Effect of subsequent storage of tuberose (Polianthes tuberosa L.) bulbs after low temperature pre - treatment improves growth, percent sprouting and cut flower quality

During peak planting time in commercial tuberose cut flower production lack of seed materials occasionally occur. Most producers also source planting materials which have not been adequately stored resulting in poor performance of the crop. For improved productivity in tuberose cut flower value chain, ways of increasing the availability of planting materials and improving the growth performance need attention. This study examined the effects of subsequent warm temperature storage after low temperature treatment of tuberose bulbs on growth, sprouting and flower quality. The experiment was laid in a split plot arrangement in a completely randomized design. Tuberose bulbs were stored in a biotron at 5ºC or 10ºC for 3 months with subsequent temperature storage of 20ºC for 0, 2, 4 or 6 weeks. The main effects were pre‐treatment temperatures at 5 or 10ºC, whilst subsequent temperature storage treatments constituted the sub‐effects. Days to sprouting were significantly earlier ( 14.9) when tuberose bulbs were pretreated at 10ºC followed by 20ºC subsequent temperature storage for 6 weeks compared to 51.1 at 5ºC pretreatment with no subsequent temperature storage. The highest percent sprouting (99.2%) was obtained with 10ºC pretreatment followed by 20ºC thawing for 6 weeks. Pre‐treating tuberose bulbs at either 5ºC or 10ºC then planting directly resulted in 69.3% and 88.3% sprouting, respectively, whilst similar pretreatments resulted in 70.0% and 81.2% flowering. The number of days to flowering were significantly (P<0.05 ) reduced (110.8) at 10ºC pre‐treatment followed by 20ºC subsequent thawing for 6 weeks compared to 143.1 at 5ºC pretreatment with no thawing respectively. Stem length of inflorescences significantly (P<0.05) improved to 106.8 cm at 10ºC with thawing at 20ºC for 6 weeks compared to 98.2 cm at 5ºC pretreatment and no thawing respectively. Number of florets per spike also significantly (P<0.05) increased to 42.4 compared to 34.9 for similar treatments. Storage of tuberose bulbs at low temperatures followed by warm subsequent storage for 2, 4 or 6 weeks besides improving sprouting and quality of flowers could enhance the availability of planting materials for crop production. The planting materials could be bulked with possibility of commercial exploitation.Key words: Flower quality, growth, low temperature storage, sprouting, tuberosebulb

Characterization of methomyl and carbofuran degrading-bacteria from soils of horticultural farms in Rift Valley and Central Kenya

The use of pesticides is very critical in protecting the farmers’ investment in seeds, fertilizer and labour since they provide a sure cover from damage by pests. The use of pesticides is therefore inevitable and the environmental pollution due to pesticides and their residues will continue to be a challenge. In this study, bacterial strains capable of degrading methomyl (S-methyl-N-[(methylcarbamoyl) oxy]-thioacetimidate) and carbofuran (2, 3-dihydro-2, 2-dimethyl-7-benzofuranyl methylcarbamate) were isolated from soils sampled from horticultural farms with a history of pesticide usage. High pressure liquid chromatography was used to monitor biodegradation of both methomyl and carbofuran using reference standards and acetonitrile and water as mobile phases. Partial 16S rDNA sequence analysis indicated that the carbofuran-degrading strains were closely related to members of the genus Pseudomonas and Alcaligenes while the methomyl degrading strains were closely related to members of the genus Flavobacterium and Alcaligenes. The morphological and biochemical characteristics of the isolates also confirmed the phylogenetic signature. The study established that the activities of the esterase and phosphatase enzymes correlated well with biodegradative capability and recommends possible application of the isolates in the in vivo bioremediation of pesticide contaminated soils.Key words: Pesticides, carbofuran, methomyl, biodegradation, bacteria

Effect of Gibberrellic Acid on Growth and Fruit Yield of Greenhouse-Grown Cape Gooseberry

Cape gooseberry is wildly grown in most parts of the tropics. A study was conducted to establish the optimal concentration and the critical stage of application of gibberellic acid (GA3) in promoting plant growth and fruit yield in Cape gooseberry. GA3 concentration of 100 ppm, and 12.5 pp, were applied at one week after transplanting, at flower initiation, and at fruiting stages, respectively. A 5 x 3 x 3 factorial experiment was designed and data collected on number of plant branches, plant height, and number of the fruits on a weekly basis for the whole economic life of the plant. Data was then analysed by GenStat statistical program where least significant difference (LSD) was used to separate and compare the means at 5% level of significance. Application of GA3 increased branching, flower bud formation and fruiting. The higher the concentration the greater was the growth and yield. However, applying GA3 at 100ppm one week after transplanting the seedlings resulted in plants producing significantly largest number of fruits (303 fruits per plant), number of branches (20 branches per plant), and plant height (112.4 cm)

The effect of Rootstocks on Bud-take and Bud Growth Vigour of Rose (Rosa spp) Cultivar ‘First Red\'

A rootstock trial was conducted at Jomo Kenyatta University of Agriculture and Technology, Juja (Latitude 1o 05´ S; longitude 37o 01´ E) to investigate the success of the rootstock-scion combination and the vigour of the sprouted bud. Three rootstocks, namely Rosa multiflora, Rosa indica ‘Major\', and Rosa canina ‘Inermis\', were budded with scions of rose cultivar ‘First Red\' Bud union success significantly greater in R. indica ‘Major\' (90%) than in R. multiflora (77.8%), and R. canina ‘Inermis\' (55%), respectively. As the number of days from date of budding increased, significant differences were observed on growth performance of scion shoots. At 42 days, there were no significant differences in growth vigour of R. multiflora and R. indica ‘Major\' but both rootstocks were significantly different from R. canina ‘Inermis\'. At 63 days, R. multiflora had significantly longer stems than R. indica ‘Major\' and R. canina ‘Inermis\'. The number of harvested flowers per plant was significantly higher in R. multiflora than in R. canina ‘Major\' and R. canina ‘Inermis\'. The stem diameter and percent marketable blooms did not differ significantly in the various bud combinations. No significant differences were observed in the stem length in R. multiflora and R. indica ‘Major\', but R. canina ‘Inermis\' was significantly shorter. The number of days to first flower was significantly greater in R. canina ‘Inermis\' than for R. indica ‘Major\' and for R. multiflora. Journal of Agriculture, Science and Technology Vol.3(2) 2001: 57-6

Factors influencing in vitro shoot regeneration of Macadamia integrifolia

study was carried out to investigate the effect of culture medium factors that influence the shoot regenerative potential of Macadamia nodal segments in vitro. Explants were obtained from shoots ofcurrent growth flush of Macadamia integrifolia and inoculated onto different test media. Woody plant medium (WPM) gave results comparable to MS medium whose macronutrients had been reduced to half rate. Explants cultured on media gelled with Biotec agar No. 1 and Purified agar had significantly higher bud breaking frequency and shoot number per explant than Phytagel and Gelrite. Optimum cultureperformance was obtained on MS medium enriched with 30 g/L sucrose. Highest bud breaking frequency (98%), shoot number per explant (8.1) and shoot length (3.3 cm) were obtained when WPM was supplemented with 2 mg/L BAP, 1 mg/L IBA and 1 mg/L GA3. When elongated shoots were cultured on to medium supplemented with cytokinins for rooting, only excessive callusing was obtained but no roots were formed within the culture period. The results of this study indicate that M. integrifolia is amenable to tissue culture but further studies are required to obtain rooting of in vitro shoots to come up with an optimized commercially feasible protocol for Macadamia tissue culture