Higher Number Of Seeds Research Articles

English

Although soybean flowers are produced abundantly, a large number of flowers and young pods abort naturally. Abortion reduction may result in an increased number of pods, thus leading to a growth in grain yield. The objective of this study was to evaluate the effect of benzyladenine application on soybean pod abortion and, consequently, to increase the productivity of soybean cultivation. The soil of the experimental area is classified as oxisol. After soil analysis, fertilization and pH correction were performed according to technical recommendations for cultivation. Pioneer 98Y12 RR soybean was sown by mid-November, during the rainy season. Benzyladenine application at the end of flowering, with pods of about 1.5 cm length, provided a significant increase in productivity of the species for all used concentrations, with the treatment of 300 mg L-1 corresponding to the highest increase, around 11%. The increase in productivity was determined by the higher number of total pods fixed to the plants by reason of abortion reduction in the three canopy positions. Other factors that contributed to the increased productivity were the higher number of seeds per plant, higher weight and seed diameter. Benzyladenine application is a promising practice for getting high productivity in the cultivation of soybean. Key words: Growth regulator, abortion, grain yield.

Effect of weeding on the growth, yield and yield contributing characters of mungbean (Vigna radiata L.)

An experiment was conducted at the Agronomy Field Laboratory of Bangladesh Agricultural University, Mymensingh to assess the effect of weeding on growth, yield and yield contributing characters of mungbean (Vigna radiata L.) cv. BINA mung- 4 during October 2011 to February 2012. The experiment was laid out in a randomized complete block design with four replications. The trial comprised seven treatments namely, T1 = no weeding, T2 = one-stage weeding (Emergence-Flowering), T3 = one-stage weeding (Flowering-Pod setting), T4 = one-stage weeding (Pod setting- Maturity), T5 = two-stage weeding (Emergence-Flowering and Flowering-Pod setting), T6 = two-stage weeding (Flowering-Pod setting and Pod setting-Maturity) and T7 = three-stage weeding (Emergence-Flowering and Flowering-Pod setting and Pod setting-Maturity). The growth parameters such as relative growth rate (0.075 g g-1 day- 1) and net assimilation rate (0.075 g m-2day-1) showed the best performance with T2 at one-stage weeding condition (Emergence-Flowering). Three-stage weeding ensured the highest plant height (58.62 cm) as well as the highest number of branches (4.45) and leaves (10.34) plant-1. Dry weight plant-1 (12.38g) was highest from three stage weeding and the lowest from no weeding treatment. The highest number of pods (22.03) plant-1, the longest pod (5.95 cm), the highest number of seeds (17.07) pod-1 and the highest seed yield (1.38 t ha-1) were obtained from three-stage weeding (Emergence-Flowering and Flowering-Pod setting and Pod setting-Maturity) in mungbean. On the other hand, the lowest seed yield was obtained under no weeding condition. The highest seed yield resulted in higher biological yield (4.70 t ha-1) and the highest harvest index (37.15%) in three-stage weeding and the lowest from no weeding. Number of pods plant-1, length of pod, number of seeds pod-1 and 1000-seed weight showed highly significant positive correlations with seed yield. These parameters strongly influenced the growth, yield and yield contributing characters of mungbean (Vigna radiata L.) DOI: http://dx.doi.org/10.3329/jbau.v11i1.18209 J. Bangladesh Agril. Univ. 11(1): 53-60, 2013

Seed priming effect on the number of rows per ear, grain weight and economic yield corn in Sistan region

