Mulching as an alternative technique for weed management in mandarine orchard tree rows

Peer reviewed

Seed biometric parameters in oil palm accessions from a Brazilian germplasm bank

The objective of this work was to evaluate the morphological diversity of oil palm seeds and to cluster the accessions according to their morphological characteristics. Forty-one accessions from the oil palm germplasm bank of Embrapa Amazônia Ocidental were evaluated - 18 of Elaeis oleifera and 23 of E. guineensis. The groups were formed based on morphological characteristics, by principal component analysis. In E. oleifera, four groups were formed, tied to their region of origin, but with significant morphological differences between accessions from the same population. For tenera-type E. guineensis seeds, three widely divergent groups were formed, especially as to external parameters, which differentiated them from the other ones. The parameter endocarp thickness stood out in intra- and inter-population differentiation. For dura-type E. guineensis, three groups were formed, with larger seeds and thicker endocarps, which differed from all the other ones. The variability observed for seed characteristics in the analyzed accessions allows the establishment of different groups, to define strategies for genetic improvement.

Conductivity test in seeds of different passion flower species

The objective of this work was to evaluate the use of the conductivity test as a means of predicting seed viability in seven Passiflora species: P. alata, P. cincinnata, P. edulis f. edulis, P. edulis f. flavicarpa, P. morifolia, P. mucronata, and P. nitida. Conductivity of non-desiccated (control), desiccated, and non-desiccated cryopreserved seeds was determined and related to their germination percentage. The obtained results suggest that the electrical conductivity test has potential as a germination predictor for P. edulis f. flavicarpa seed lots, but not for the other tested species.

Influence of the temperature in germination of seeds of jabuticaba tree

The jaboticaba tree (Myrciaria spp.) is originated from the center-south of Brazil and presents different types. It's a medium size tree, with tendency to form a crown with great number of branches. A characteristic considered as limitant for the commercial crop is the great juvenility, advicing producing good rootstocks of seedlings and graft wanted varieties, and other vegetative processes. With the purpose of evaluating the effect of temperature on germination of three clones of jaboticaba tree, was carried out a laboratorial research. It was observed influence of the temperature on germination. The highest percentage of germination was obtained at low temperature (15ºC and 20ºC). When it was used the temperature of 35ºC, two clones had only 8% of germination, while the other one was verified 35%. These values show the possibility of the ocurrence of variability among the clones of jaboticaba tree.

Seedling development and biomass as affected by seed size and morphology in durum wheat

This work evaluated the effect of seed size and morphology on the development and biomass of durum wheat seedlings. Three different seed-grading sizes selected by sieving were used in glasshouse experiments, and a set of three developmental and 23 biomass-related indices were measured on eight genotypes, at two moisture levels. The influence of seed size on seedling development was studied at high and low temperatures (22\12 mC, and 15\5 mC day\night temperatures, respectively), in growth chambers. The area of the seed and the area of the embryo were the seed morphological traits most affected by seed size. Seed size was strongly associated with seedling development and seedling biomass until the complete extension of the first two leaves, at the fourth leaf stage. The rate of first-leaf growth and the area of the first leaf were the developmental and biomass traits, respectively, most sensitive to seed-grading size.

Germination : a means to improve the functionality of oat

Selostus: Idättämällä voi muokata kaurasta uudenlaisia elintarvikeraaka-aineita

Lipid peroxidation and seed emergency in progenies of the yellow passion fruit plant

The objective was to evaluate the percentage of emergency plantlets and lipid peroxidation in seeds of 29 half-sib progenies of yellow passion fruit (Passiflora edulis Sims.) after 24 months under storage. The experimental design was completely randomized, with four replications of 50 seeds each, from which the treatments were the progenies (1-29). The evaluation of the percent plantlet emergency was accomplished at 14 and 28 days after sowing. The lipid peroxidation of the seeds was expressed as malondialdehyde (MDA) content that was determined by the TBARS method. Approximately 21% of those half-sib progenies maintained the viability of their seeds for twenty-four months under storage. The results point out a remarkable genetic variability for vigor and emergency of the yellow passion fruit plantlets, with occurrence of individuals with high and other ones with low capacity to maintaining the physiologic quality of their seeds after storage.

