Performance of Leucaena leucocephala, Seedlings in Two Agro-climatic Regions of Kenya

A study was conducted to determine the response of Leucaena seedlings planted in two variant agro-climatic regions, Chepkoilel Campus and Maseno in Kenya. The experiment was a 2-factor (provenance – site) split plot design with five replications. Three provenances were randomly assigned to the sub-plots. A block measuring 60 m by 30 m was divided into two plots, which were separated by a 1 m strip of land. The study was conducted at Chepkoilel College Campus and Maseno farms in Kenya. Farm experiments were conducted. Soil samples were amended with lime at the rate of 6.6 ton/ha. Three genotypes of Leucaena were planted. At 60 DAP and 120 DAP, seedlings were subjected to analysis to determine seedling height, root length, root collar diameter, leaf number and seedling biomass at both sites. There was variation in the performance of each provenance based on the growth parameters assessed between the two sites. KIT2724 recorded the highest means in all growth attributes followed by K136, and the lowest means was recorded by K156 at Maseno. However, in Chepkoilel, K136 recorded the best performance in the growth Original Research Article Kodiango et al.; JAERI, 6(4): 1-7, 2016; Article no.JAERI.234892 attributes followed by KIT2724 and lastly by K156. L. leucocephala provenances (K136) seedling growing in the field at Chepkoilel bore flowers and pods at the age of 6 months. The seedlings of L. leucocephala grew faster at Maseno than at Chepkoilel. With liming, KIT2724 and K136 could be grown in acid soils especially in both Maseno and Uasin Gishu Districts where agroforestry practice is being promoted. However, K156 seems to be more tolerant to soil acidity and the genetic basis of this tolerance should be further established

Response of Leucaena leucocephala (Lam.) De Wit (Leucaena) Provenances to Aluminium in Potted Soil Experiment

Aims: To determine the level of acid or aluminium tolerance provenances in Leucaena (Leucaena leucocephala) a favourite agroforestry tree in Kenya. Study Design: The set up was a 2-factor (provenance-aluminium) experiment in a completely randomized design with three (3) replications and data were subjected to multivariate analysis of variance. Place and Duration of Study: Potted acid soil experiments were carried out at the Maseno ICRAF/KEFRI centre and Chepkoilel campus farm, Moi University, between June 2009 and July 2010. Methodology: Potted acid soil experiments were carried out at the Maseno ICRAF/KEFRI centre (pH 4.8) and Chepkoilel campus farm, Moi University (pH 5.0) to assess the effect of varying aluminium concentrations on growth of three local leucaena provenances: K156 (Gede), K136 (Kibwezi) and KIT2724 (Kitale). Aluminium was applied at 0, 100, 200 and 300 M. The number of leaves per seedling, seedling height, root length, root collar diameter and dry weight were recorded at 60 and 120 days after planting. Results: Generally Aluminium at 100 M significantly (p0.05) enhanced growth of the seedlings at both sites. However, aluminium at 200 M reduced seedling growth. Conclusion: The Leucaena provenance K156 could be used in acid soils because it is tolerant. However, more local provenances should be screened for acid tolerance

Genetic Diversity in Cultivated Sesame (Sesamum indicum L.)

Genetic diversity of traditional sesame landraces and related wild species in East Africa remains largely unexplored. Knowing what fraction of the available genetic diversity is actually used by the farmers is of central importance for understanding how cultiva- tion shapes the genetic structure of a crop and for the management of biodiversity preservation. Genetic diversity in cultivated sesame and related wild species in East Africa was determined using inter-simple sequence repeats (ISSR). Six reliable ISSR primers generated 51 amplification fragments of which 36 (70.6%) were polymorphic. The number of amplified fragments ranged from 7 to 12 with a mean of 8.5 fragments per primer. The overall gene diversity and Shannon’s index were 0.28 and 0.34, respectively. Jaccard’s similarity coefficient ranged from 0.26 to 0.96, with an average of 0.67. Forty-six accessions of sesame were divided into six clusters, although the clustering did not indicate any clear division among sesame accessions based on their origin. Each wild species was more distant from cultivated sesame than from other wild species, indicating that no cross-pollination with wild species occurred during sesame domestication. These results showed a relatively high genetic diversity in sesame and related wild species. Indian-1 and Indian-2 accessions showed a good amount of genetic divergence. The genetic diversity data uncovered in this study can be exploited to improve traditional landraces of sesame in East Africa