To study the effect of seed priming on maize under drought stress experiment was split plot based on randomized complete block in three replications In 2012 the Research Center Zahak Was conducted. Subplots seed priming with potassium nitrate solution in five levels (control, 0.5%, 1%, 1.5% and 2%) and three levels of stress as a major factor (control, drought stress at vegetative stage (5 leaflets) to enter the reproductive phase, drought stress at reproductive stage until harvest), respectively. Maximum number of rows per ear on average compared to non-stress conditions (14.27) was observed. The results of the analysis of variance showed that the priming effect on the number of rows per ear was statistically significant at the one percent level. So that a comparison can be inferred from the table, the highest number of seeds in a row, the concentration of potassium nitrate (15.04), respectively. So that the comparison is taken out of Length of ear in terms of highest stress (20.92 cm) was observed. So that the comparison is taken out one of the highest concentrations of nitrate in Length of ear (22.05 cm), respectively. So that the comparison is taken out of Length of ear in terms of highest stress (225.67 mg) was observed. So that the comparison is taken out top thousand seed weight percent potassium nitrate at a concentration (269.7 g), respectively. So that the comparison is taken out of the economic performance of the highest non-stress conditions (2.28 t/ha) was observed. So that the comparison is taken out of the economic performance of the highest concentration of potassium nitrate (20.3 ton/ ha), respectively.

Estimation of genetic variability and association analysis in the indigenous landraces of Urdbean (Vigna mungoL. Hepper) of Andaman islands

The morphological differences among 28 promising urdbean landraces and genotypes was planted in the field to estimate the genetic variability, interrelationship for yield and yield attributing traits under tropical islands conditions. The results revealed that there was sufficient genetic variability in the population for plant height, number of branches per plant, number of pods per plant and seed yield per plant, due to high genotypic and phenotypic variances for these traits. Hence, yield improvement in urdbean would be achieved through selection for the above characters. The higher magnitudes of heritability, GCV and genetic advance were observed for plant height followed by number of branches per plant and seed yield per plant. High heritability values associated with high genetic advance were obtained for seed yield per plant, pods per plant and other yield attributing traits, except for number of seeds per pod. High heritability with moderate genetic advance was recorded for 100-seed weight and number of seed per pod. Correlation studies indicated that pods per plant, branches per plant pod length, seeds per pod and 100-seed weight showed highly significant and positive correlation with seed yield per plant. Path coefficient analysis showed that the criteria can be applied visually during bulk selection in early generation and subsequently in advanced generation for pure line selection based on individual plant by selecting genotypes with higher number of pods per plant and higher number of seeds per pod.

Effect of added barley chromosomes on the flowering time of new wheat/winter barley addition lines in various environments

The heading characters and morphological traits of two partial sets of wheat–barley disomic addition lines, namely Mv9kr1/Igri and Asakaze/Manas, were evaluated under controlled environmental conditions in a phytotron under long-day, short-day and non-vernalised conditions and in field-sown experiments. The winter barley chromosome additions significantly influenced the flowering time of wheat both in the controlled environment test and under field-sown conditions. Of all the barley addition lines, the effect of the 4H and 7H additions was the most characteristic. The 7H addition lines were the earliest in both cultivar combinations in each treatment. In the Mv9kr1/Igri combination the 4H addition was the latest under all the environmental conditions. In the Asakaze/Manas combination 4H addition was the latest under short-day and long-day illumination in the phytotron but the 6H addition was the latest without vernalisation and in the field in 2012. There was 12 and 11 days difference between the flowering times of the 7H and 4H Mv9kr1/Igri and Asakaze/Manas addition lines in the field in 2012, which increased to 52 and 44 days under short-day illumination in the phytotron. In the winter wheat background, the addition of 2H carrying the photoperiod sensitivity gene Ppd-H1 decreased the flowering time under the short photoperiod regime, but had a very strong delaying effect under field-grown conditions. Considering the yield components under field conditions, 4H was the most fertile of the addition lines, while 7H showed the highest tillering capacity, and Igri 3H had good tillering capacity and the highest number of seeds per plant.