Monitoring the viability of citrus rootstocks seeds stored under refrigeration

The citrus nursery tree is produced through the bud grafting process, in which rootstock is usually grown from seed germination. The objective of this research was to evaluate, in two dissimilar environmental conditions, the viability and polyembryony expression of five citrus rootstocks seeds stored in different periods under refrigeration. The rootstock varieties evaluated were: Rangpur lime (Citrus limonia Osb. cv. Limeira), Trifoliate orange (Poncirus trifoliata Raf. cv. Limeira), Citrumelo (P. trifoliata x C. paradisi Macf. cv. Swingle), Sunki mandarin (C. sunki Hort. ex Tanaka) and Volkamer lemon (C. volkameriana Ten. & Pasq. cv. Catania 2). The experimental design was the randomized blocks in a 11 x 5 x 2 factorial scheme, evaluating from time zero to the tenth month of storage, the five varieties of rootstock in two environments: germination and growth B.O.D type chamber (Biological Oxygen Demand - Eletrolab Brand Model FC 122) at 25 °C; and greenhouse seedbed with partial temperature control (22 °C to 36 °C) and humidity control (75-85%). The plot had 24 seeds in four replicates, using trays with substrate in greenhouse and Petri dishes with filter paper in B.O.D. chamber. The seed germination rate and polyembryony expression were evaluated monthly. It was concluded that Trifoliate and Citrumelo Swingle seeds can be stored for up to seven months, while Volkamer lemon, Rangpur lime and Sunki seeds can be stored for up to ten months. The polyembryony expression rate was slightly higher when measured in greenhouse than in B.O.D. chamber and remained stable in both environments until the seventh month, from which dropped sharply. Citrumelo Swingle seeds expressed the highest polyembryony rate (18.8%), followed by Rangpur lime and Volkamer lemon (average value of 13.7%), Sunki (9.4%) and Trifoliate (3.2%). Despite some differences among varieties, the viability of rootstock stored seeds can be monitored either in the greenhouse or in B.O.D. germination chamber, the latter being the faster and more suitable method.

Conservation of Campomanesia adamantium (CAMB.) O. berg seeds in different packaging and at varied temperatures

This article aims at evaluating the effects of different packaging and varied storage temperatures on the germination potential of seeds of Campomanesia adamantium Camb. O. Berg. The seeds were packaged in glass, aluminum foil and plastic containers, or maintained inside intact fruits at 5, 10 and 15 ºC during 0, 7, 14 and 21 days. After these periods the seeds were sown in Germitest® germination paper and maintained in incubation chambers at 25 ºC under constant white light for 42 days. Seed moisture contents were evaluated both before and after storage, as well as germination percentages, germination speed index, root and aerial portion of seedlings lengths, and total dry weights. All possible combinations of packing materials, temperatures and storage times were tested, with four repetitions of 25 seeds for each treatment. C. adamantium seeds showed initial water contents of 31.5%. Glass and aluminum packaging were efficient at maintaining the water content of the seeds, and provided greater germination speed index than the other packaging materials. Germination percentages, seedlings lengths and dry weights did not vary among the different temperatures tested. C. adamantium seeds can be stored for up to 21 days at temperatures between 5 and 15 ºC without altering their physiological quality. In terms of cost-benefit efficiencies, these seeds can be stored without significant damage for 21 days while still inside the fruits at temperatures of 5, 10 or 15 ºC.

Biological Flora of the British Isles: Ambrosia artemisiifolia

1. This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation, impacts and management. 2. Ambrosia artemisiifolia is a monoecious, wind-pollinated, annual herb native to North America whose height varies from 10 cm to 2.5 m according to environmental conditions. It has erect, branched stems and pinnately lobed leaves. Spike-like racemes of male capitula composed of staminate (male) florets terminate the stems, while cyme-like clusters of pistillate (female) florets are arranged in groups the axils of main and lateral stem leaves. 3. Seeds require prolonged chilling to break dormancy. Following seedling emergence in spring, the rate of vegetative growth depends on temperature, but development occurs over a wide thermal range. In temperate European climates, male and female flowers are produced from summer to early autumn (July to October). 4. Ambrosia artemisiifolia is sensitive to freezing. Late spring frosts kill seedlings and the first autumn frosts terminate the growing season. It has a preference for dry soils of intermediate to rich nutrient level. 5. Ambrosia artemisiifolia was introduced into Europe with seed imports from North America in the 19th century. Since World War II, it has become widespread in temperate regions of Europe and is now abundant in open, disturbed habitats as a ruderal and agricultural weed. 6. Recently, the N. American ragweed leaf beetle (Ophraella communa) has been detected in southern Switzerland and northern Italy. This species appears to have the capacity to substantially reduce growth and seed production of A. artemisiifolia. 7. In heavily infested regions of Europe, A. artemisiifolia causes substantial crop-yield losses and its copious, highly allergenic pollen creates considerable public health problems. There is consensus among models that climate change will allow its northward and up-hill spread in Europe.

