The effects of physical seed coat scarification and soaking in hydrogen peroxide (H2O2) were studied to determine presowing treatments that would improve germination in seed of Vangueria infausta. The study involved two experiments, the first conducted in the laboratory, and the second in the nursery. The scarification treatments were: unscarified control; partial removal of the seed coat at the radical end; and total removal of the seed coat. The other treatments involved soaking the seeds in 5 concentrations of H2O2, i.e., 0, 2, 4, 6 and 8%, for 12 h.Generally, less than 70% of the seeds germinated. The best germination results, (71% in the laboratory and 63% in the nursery) were obtained in seeds with partial removal of the seed coat when soaked in 6% H2O2 for 12 h. Germination in other treatments involving partial removal of the seed coat was higher than that of unscarified seed in the nursery, although laboratory values were nearly the same. Seeds whose seed coat was completely removed germinated poorly (5–16%), as a result of rapid water uptake which caused damage to internal seed structures.Hydrogen peroxide application at concentrations of 2–6% positively improved germination, while 8% H2O2 seemed to have a depressive effect. The impact of scarification and H2O2 on other germination parameters is discussed.
Tag: Seed production
Procedures for the seed production of pearl millet varieties.
This is a guide to the techniques required to produce pure and vigorous seed from varieties of this cross-pollinated crop. Multiplication rates, through sequential breeder, foundation, and certified seed stages, are high:3 kg of seed are adequate for sowing 1 ha, subsequently producing 1 tonne of clean seed. Nucleus seed plots (stage 0), sown for regeneration once every 4 years, should be effectively is o- lated . They should be between 0,1 and 0.2 ha in size, and contain at least 3000 plants. Plots of breeder seed(stage1)should similarly be well isolated, and rigorously inspected and rogued, and not more than 1% of off – types should be permit tedatfinal inspection. Plot sizes are normally between 0.1 and 0.5 ha, according to how much certified seed is required, using a conservative multiplication factor of X200. At the end of the foundation seed stage (stage 2), through protective perimeter planting, inspection, and rogueing, off-types should be less than 2%. At the final certified seed stage(3), the permitted level of off-types is 5%. Six points of guidance are given for extension staff to pass on to farmers who(as may be expected) at tempt to multiply their own improved seed.
Floral Structure and Breeding Systems of Manglietia conifera Dandy (Magnoliaceae)
Manglietia conifera Dandy is a fast-growing tree species that has been introduced to China from Vietnam, which has great potential for commercial planting. However, plantation development is hindered by a lack of seed material, due to low natural seed-set in locally grown trees. Thus, we investigated the morphological characteristics of male and female flower organs, and conducted controlled pollination to understand the breeding systems of the species. The individual flower of M. conifera is bisexual, and the stamen group is polymerized at the base of the receptacle. Pollen is symmetrically distributed on both sides. Controlled pollination suggests that apomixis does not occur in M. conifera. Results from the flower structure, pollen–ovule ratio, outcrossing index, and controlled pollination indicated that the breeding system in M. conifera was outcrossing (partially self-compatible, pollinators required), and self-incompatibility occurred in a later stage of embryonic development. Moreover, the self-incompatibility phenomenon was revealed by the abnormal germination of pollen on the stigma. This paper provides a basis for controlled pollination programs of M. conifera.
Pollination and fruit-set of Grevillea robusta in western Kenya
The floral visitors of silky oak, Grevillea robusta A. Cunn. ex R.Br., their foraging behaviour and their effects on fruit-set were studied at Malava, western Kenya. Grevillea robusta is a popular tree for farm plantings in the eastern and central African highlands. Yield of seed has been disappointingly low in some areas and a lack of appropriate pollinators has been suggested as a possible cause. Investigations involved the monitoring of visitors on active inflorescences, assessment of the rewards available to potential pollinators, and exclusion experiments to establish the effects of various visitors on fruit-set. The flowers are visited mainly by birds and insects. The likely pollinators of G. robusta are sunbirds (Nectarinia amethystina, N. cyanolaema, N. olivacea, N. superba and N. venusta) and white-eyes (Zosterops kikuyuensis and Z. senegalensis). Very little aggressive behaviour between birds was recorded. No nocturnal pollinators were observed. Nectar was the major floral reward for pollinators, but is likely depleted by ants and honey bees, the foraging behaviour of which confirmed them to be nectar-robbers. These insects hardly ever touched stigmas during their visits. Eighty-nine per cent of bird visits were in the morning (07.00–10.00 hours) when nectar volume was highest. Inflorescences bagged to exclude birds set no fruits, and unmanipulated flowers and flowers bagged with self-pollen set no fruits, indicating a self-incompatibility mechanism. Control cross-pollinated flowers displayed greatly increased fruit-set (25.1%) compared with natural open-pollination (0.9%). All these findings confirm the importance of cross-pollen transfer to flowers and the necessity of pollinators for fruit-set. Effective seed production requires activity of pollinators for self-pollen removal and cross-pollen deposition. Seed production stands for G. robusta should be established where flowering is prolific and bird pollinators are abundant.
Insects attacking the seeds of Sesbania species of economic importance in southern Africa
The genus Sesbania (Leguminosae) consists of many species used widely in the tropics for their nitrogen-fixing properties to improve crop production. Most of the perennial species provide animal fodder, fuel wood, fibres, paper pulp and commercial gum, while some (e.g. Sesbania exaltata (Raf.) Cory and Sesbania punicea (Cav.) Benth.) are known to be noxious weeds (Vogt & Cordo 1976; Evans & Rotar 1987).
Agroforestry tree seed production: production guidelines for seed orchards
Community-based forestry and agroforestry programs around the world reforest denuded lands, protect valuable watersheds and produce indispensable tree products for soil improvement and fodder. These programs begin planting operations with a commodity of small size but great importance-seed! Adequate supplies of high quality seed are necessary to grow high quality seedlings. Unfortunately, shortages of seeds are common and limit the success of many community-based tree planting programs. Any discussion about tree seed production must consider the saying “garbage in garbage out”. If you plant junk seeds you will inevitably harvest junk trees.
Seed orchard production guidelines and protocol – notes for farmers
Green manure production systems for Asian ricelands
Progress in adapting green manures (GMs) to Asia’s changing rice production
systems has been limited. Recent research has concentrated on the soil fertility
implications of GMs neglecting the socioeconomic and agronomic aspects that
ultimately determine the feasibility and cost effectiveness of GM systems. Recogni
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tion holistic evaluation and extrapolation of areas where GMs have a comparative
advantage over mineral fertilizer or other nonrice crops are needed. This paper
reviews the strategy for including GMs in rice farming systems and develops a
framework for analyzing the fit of soil
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improving legumes across a range of ecological
niches. Macroeconomic factors such as oil prices and national policy set the
general framework. Other important factors determining the specific adaptation of
GMs are the socioeconomic environment farm
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level economic and biophysical
conditions and availability of appropriate GM species and production technology.
The prognosis for soil
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improving legumes is seen to follow two key possibilities:
1) multiple
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use solutions where the GM also provides grain fodder or fuel; and
2) specificity of GMs to well
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defined niches within the cropping system. Agronomic
research in the hitherto neglected areas of species improvement seed production
crop establishment and pest management may expand the options for GMs in all
niches. The complexity and scale of the work require an international research effort
that provides leadership stimulates coordinated work and involves sharing priority
responsibilities among participating research institutions.