Variations in soil seed banks of abandoned farmlands of various ages in Umukabia Umuagbom, Abia State, Nigeria

A 3 x 5 Factorial Experiment in Randomized Complete Block design Experiment was used to study seeds stocked in soils of four abandoned farmlands and a secondary forest regrowth at Umukabia, Nigeria. Soil monoliths 25.0 x 25.0 x 10.0 cm were collected from the depths 0-10 cm and 10.0-20.0 cm from four abandoned farmlands and a secondary forest regrowth in the months of August, September and October, 2008. The experiment was replicated twice at each site for each month. Sieving- floatation method was adopted and two sieves of 1.85 mm and 0.80 mm mesh opening were used to sieve each soil monolith. The left over after sieving were air dried under the room temperature. The dried soil materials for each sample were viewed with a 10 magnifying hand lens to sort and enumerate the number of seeds contained in each sample. The seeds found at both depth of 0 - 10 cm and 10 - 20 cm were identified. After collection of the seeds, the data obtained were analyzed and the differences between the treatment means were separated using Fisher’s - Least Significant differences (F-LSD) at P<0.05. The total number of seeds counted from soil monoliths collected from the depths of 0.0 – 10.0 cm and 10.0-20.0 cm were 344 and 99, respectively. For months, September with a mean of 12.90 seeds had the highest number of seeds while seven year old abandoned farmland with a mean of 14.67 seeds had the highest number of seeds amongst the various abandoned farmlands. Except seeds of Canariums chweinfurthii and Dialium guineense no other tree seeds were recorded. It was concluded that man should help in tree seeds dispersal and seedlings maintenance within abandoned farmland of the tropical rainforest to minimize the danger of most tree species being classified as being rare or endangered. © 2013 International Formulae Group. All rights reserved.Keywords: seed stocked, soil, sieving-floatation, secondary forest, regrowth.

Fallen logs as sources of patchiness in chenopod shrublands of South Australia

While numerous studies focus on heterogeneity created by living plants and animal diggings in arid lands, little information exists on the pattern and role of heterogeneity created by large woody debris. We studied soil nutrient content, volumetric water content, and vegetation associated with the presence of logs in sites subject to different grazing intensity in a chenopod shrubland of South Australia. Soil volumetric water content was lower close to logs, and the soil there dried faster after rains. Organic carbon was higher, but available phosphorus was lower in soil associated with logs. We documented greater seedling emergence, species richness and diversity, and greater annual plant biomass next to logs. Our results were similar in the sites with high and low grazing pressure, the latter having higher numbers of seeds and species in the germinable soil seed bank. Logs in this system create patches that differ in properties from other patches in the system (i.e. those created by perennial plants, depressions, or diggings). Logs constitute a unique microenvironment which affects the plant community structure and may enhance the diversity of the system, and should be considered in management schemes.

Grassland connectivity by motor vehicles and grazing livestock

In addition to habitat loss and fragmentation, agricultural change has led to a change in seed dispersal processes in the rural landscape through a loss of structural and functional connectivity. Here, human‐mediated dispersal vectors are prevalent, and we explored whether the loss of connectivity via free‐ranging livestock could be mitigated by the increase in roads and motor vehicles. We found that structurally, 39% of all valuable semi‐natural grassland habitats in southern Sweden are adjacent to public road verges, which in the rural landscape are often considered to be suitable habitat for grassland species. Additionally, by collecting mud attached to cars and farming machinery and manure from livestock (cattle, horse, sheep) grazing semi‐natural grassland pasture, we found that motor vehicles are also capable seed dispersers. A similar number of species were dispersed by both vectors, although the composition of samples was quite different. Motor vehicles dispersed more grassland specialists than invasive species, although in much lower abundances than did grazing livestock. Despite these differences, motor vehicles were found to be able to disperse species with the same kinds of dispersal traits as livestock. A high number of seeds, species and specialists in manure samples means that greater movement of livestock is desirable to increase functional grassland connectivity. However, effective management could improve the suitability of roadsides as grassland corridors and increase the availability of seeds for long‐distance human‐mediated dispersal via cars and tractors. Our results suggest that in many rural landscapes, connectivity by road networks could help mediate habitat loss and fragmentation of grasslands. However, such effects can be context dependent, and the connectivity provided by roads could have serious negative consequences in other regions.