Molecular markers associated with aluminium tolerance in Sorghum bicolor

Background: Sorghum (Sorghum bicolor, L. Moench) production in many agro-ecologies is constrained by a variety of stresses, including high levels of aluminium (Al) commonly found in acid soils. Therefore, for such soils, growing Al tolerant cultivars is imperative for high productivity. Methods: In this study, molecular markers associated with Al tolerance were identified using a mapping population developed by crossing two contrasting genotypes for this trait. Results: Four SSR (Xtxp34, Sb5_236, Sb6_34, and Sb6_342), one STS (CTG29_3b) and three ISSR (811_1400, 835_200 and 884_200) markers produced alleles that showed significant association with Al tolerance. CTG29_3b, 811_1400, Xtxp34 and Sb5_236 are located on chromosome 3 with the first two markers located close to AltSB, a locus that underlie the Al tolerance gene (SbMATE) implying that their association with Al tolerance is due to their linkage to this gene. Although CTG29_3b and 811_1400 are located closer to AltSB, Xtxp34 and Sb5_236 explained higher phenotypic variance of Al tolerance indices. Markers 835_200, 884_200, Sb6_34 and Sb6_342 are located on different chromosomes, which implies the presence of several genes involved in Al tolerance in addition to SbMATE in sorghum. Conclusion: These molecular markers have a high potential for use in breeding for Al tolerance in sorghum. Keywords: Aluminium tolerance, Mapping population, Molecular markers, Net root length in aluminium, Sorghum bicolo

Cell membrane integrity, callose accumulation, and root growth in aluminum-stressed sorghum seedlings

Aluminum stress usually reduces plant root growth due to the accumulation of Al in specific zones of the root apex. The objectives of this study were to determine the localization of Al in the root apex of Sorghum bicolor (L.) Moech. and its effects on membrane integrity, callose accumulation, and root growth in selected cultivars. Seedlings were grown in a nutrient solution containing 0, 27, or 39 μM Al3+ for 24, 48, and 120 h. The Al stress significantly reduced root growth, especially after 48 and 120 h of exposure. A higher Al accumulation, determined by fluorescence microscopy after staining with a Morin dye, occurred in the root extension zone of the sensitive cultivar than in the tolerant cultivar. The membrane damage and callose accumulation were also higher in the sensitive than resistant cultivar. It was concluded that the Al stress significantly reduced root growth through the accumulation of Al in the root extension zone, callose accumulation, and impairment of plasma membrane integrity

Enhancing Maize Grain Yield in Acid Soils of Western Kenya Using Aluminium Tolerant Germplasm

Abstract: Maize (Zea mays L.) is one of the world’s most important cereals and is a staple food for many people in developing countries. However, in acid soils (pH < 5.5), its productivity is limited by aluminium (Al) toxicity, besides other factors. The objectives of this study were to: develop Al tolerant maize inbred lines for a maize breeding program in Kenya, develop single cross hybrids (SCHs) from some of the tolerant inbred lines and determine Al tolerance levels of the SCHs. One hundred and seventy five inbreds and 49 SCHs were developed and screened in nutrient culture containing 0 or 222 μM using Relative Net Root Growth (RNRG), hematoxylin staining (HS) and under Al saturated field conditions (44%-45.6%) at Sega and Chepkoilel. Seedling root growth was inhibited in 95% of the inbreds. F1 hybrids obtained from inbreds varying in Al tolerance, exhibited tolerance equal to or greater than that of the more tolerant parent indicating a positive transgressive inheritance to Al toxicity. Fifty eight percent of the F1 SCHs were heterotic for tolerance to Al toxicity. Al tolerance estimated by RNRG was well correlated to that of HS (r2 = 0.88, P < 0.005) but minimally correlated with the field estimates (r2 = 0.24-0.35), implying that RNRG can predict field selection under Al toxic soils by between 24% and 35%. Plant breeders should therefore employ both approaches in selecting cultivars under Al stress. This study has developed and identified Al tolerant inbreds and SCHs for use in the acid soils of Kenya and similar regions

