of the fruiting season from year to year and among cultivars. Over the 10-year period, 14 cultivars did not reliably produce fruit; most of this group were ‘ulu afa’ trees collected from Tokelau. About 24 cultivars exhibited very little seasonality and produced fruit throughout the year. The rest of the cultivars could be clustered into seasonality groups with characteristic fruiting patterns. Comparison of literature values indicates that unlike Hawaii, the breadfruit season in most locations begins around the date the sun reaches zenith prior to the summer months and extends throughout the summer months. Five cultivars asexually propagated from the NTBG collection growing in Kiribati (1°28′ N) exhibit similar fruiting patterns as in Hawaii, except that they begin 2–3 months earlier. These data predict that cultivars with complementary fruiting seasons in Hawaii may experience a temporal shift in their seasonality but will maintain their compatibility when cultivated in different locations and could enable year-round fruit production in many regions.     

Estimates of broad-sense heritability for seed yield and yield criteria in faba bean (Vicia faba L.)

Eight faba bean (Vicia faba L.) genotypes were grown at lowlands of the west-Mediterranean region of Turkey in order to estimate the broad-sense heritability for plant height, number of stems and pods per plant, seed yield, biological yield, 100-seed weight, days to flowering and maturity. The heritability for plant height, number of stems and pods per plant, seed yield, biological yield, 100-seed weight, days to flowering and maturity were estimated as 83%, 63%, 43%, 62%, 52%, 99%, 97% and 97%, respectively. It was found that seed weight was the least affected trait across changing environmental conditions and followed by days to flowering and maturity. On the other hand, number of pods per plant, biological and seed yields and number of stems per plant were the most affected traits versus environmental conditions.     

A comparison of the effect of genetic improvement, seed source and seedling seed orchard variables on progeny growth in Eucalyptus nitens in South Africa

Eucalyptus nitens is an important forestry species grown for pulp and paper production in the temperate, summer-rainfall regions of South Africa. A tree improvement programme has been ongoing at the Institute for Commercial Forestry Research for two decades, but genetic improvement in the species has been slow due to delayed and infrequent flowering and seed production. Three trials were established, firstly, to quantify the gains that have been made in the first generation of improvement in the breeding programme and, secondly, to establish whether a number of seed source and orchard variables influence the performance of the progeny. These variables were the amount of flowering trees in the seed orchard, year of seed collection, seed orchard origin and composition of seed orchard bulks. Diameter at breast height and tree heights were measured in the trials at between 87 and 97 months after establishment, and timber volumes and survival were calculated. Improved seed orchard bulks performed significantly better (p?<?0.01) than unimproved controls in the field trials. Genetic gains ranging from 23.2 to 164.8 m³?ha^?1 were observed over the unimproved commercial seed. There were significant differences (p?<?0.01) in progeny growth between the levels of seed orchard flowering, with higher levels of flowering (≥40 %) producing substantially greater progeny growth than lower flowering levels (≤20 %). The seed orchard had no effect on progeny growth in this trial series. This suggests that seed collected from any of the four seed orchards tested will produce trees with significant improvement in growth.     

The ecology and genetics of fitness in forest plants. IV. Quantitative genetics of fitness components in Impatiens pallida (Balsaminaceae)

Genetic and environmental variances were estimated for a number of characters in the annual plant Impatiens pallida by planting seed obtained through controlled crosses into their native field site or pots maintained in the greenhouse. Significant additive genetic variance was detected for three of 11 characters studied—germination date, cotyledon area, and date of first flower production. Significant dominance and/or maternal variance was found for seed weight, proportion of seeds germinating, cotyledon area, plant height, and number of leaves produced. Environmental variance was greater in the field compared with the greenhouse. Characters found to be under strong directional selection in a previous study showed no detectable additive genetic variance. While these populations exhibit conditions that in theory could contribute to the maintenance of genetic variation (limited pollen and seed dispersal distances and small-scale variation for edaphic characteristics influencing plant growth), levels of additive genetic variance for most characters were not significantly different from zero.     

Divergent seed production responses of white and blue flowers of Gentiana leucomelaena (Gentianaceae) to warming and watering

Background: The adaptation, evolution and function of flower colour diversity in response to changing environments are one of the oldest puzzles in plant ecology. It is logical that comparative studies on fitness of flower colour would be the most meaningful if they were conducted on the same genotype.

Aims: We used Gentiana leucomelaena, which produces both white and blue flowers on different tillers of the same individual, as a model species to test adaption and fitness differences of contrasting flowers in contrasting environments.

Methods: We examined seed production by white and blue flowers in response to increased temperatures (28 °C/2 °C vs. 12 °C/2 °C; 12 h light/12 h dark) in a climate chamber study and to watering in the field (+1.5 l m^?2 d^?1 vs. control with no supplementary irrigation).

Results: For white and blue flowers warming decreased but watering increased seed number. Increased temperature and watering increased the size of seeds from white flowers, but neither warming nor watering significantly changed seed size of blue flowers. Seed size was significantly negatively correlated with seed number in the temperature treatments but positively correlated in watering treatments. The positive correlation was strong in white flowers, but the negative correlation was stronger in blue than in white flowers.

Conclusions: Water availability and low temperature confer an advantage to white flowers, while warming and dry habitats favour blue flowers. These divergent responses may influence total plant fitness and thus help explain the adaptive value and evolution of flower colour diversity.     