A Comparative Study on Local and Newly Introduced Rice Varieties in Ebonyi State of Nigeria based on Selected Agronomic Characteristics

The Choice of rice varieties by farmers and the rate at which farmers in Ebonyi state go for new rice varieties at the expense of indigenous varieties have become a source of worry to scientists. We assessed the agronomic characteris- tics of 15 selected indigenous and newly introduced hybrid rice varieties in Ebonyi State, Nigeria. The Rice cultivars were grown under the same conditions and screened for morpho-agronomic traits. Significant variation (P<0.05) was detected among the 20 rice varieties for all the traits evaluated. The results showed that plant height ranged between 144.01 cm in Mass (I) and 76.00 cm in Chinyeugo. Cv. E4197 had the highest value of 38±0.02 cm for panicle length and Chin- yereugo had the highest value of 6.3g ± 0.03 for panicle weight. Leaf area showed the highest value of 63.8cm 2 ± 0.01 in Mass (I). Flowering time ranged from 138 ± 0.1days in Mass (I) to 68 ± 0.04 days in Chinyereugo while Mass (II) and E4077 took the shortest period of 14 days after flowering to mature. Cv. Co-operative had high number of seeds per panicle (139 ± 0.19). Chinyereugo had the highest value of 25.9g ±1.4 for 1000-grains weight. The grain of E4314 was the longest (8.00 mm ± 0.89) of the varieties studied. The grains of Awilo had a grain width of 2.62mm ± 0.04, while E4197 had the highest value for grain width of 4.1 mm. Farmers should, therefore, be critical in accepting new varieties that may not be comparably outstanding in a holistic sense, in order to preserve the integrity of the all-cherished indigenous rice varieties .

Large number of flowers and tertiary branches, and higher reproductive success increase yields under salt stress in chickpea

Salinity is a major problem worldwide and improving salt tolerance of chickpea (Cicer arietinum L.) will allow expansion of production to more marginal areas. Plant reproduction suffers under salt stress in chickpea, but it remains unclear which process is most affected and what traits discriminate tolerant from sensitive lines. Three pot experiments were carried out to compare the effects of salt application (17g NaCl kg−1 Alfisol) at sowing (SS) and at the start of flowering (SF) on growth, canopy transpiration, plant architecture, and flower, pod and seed development (timing, numbers, mass, abortion). Six pairs of tolerant/sensitive lines with similar flowering times within each pair, but different among the pairs, were used. Shoot biomass was similar in tolerant and sensitive lines in the SS and SF treatments, whereas the seed yield decreased more under SS and SF treatments in the sensitive lines. The flower, pod and seed numbers within all pairs was higher in the tolerant than in the sensitive lines in the non-saline controls, but the differences in numbers of seeds and pods further increased in both the SS and SF treatments. By contrast, neither the duration of flowering or podding, nor the percentage of flower or pod abortion, discriminated tolerant from sensitive lines. In non-saline controls the numbers of primary branches was 100% higher across the sensitive lines, whereas the number of tertiary branches was 8-fold higher across tolerant lines. The relative transpiration of the tolerant lines in the salt treatments was above that for the sensitive lines in three pairs of tolerant/sensitive lines, but did not differ within two pairs. Our results demonstrate that constitutive traits, i.e. numbers of flowers and tertiary branches, and adaptive traits, i.e. high number of seeds under salt stress, are both critical aspects of salinity tolerance in chickpea.

English

Kinnow is the major fruit of Pakistan and has a high export potential due to its excellent fruit and juice quality. However, high number of seeds (25 ± 5) per fruit is limiting its export on a large scale. Benefiting from the induced mutations for selectivity, especially in the vegetatively propagated fruit crops like citrus, induced mutation for seedlessness in Kinnow with gamma irradiation of dormant bud which was attempted at the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad. Dormant bud irradiation-cum-grafting technique was employed, using the Citrus jambhiri rootstock for propagation of the scion. A sparse seeded (5 ± 3 seeds/fruit) mutant was evolved from an exposure dose of 20 Gy. The mutant was put to the conventional propagation up to mV 5 , for confirmation of the continuity of the mutation. The sparse seeded mutation was found to be a solid and stable one. The quality parameters in fruit and juice of the mutant were comparable with its parent. Key words : Kinnow, seedlessness, dormant bud, gamma irradiation, mutant kinnow.