Effect of GA3, KNO3, and removing of basal point of seeds on germination of sweet granadilla (Passiflora ligularis Juss) and yellow passion fruit (Passiflora edulis f. flavicarpa)

Passiflora seeds germinate erratically presenting difficulties for their handling in a greenhouse. The effect of removing of basal point of seeds (RB) and pre-imbibition of seeds of sweet granadilla and yellow passion fruit in 50, 100, 200, and 400 mg mL-1 solutions of gibberellic acid (GA3) or 0.1% KNO3 solution was studied. The experiment was conducted in greenhouses in La Plata, Colombia. Two accessions PrJ1 and PrJ2 of sweet granadilla were evaluated. There were calculated the final percentage of germination (PG), mean germination time (MGT), and the mean germination rate (MGR). The leaf area and dry mass of seedlings were measured 22 days after sowing (das); with this data, specific leaf area and relation root/shoot were calculated. In all cases, the highest germination percentages were achieved treating seeds with KNO3 (89, 92, and 87% for yellow passion fruit, PrJ2, and PrJ1, respectively), but the increase in MGR (3.3 germinated seeds per day) and the decrease in MGT (16 days) were only significant for PrJ1. RB had a significant reduction of PG in all cases (28, 12, and 33% for passion fruit, PrJ2 and PrJ1, respectively). With the increase in the concentration of GA3, PG was reduced for two accessions of sweet granadilla, for yellow passion fruit this trend was not clear, no treatment with GA3 showed significant differences with the control. Leaf area (24.07 cm2) and dry mass of seedlings (135 mg) were significantly higher than seeds previously treated with KNO3 only for PrJ1.The solution of KNO3 0,1% is recommended to improve the germination and initial growth of granadilla seedlings.

In vitro pollen germination and pollen viability in passion fruit (Passiflora spp.)

The use of Passiflora species for ornamental purposes has been recently developed, but little is known about pollen viability and the potential for crossing different species. The objective of this study was to evaluate the pollen viability of six Passiflora species collected from different physiological stages of development through in vitro germination and histochemical analysis using dyes. The pollen was collected in three stages (pre-anthesis, anthesis and post-anthesis). Three compositions of culture medium were used to evaluate the in vitro germination, and two dyes (2,3,5-triphenyltetrazolium chloride, or TTC, and Lugol's solution) were used for the histochemical analysis. The culture medium containing 0.03% Ca(NO3) 4H2O, 0.02% of Mg(SO4 ).7H2O, 0.01% of KNO3, 0,01% of H3BO3, 15% sucrose, and 0.8% agar, pH 7.0, showed a higher percentage of pollen grains germinated. Anthesis is the best time to collect pollen because it promotes high viability and germination. The Lugol's solution and TTC dye overestimated the viability of pollen, as all accessions showed high viability indices when compared with the results obtained in vitro.

Water uptake by Annona diversifolia Saff. and A. purpurea Moc. & sessé ex dunal seeds (Annonaceae)

Annonaceae seeds are known by presenting dormancy mechanisms, whose reports ranging from coating impermeable to the physiological dormancy. By this way, the present study aimed to evaluate water uptake in Annona diversifolia Saff and Annona purpurea Moc & Sessé ex Dunal seeds. For this study, seeds were placed under immersion in distilled water, and used four replicates of 25 seeds of each species, which were weighed during the 480 hours that were immersed. To determine the place of purchase of water, Annona diversifolia seeds were sealed with paraffin at different locations. Based on the results, seeds from both species reached the phases I and II of water uptake, which indicates they are not hard; however, germination (Phase III) was not reached. Annona diversifolia seeds completed Phase I with, 50h and Annona purpurea with 70h from imbibitions begin, which shows that even slowly, water is acquire.

EMS mutagenesis in mature seed-derived rice calli as a new method for rapidly obtaining tilling mutant populations.

Background: TILLING (Targeting Induced Local Lesions IN Genomes) is a reverse genetic method that combines chemical mutagenesis with high-throughput genome-wide screening for point mutation detection in genes of interest. However, this mutation discovery approach faces a particular problem which is how to obtain a mutant population with a sufficiently high mutation density. Furthermore, plant mutagenesis protocols require two successive generations (M1, M2) for mutation fixation to occur before the analysis of the genotype can begin. Results: Here, we describe a new TILLING approach for rice based on ethyl methanesulfonate (EMS) mutagenesis of mature seed-derived calli and direct screening of in vitro regenerated plants. A high mutagenesis rate was obtained (i.e. one mutation in every 451 Kb) when plants were screened for two senescence-related genes. Screening was carried out in 2400 individuals from a mutant population of 6912. Seven sense change mutations out of 15 point mutations were identified. Conclusions: This new strategy represents a significant advantage in terms of time-savings (i.e. more than eight months), greenhouse space and work during the generation of mutant plant populations. Furthermore, this effective chemical mutagenesis protocol ensures high mutagenesis rates thereby saving in waste removal costs and the total amount of mutagen needed thanks to the mutagenesis volume reduction.