Development of maize single cross hybrids for tolerance to low phosphorus

Low available phosphorus (P) is one of the major hindrances to maize (Zea mays L.) productivity in acid soils. The objectives of this study were to: (1) develop P-efficient maize inbred lines, (2) develop single cross hybrids from the P-efficient inbred lines, and (3) determine their response to P application in the P-deficient acid soils of western Kenya. Ninety-eight inbred lines and 49 single crosses were developed and screened at P-deficient (2.0 to 2.2 mg P/kg soil) soils of Sega and Bumala. Mean grain yield (GY) for the hybrids was 75.3% higher with P-fertilizer than without P for the same hybrids. Thirty-three percent (33%) of these hybrids were inefficient but responsive to P application, 27% were efficient and none responsive, only 13% were efficient and responsive, while the rest were inefficient and non-responsive. GY was positively correlated (r = 0.57**) with plant height (PH) and ear height (EH) (r = 0.60**) and PH was correlated with EH (r = 0.86***). This study has developed and identified P-efficient maize germplasm that can be utilized directly or in developing other hybrids for use in acid soils of western Kenya and in other acid soils where P is limiting

Phosphorus Sorption and Lime Requirements of Maize Growing Acid Soils of Kenya

In Kenya, maize (Zea mays L.) is mainly grown on acid soils in high rainfall areas. These soils are known for low available phosphorus (P), partly due to its sorption by aluminium (Al) and iron oxides. The study determined soil P sorption, lime requirements and the effects of lime on soil pH, Al levels and available P on the main maize growing acids soils in the highlands east and west of Rift Valley (RV), Kenya. Burnt lime containing 21% calcium oxide was used. The soils were strongly to extremely acid (pH 4.85-4.07), had high exchangeable Al3+ (> 2 cmol Al kg-1) and Al saturation (> 20% Al), which most maize germplasm grown in Kenya are sensitive to. The base cations, cation exchange capacity and available P (< 10 mg P kg-1 bicarbonate extractable P) were low, except at one site in the highlands east of RV indicative with history of high fertilizer applications. Highlands east of RV soils had higher P sorption (343-402 mg P kg-1) than the west (107-258 mg P kg-1), probably because of their high Al3+ ions and also the energies of bonding between the soil colloids and phosphate ions. Highlands east of RV also had higher lime requirements (11.4-21.9 tons lime ha-1) than the west (5.3-9.8 tons lime ha-1). Due to differences in soil acidity, Al levels and P sorption capacities within and between highlands east and west of RV, blanket P fertilizer and lime recommendations may not serve all soils equally well. Keywords: acid soils, phosphorus sorption, lime requirement

Effects of lime, phosphorus and rhizobia on Sesbania sesban performance in a Western Kenyan acid soil

Aluminium (Al) toxicity, phosphorus (P) deficiency and low rhizobia populations limit Sesbania (Sesbania sesban) performance in tropical acid soils. The study determined the i) indigenous rhizobia populations that nodulate sesbania and ii) effects of lime (0 and 4 t/ha), P-fertilizer (0 and 60 kg/ha) and acid tolerant rhizobia (0 and inoculation) on soil and selected sesbania accessions performance in Western Kenya acid soil. Study site had acid soil, low available P, nitrogen (N) and rhizobia populations that nodulate Sesbania (146 cells/g soil). Lime increased soil pH, while both lime and P-fertilizer increased available P. Aluminium toxicity tolerant and P-efficient accessions (SSBSA004, SSUG3, SSUG4 and SSUG5) had faster growth, higher nodulation, shoot P, and shoot N and response to treatments than the sensitive one (SSBSA203). After 7 months of growth, SSUG3 had highest shoot length (306 cm) and dry matter (5.64 tons/ha), hence, most suitable for building poles and fuel wood. SSUG5 accumulated the highest shoot N (222 kg N/ha) and was therefore, most suitable soil N replenishment. Thus, in acid P deficient and low rhizobial population soils of Western Kenya, the use of lime, P-fertilizer, rhizobia inoculation and Al toxicity tolerant Sesbania are important for Sesbania establishment and growth. Key words: Rhizobia, Sesbania, soil acidity, aluminum toxicity, lime, phosphorus