Characterization of Prosopis cineraria (L.) Druce germplasm with suitable horticultural traits from the hot arid region of Rajasthan, India

Sixteen germplasm accessions of Prosopis cineraria with suitable horticultural traits were identified from north-western Rajasthan, India, propagated clonally by budding on seedling rootstock and maintained in the field gene bank. Morphological characterization of seven-year-old trees of these accessions by 21 traits indicated a lot of variation among the accessions tested. Higher number of flowers per raceme was found in accession CIAH/K2, higher width of ripened pod in CIAH/K5, higher number of seeds per pod in CIAH/K12 and a higher weight of seed per pod in CIAH/K6. Overall, CIAH/K16 was found to be a superior genotype for most of the useful traits. High significant positive correlation was obtained with traits useful for horticultural values. Out of 62 random decamer primers for random amplification (RAPD) reaction, and four minisatellite core sequence for direct amplification of minisatellite DNA (DAMD) screened with these accessions, 12 RAPD and 2 DAMD primers were found polymorphic. Average polymorphism resolved by these markers among the accessions was 93.2%. Genetic diversity revealed by Jaccard’s co-efficient was between 0.11 and 0.77, and four major clusters were identified among these accessions by phylogenetic analysis using NTSYSpc-2.02e software. This study shows the existence of high genetic diversity within these accessions.

Effects of Changes in Source–Sink Relation in Different Planting Dates on Yield and Yield Components of Soybean Cultivars

Split-split plots experimental design based on randomized complete block design was conducted at the Baiekola Agricultural Research Center in 2010 to study the effects of changes in source–sink on the yield and yield components of soybean cultivars planted at different dates. Factors studied in this experiment included planting date, as the main plot, at two levels (June 6, June 27), cultivars (Line 032, 033, Sari or JK, and Telar or BP), as the sub plot, and five levels (including the removal of the top, the middle, and the bottom one thirds of the leaves, removal of one third of the flowers, and the control treatment as the sub-sub plot. Results of analysis of variation showed that the various cultivars were significantly different in all the studied traits at (P<0.01) probability level. Seed yield at the first planting date (184.03 g. m-2) was 11.18% lower than that at the second planting date (163.45 g.m-2). The highest seed yield was obtained in Line 033 with 219.96 g.m-2, which was statistically different from the those of all the other cultivars except that of Line 032, which was 186.19 g.m-2. The higher seed yields in Line 033, as compared with other treatments, were accompanied by the highest 1000 seed weight (242.93 g), the highest number of pods per plant on the main stem (43.31) and on the auxiliary stems (33.37), and the relatively high number of seeds per pod (2.37). Results of applying limitations of the sink–source treatments on seed yield showed that the highest seed yield was obtained in the control treatment (212.17 g.m-2). With the removal of the top one third of the leaves, the yield decreased severely so that the least seed yield in this treatment (138.08 g.m-2) was 35% less than that of the control. In the treatments of removing the middle one third of the leaves and one third of the flowers, the seed yield was reduced by 28.5 and 21.8%, respectively, as compared with the control. The least effect on seed yield was observed in the treatment of removing the bottom one third of the leaves, in which the yield was 201 g.m-2, or only 5.25% less than that of the control. The high yields in the control treatment of applying sink–source limitations were accompanied by high 1000 seed weight (220.217 g), the maximum number of seeds per pod (2.53), the maximum number of pods on the main stem (46.40), and, finally, the maximum number of pods per stem (74). The least seed yield in applying the treatment of the removal of the top one third of the leaves was also accompanied by the least 1000 seed weight (199.59 g), the fewest number of seeds per pod (2.27), the fewest number of pods per main stem (30.62), and the fewest number of pods per plant (53).