Causal analysis of the diversity of medusae in East China Sea

Based on the maritime data collected from 23°30′–33°00′ N and 118°30′–128°00′ E of the East China Sea (ECS) in four seasons during 1997–2000, the dynamics of medusae diversity and their causes were analyzed. A total of 103 medusae species were identified, and these species mainly distributed in the southern and northern offshore areas of the ECS. Species diversity index (H′) of medusae was higher in the south than those in the north, higher in summer and winter than in spring and autumn, and higher in offshore than in the nearshore areas. The species number was closely correlated with H′ value, whereas the abundance of species had no significant relationship with the diversity index. The lower H′ value of the nearshore in spring and autumn resulted from the aggregation of Muggiaea atlantica in the south nearshore and Diphyes chamissonis in the north nearshore. In addition, water temperature, followed by salinity, is the main environmental factor influencing the distribution of species diversity. The H′ value was related to the water temperature at the 10 m layer in winter and spring, and it was associated with the surface water temperature in summer and with the 10 m-salinity-layer in autumn. In spring and summer, the isoline distribution of H′ value reflected the direction of the Taiwan Warm Current and the variation of the water masses in the ECS. In winter, the isoline of the H′ value indicated the incursion of Kuroshio current. In conclusion, the H′ isoline is an good indicator for water masses in ECS. __________ Translated from Biodiversity Science, 2006, 14(6): 508–516 [译自:生物多样性]     

In vitro induction of mutation in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) and isolation of mutants with improved yield and fiber characters

This paper describes a protocol to develop cotton mutant lines with improved yield and fiber characters. Immature ovules [(15-day post-anthesis ovules (dap)] were irradiated with 10–50 Gy gamma rays and treated with 1–5 mM EMS and SA to investigate the stimulatory effects of mutagenic treatments. During the subsequent field trials, the mutant lines showed significant variations from control lines. Lower dose/concentration of mutagenic treatments effectively stimulate the agronomical characters like early flowering, plant height, number of bolls, yield of seed cotton, ginning percent, seed index, harvest index and fiber characters while exposure at higher dose/concentration results in lowering the value of the parameters. Consequently, we use this approach to induce genetic variability for obtaining novel mutant cotton cultivars. Among the 19 different mutant lines isolated from the study, M7 showed higher morphological variations in terms of yield characters such as plant height, number of bolls, yield of seed cotton, ginning percent and fiber characters. Significant increase in cellulose content was also noted in mutant lines, whereas moderate increase was observed in total fiber units of the mutant lines. The selected cotton mutant lines for cultivars were investigated systematically; these lines significantly increased the potential for agronomical enhancement of cotton yield.     

Fruit production in Sorbus aucuparia L. (Rosaceae) and pre-dispersal seed predation by the apple fruit moth (Argyresthia conjugella Zell.)

Variation in fruit production and pre-dispersal seed predation by Argyresthia conjugella was studied in␣four populations of Sorbus aucuparia in northern Sweden.␣The number of infructescences, fruits per infructescence, consumed seeds and developed unattacked seeds per fruit were scored in marked trees from 1984 to 1990. The results showed that the number of fruits produced in each population determined the number of seed predators occurring in the host population, as the yearly number of seed predators was significantly and positively correlated with yearly number of fruits, in all but one population. The seed predators showed a delay in response to variation in number of fruits produced. This lag in response resulted in a large proportion of fruits being attacked and seeds consumed in a bad fruiting year that followed a good fruiting year, and vice versa. The proportion of fruits attacked and seeds consumed was largest in the population showing the greatest between-year variation in fruit production and lowest in the population showing the lowest between-year variation in fruit production. Furthermore, the individuals within the former population were synchronised, while they were not in the latter population. These results contradict one of the possible explanations of mast-seeding, where large synchronised between-year variation is supposed to reduce pre-dispersal seed predation. Instead, differences in attraction of the seed predator to differences in fruit crop size could explain the observed difference in seed predation between the two populations with opposite fruiting patterns. Within each population, irrespective of year, the proportion of fruits attacked and seeds consumed was independent of a tree's fruiting display. Therefore, trees with high fruit production, despite harbouring the largest number of seed predators, produced the largest number of developed seeds in absolute numbers, compared to trees that produced few fruits. Received: 25 February 1996 / Accepted: 30 November 1996     

Variability and divergence in Pongamia pinnata (L.) Pierre germplasm – a candidate tree for biodiesel

Three explorations were undertaken in South East Coastal zone of India covering parts of Andhra Pradesh (AP) and Orissa states to collect Pongamia pinnata (L.) Pierre germplasm during March–June 2007. A total of 123 accessions were collected and seed data recorded were analyzed for morphometric traits viz., seed length, seed width, seed thickness, 100‐seed weight and oil content. Variation in the collected germplasm was analyzed using anova , simple measures of variation and D² statistics. Significant genetic variability between seed traits and oil content and association among the seed traits was recorded. Phenotypic variance was higher than genotypic variance for all the characters indicating dominant role of environment. High heritability (broad sense) for 100‐seed weight (97.6%) and oil content (86.7%) indicated the reliability of these characters as selection criteria for plus trees. Genetic gain was maximum for 100‐seed weight (62.6%) followed by oil content (30.5%). D² analysis grouped the accessions into 12 clusters. Cluster XII and cluster IX were the most diverse based on the intercluster distance. Based on the observed diversity, Chittoor, Srikakulam and Adilabad districts of AP are most suitable for collecting diverse germplasm lines and also for in situ conservation.