Rootstock growth and development for increased graft success of mango (Mangifera indica) in the nursery

The graft success of seedlings depends on rootstock size and the skills of grafters. A study was carried out to evaluate the effects of rootstock diameter (at root collar), skills and experience of grafters on mango seedling thinning and grafting. Skilled and unskilled grafters were involved in grafting mango plants for at least three consecutive months. Different rootstock sizes based on root collar diameter of mango seedlings were assessed. The results showed significant differences in graft-take among three groups of nurserymen. The skills and experience of grafters had a significant effect on graft success. The late emerging seedlings showed higher increase in height and diameter after thinning. A higher survival (> 75%) and reduced time to graft-take (19 days) were achieved with thicker rootstocks (0.7 cm) than thinner rootstocks (0.3 cm). The early emerging plants produced more leaves than late emerging plants after grafted. It was concluded that a higher graft-take can best be achieved with skilled grafters and thicker rootstocks

Effective preconditioning methods for in vitro propagation of Uapaca kirkiana Müell Arg. tree species

The objective of the study was to determine efficient preconditioning methods for in vitro multiplication of Uapaca kirkiana plant materials from mature stock plants. The efficacy of sodium hypochlorite(NaOCl), calcium hypochlorite {Ca(OCl2)2} or mercuric chloride (HgCl2) as surface sterilant was evaluated in decontaminating explants excised from grafted and field-collected U. kirkiana trees.Different Murashige and Skoog (MS) medium supplements were evaluated for shoot multiplication and root regeneration. Results indicated that preconditioning grafted U. kirkiana trees before excisingexplants and decontaminating explants in 0.1% w/v HgCl2 were effective methods in establishing aseptic cultures (80%). Lateral shoots (new shoots) responded positively to shoot multiplication on ¾strength MS medium supplemented with a combination of 0.1 mg/L benzylaminopurine, 0.04 mg/L naphthaleneacetic acid and 0.3 mg/L casein hydrolysate. High concentrations of thidiazuron (>0.1 mg/L)suppressed bud break. Rooting (36%) was achieved with ½ MS medium supplemented with 2.5 mg/L indole-3-butyric acid. Plantlets were successfully hardened off. In vitro multiplication of mature U.kirkiana plant materials was achieved using lateral shoots excised from grafted U. kirkiana trees after preconditioning with fungicides

Water application rate and frequency affect seedling survival and growth of Vangueria infausta and Persea americana

Adequate amount of water is critical to successful tree nursery operation among resource-constrained smallholder farmers in Africa. Two  experiments were undertaken with the objectives of evaluating effects of water application rate and frequency on seedling growth and survival of Persea americana and Vangueria infausta. In experiment 1, water was applied to seedlings at 500 ml per 1 L polyethylene bag daily and at two, four and six day intervals. In experiment 2, water was applied to seedlings every two days at the rate of 25, 50, 100 and 150 ml per polyethylene bag. The results indicated that V. infausta was more responsive to the rate than frequency of water application. Water application of 100 ml every two days was effective in promoting seedlings growth and survival for both species. Application of 500 ml of water every two days promoted growth of P. americana, while watering frequency had no significant effect on V. infausta. It is concluded that V. infausta seedlings require less frequent watering. Both species could be successfully raised with 100 ml of water applied every two days.Key words: Nursery irrigation, nutrient reserves, root collar diameter, seedling mortality

A decision support tool for propagating Miombo indigenous fruit trees of southern Africa

Indigenous fruit trees (IFTs) contribute to the livelihoods of rural households as sources of food, income and medicine. Conservation and domestication of IFTs involve germplasm selection, collection,multiplication and evaluation. In addition, biodiversity and genetic improvements have been realized through propagation. However, there are numerous challenges when propagating indigenous trees andthe choice of appropriate propagation techniques determines the success of domestication programme. In this paper we synthesize different propagation methods used for indigenous fruit trees,and propose a decision support tool based on desirable attributes of individual IFT, technical requirements, expertise of the propagators and relative cost of implementing the technology in addition to field performance and tree management. Depending on circumstances, this decision support tool can be used to quickly choose a propagation method for a given fruit tree so as to maximize on germplasm collection, multiplication and evaluation without compromising field performance and management of the fruit trees

Effect of growing medium on early growth and survival of Uapaca kirkiana Müell Arg. seedlings in Malawi

The use of appropriate growing medium has been an important factor influencing growth and survival of seedlings in the nursery. Raising Uapaca kirkiana rootstocks from seeds has been a challenge aspencil-size stem thickness is required before grafting can be done. An experiment was carried out with the objective of determining an effective growing medium that ensures survival and rapid growth of U.kirkiana seedlings. Ten different combinations of sand, forest soil and sawdust amended with four different levels of nitrogen, phosphorus and potash fertilizer were evaluated. The result showed that thegrowing medium comprising 75% forest soil and 25% sawdust produced the tallest seedlings with larger root collar diameter and higher survival at ten months after planting. Amending the samegrowing medium with fertilizer improved the root collar diameter of the seedlings. It is concluded that a growing medium comprising 75% forest soil and 25% sawdust and amended with NPK fertilizer wassuperior in improving U. kirkiana seedling growth to attain a suitable diameter for grafting within ten months