Caractérisation phéno-morphologique de quelques lignées de fève (Vicia faba L.) sélectionnées et adaptées aux conditions de culture dans les régions arides en Tunisie

The objective of the present study was to produce a pheno-morphological characterization of 13 faba bean lines selected by the Institute of Arid Regions from 42 local populations. The pheno-morphological variability of these lineages was observed and followed from planting through to seed maturity by biometric measurements and by qualitative evaluations on different plant parts. Morphological characteristics were described by using the UPOV (2000) descriptor. The analysis of results made it possible to distinguish between 2 groups based on precocity and hundred-seed weight. The first group was represented by line 8 which differs from others by the fact that it was the earliest and had the highest one hundred-seed weight. The second group was divided into 3 subgroups that differed in terms of plant vigour and productivity. The first subgroup was characterized by a lower number of flowers per raceme, a hundred-seed weight average ranging from 162.96 g to 165.24 g and a highest number of seeds per pod. This first subgroup contained the lines 5, 10, 11, 12 and 13. The second subgroup included lines 6, 7 and 9 which were the most homogenous on 50 % owering date, plant height and length of lea et. The latter subgroup included the lines 1, 2, 3 and 4, characterized by a highest number of pods per plant, number of stems per plant, and number of flowers per raceme. These lines should be preserved and valued for the varietal improvement programs of Vicia faba. Successive selection should be practiced until a more productive synthetic variety is obtained that is better adapted to the dry conditions of South Tunisia.Key words: Phenology, agromorphology, characterization, Vicia faba

Relative success of self and outcross pollen after mixed- and single-donor pollinations in Eucalyptus grandis

A previous observation that self-pollen tubes traversed the style at a slower rate than cross-pollen tubes in Eucalyptus grandis and E. urophylla suggested the presence of cryptic self-incompatibility (CSI) in these species. The aim of the present study was, with the help of molecular markers, to examine the siring ability of self- and cross-pollen in a single clone of E. grandis, after both mixed- and single-donor pollinations, in order to confirm the presence of CSI. Single-donor cross-pollinations set a significantly higher number of seeds per flower pollinated compared to those performed with self-pollen, while there were no significant differences between the open control and single-donor self-pollinations. Molecular markers revealed that 100% of the progeny from mixed-donor pollinations were outcrossed, confirming the competitive advantage of cross-pollen. In addition, there was a significant change in the self:outcross seed ratio between single- and mixed-donor pollinations, suggesting that the observed deficit of selfed seeds in mixed-donor fruits could be the result of differential pollen tube growth. From the extremely low seed yields following single-donor self-pollinations, it is clear that an additional incompatibility mechanism is operating in E. grandis, and this is suggested to be late-acting self-incompatibility, acting before fertilisation.

From seed production to seedling establishment: Important steps in an invasive process

It is widely accepted that exotic invasive species are one of the most important ecological and economic problems. Reproductive and establishment traits are considered key features of a population expansion process, but few works have studied many of these simultaneously. This work examines how large the differences are in reproductive and establishment traits between two Fabaceae, the exotic invasive, Gleditsia triacanthos and the native, Acacia aroma. Gleditsia is a serious leguminous woody invader in various parts of the world and Acacia is a common native tree of Argentina. Both species have similar dispersal mechanisms and their reproductive phenology overlaps. We chose 17 plants of each species in a continuous forest of the Chaco Serrano Forest of Córdoba, Argentina. In each plant we measured fruit production, fruit removal (exclusion experiments), seed predation (pre- and post-dispersal), seed germination, seed bank (on each focal tree, three sampling periods during the year), and density of seedlings (around focal individuals and randomly in the study site). Gleditsia presented some traits that could favour the invasion process, such as a higher number of seeds per plant, percentage of scarified seed germination and density of seedlings around the focal individuals, than Acacia. On the other hand, Gleditsia presented a higher percentage of seed predation. The seed bank was persistent in both species and no differences were observed in fruit removal. This work highlights the importance of simultaneously studying reproductive and establishment variables involved in the spreading of an exotic invasive species. It also gives important insight into the variables to be considered when planning management strategies. The results are discussed from the perspective of some remarkable hypotheses on invasive species and may contribute to rethinking some aspects of the theory on invasive species.

Fatores relacionados à produção e desenvolvimento de afilhos em trigo

Wheat plants use different strategies for achieving grain yield. Among them, one can point out the compensatory mechanisms among the grain yield components: number of ears per unity of area, number of grains per ear and grain weight. Grain yield in wheat is mostly represented by tiller production, providing that plants are adequately spaced from each other and that weather conditions are favorable to stimulate tillering. Thus, it is necessary to understand the different factors that are related to tiller production and development. The signalling pathways and the morphophysiological responses to environmental factors such as light quality, soil fertility and water availability are also important. The correct adjustment of these factors, as presented in this review, is essential for maximizing grain yield. In the breeding programs it is important make efforts to use genotypes with low number of tillers, even with a higher number of seeds per hectare, to maximize grain yield, reducing the dependence on environmental variables.

Studies on the pattern of occurrence of soil seed bank of monodora myristica in Umuahia, Abia State, Nigeria.

The study on soil seed bank of three stands of Monodora myristica was carried out in Ohiya, Umuahia South of Abia State, Nigeria. Three soil depth of 0-5cm, 5-10cm and 10-20cm (control) were dug at four cardinal points from the stands at a distance of 0m, 3m and 7m (i.e. control) respectively. The total number of seeds deposited at the 0- 5cm depth at 0m (8.583), 3m (14.250) and 7m (3.000) were significantly higher than that deposited within the 5-10cm (3.333, 5.917 and 0.833) and the 10-20cm depth (0.250, 1.750 and 0.000) respectively. Over 70% of the seeds of Monodora myristica occurred within the 0-5cm depth, 25% were deposited at the 5-10cm depth while the control had about 5% seed occurrence. The highest number of seeds occurred at the distance of 3m while the control had the lowest. The highest level of interaction between distance and soil depth occurred within the 0-5cm and 3m. The pattern of seed occurrence in the soil may be attributed to the size and shape of the seeds of this tree specie.

Seed dormancy and germination in the Australian baobab, Adansonia gregorii F. Muell.

AbstractSeeds of the iconic Australian baobab Adansonia gregorii display physical dormancy (PY) and germinate readily once they become water permeable, a trait found in most other species in this genus. Highest germination (100%) was observed when seeds were placed in concentrated sulphuric acid (H2SO4) for 24 h, although exposure to H2SO4 for 6–12 h also resulted in &gt;85% germination. Exposure to boiling water for 1–5 min was far less effective in promoting germination (0–23%), although a high number of seeds were water permeable (67–99%) following boiling water treatment. However, the majority of these water-permeable seeds appeared to have been injured by boiling water exposure. Germination at warmer temperatures (30 or 35°C) was found to be optimal (81–83% germination) and proceeded rapidly, with maximum germination occurring after incubation for only 8 d. In comparison, germination at 15–25°C resulted in 3–67% germination over a longer time frame (up to 20 d). While seeds of A. gregorii display PY they are unusually sensitive to dipping in boiling water and are therefore atypical when compared to most other Adansonia species.

TESTE DE PATERNIDADE E AVALIAÇÕES AGRONÔMICAS DE POSSÍVEIS HÍBRIDOS DE TANGERINEIRA ‘SUNKI’

A produção de citros está espalhada em todos os continentes agricultáveis e no Brasil ela representa o maior volume de frutas produzidas. O porta-enxerto é extremamente importante no estabelecimento de um pomar de boa qualidade. Na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, está localizada uma população de híbridos cítricos, implantada em 1990 e oriunda de polinização aberta, sendo o genitor feminino o tangeleiro ‘Lee’ [Citrus clementina Hort. ex Tan. x (C. tangerina Hort. ex Tan. x C. paradisi Macf.)]. Dentre os híbridos deste pomar foram selecionadas quatorze plantas com características morfológicas semelhantes as do porta-enxerto tangerineira ‘Sunki’ (C. sunki Hort. ex. Tan.). Para confirmar a paternidade dos híbridos foram utilizados marcadores moleculares do tipo microssatélites. A análise molecular permitiu identificar onze híbridos que não tiveram a ‘Sunki’ como parental masculino. Os demais híbridos, potenciais híbridos de tangerineira ‘Sunki’, genótipos 49, 77 e 92, tiveram maior taxa de poliembrionia, maior número de plântulas emergidas por semente e maior número de sementes produzidas por fruto quando comparadas com a tangerineira ‘Sunki’.