Abraham J, Joseph K, Joseph P (2015) Effect of integrated nutrient management on soil quality and growth of Hevea brasiliensis during the immature phase. Rubber Science 28: 159-167.
Adebisi MA, Okelola, FS, Ajala MO, Kehinde TO, Daniel IO, Ajani OO (2013) Evaluation of variations in seed vigour characters of West African rice (Oryza sativa L.) genotypes using multivariate technique. American Journal of Plant Science 4: 56-363.
Alika JE (1991) Principal component analysis of variations pattern among sixteen Hevea clones. Nigerian Journal of Agricultural Science 6: 20-24.
Alle JY, Dick EA, Soumahian EF, Olaye RG, kebi JZ, Obouayea S (2015) Effect of mineral fertilizer on agro physiological parameters and economic viability of clone PB 253 of Heveabrasiliensis in the region of G O in SW. Coted’voire. Journal of Animal and Plant Sciences 24: 3768 – 3780.
AOAC (1990) Official methods of analysis 15thedition.Association of official analytical chemists Washington, D.C. USA.
Aremu CO, Ariyo OJ, Adewale BD (2007) Assessment of selection techniques in genotype x environment interaction in cowpea (Vigna unguiculata L.) Walp. African Journal of Agriculture Research 2: 352 – 355.
Awe OA, Thogong TK, Nze'e SY, Adegboye MA (2007) A survey of soil fertility management technologies used by small holders in Jos Plateau. In: Olufaji OO (Ed), Reviving Agriculture for sustainable natural growth and stable democracy. Proceedings of the 41st Annual Conference of Agricultural society of Nigeria (ASN) held at IAR, Samaru, ABU Zaria, Nigeria 22nd - 26th October, 2007.
Awodun MA, Ojeniyi SO, Adeboye A, Odedina SA (2007) Effect of oil palm bunch refuse ash on soil and plant nutrient composition and yield of maize. American Eurasian Journal of Sustainable Agriculture 1: 50 - 54.
Campbell S (2004) Discriminant analysis of heavy metal concentrations in the soil of St.John’s New found land. Available on http://www.mun.ca/biology/schneider/b4605/GradProj/StacyCampbellProj04.pdf access on 29th April, 2017.
Chauhan JS (2001) Fertility status of soils of Bilra panchayathsamiti of Jodhpur district (Rajasthan). M.Sc. (Ag.) thesis submitted to MPUAT, Udaipur, Rajasthan, India.
Corley RHV, Tinker PB (2009) The Oil palm, 4th Edition. UK Blackwell Science Ltd. Oxford.
Couto EG, CuntaCaitianunes da (2006) Application of Multivariate analysis to identify soil landscapes in the Pantanal of MatoGrosso – Brazil, a poster presentation at the symposium organized by WCSS held in Thailand, 14th – 21st August, 2002.
Damrongrak I, Onthong J, Nilnond C (2015) Effect of fertilizer and dolomite applications on growth and yield of tapping rubber trees. Songklanakarin Journal of Science and Technology 37: 643-650.
Dharmakeerthi RS, Chandrasiri JAS, Edirimanne VU (2012) Effect of rubber wood biochar on nutrition and growth of nursery plants established in an ultisol. Springer plus 1:1-13.
Edokpayi AA, Osayande PE, Ikuenobe CE, Aghimien AE (2015) Multivariate analysis of soils under oil palm cultivation in Nigeria. Nigerian Journal of Agriculture Food and Environment 11: 97-102.
Esekhade TU, Okore IK, Ogidi EGO, Arasowan J (2013) Effect of weeding frequency and fertilizer
rates on the Growth performance and budding successes of Hevea rootstock seedling in a humid forest area of south eastern Nigeria. International Journal of Agriculture and Rural Development16: 1421-1424.
Gouvêa LRL, Rubiano LB, Chioratto AF, Zucchi M, Gonçalves PS (2010) Genetic divergence of rubber tree estimated by multivariate techniques and microsatellite markers. Genetics and Molecular Biology 33: 308-318.
Habibpour M, Ahmadizadeh M, Shahbazi H (2012) Assessment of relationship between agro – morphological traits and grain yield in bread wheat genotypes under drought stress condition. African Journal of Biotechnology 11:8698 – 8704.
Idehen EO, Kehinde OB, Ariyo OJ (2007) Numerical analysis of variation among Nigerian accessions of ‘Egusi’ Melon (Citrullus lanatus (Thunb.) Matsum & Nakai). Journal of American Science 3: 7-15.
ILACO NEDECO (1966) Report on the soil investigations in the Niger Delta special areas. The Hague special areas Aruhem, The Hague, Netherlands.
International Institute of Tropical Agriculture (1979) Laboratory manual for soil and plant analysis. Manual series 7, IITA, Ibadan.
International Rubber Study Group (2012). Rubber Statistical Bulletin 52:7–9.
Ishfaq M, Abbas RM, Nasir IA (2012) Effect of budwood age, budding height and stock looping, on bud take in sweet orange (Citrus sinensis L.) var pine apple. Global Advanced Research Journal of Agricultural Science 1:275-278.
Iwara AI, Ogundele FO, Ibor UW (2011) Multivariate Analysis of Soil – Vegetation Interrelationships in a South – Southern Secondary forest of Nigeria. International Journal of Biology 3: 73 - 82.
Jenkinson DS, Ayanaba A (1977) Decomposition of carbon-14 labeled plant material under tropical conditions. Soil Science Society of American Journal 41: 912–915.
Kamalu OJ, Ugwa IK, Omenihu AA (2014) Survey, classification and suitability evaluation of Akwete soils for rubber (Heveabrasiliensis) cultivation in southeastern Nigeria. Acta Agronomica Nigeriana 14: 56 – 63.
Kavitha C, Sujatha MP (2015) Evaluation of soil fertility status in various agro ecosystems of Thrissur District, Kerala, India. International Journal of Agriculture and Crop Sciences 8: 328-338.
Kumar M, Kumar V, Kumar R, Pratap R (2017) Correlation between soil nutrient and plant nutrient concentration in mustard. Journal of Pharmacognosy and Phytochemistry 6: 751 – 754.
Marschner H (1997) Mineral nutrition of higher plants, Academic Press, San Diego.Pp. 889.
Miller PA, Williams JC, Robinson HF, Comstoc RE (1958) Estimates of genotypic and environmental variances and covariance in upland cotton and their implications in selection. Agronomy Journal 50: 126 – 131.
Mohammadi SA, Prasanna BM (2003) Analysis of genetic diversity in crop plants salient statistical tools and considerations. Crop Science 43:1235-1248.
NageswaraRao DVK, Jose AL (2002) Numerical classification of soils under rubber in Kerala. Journal of Indian Society Soil Science 50: 492 – 497.
Nassir A (2002) Studies on genotype x environment interactions, variability and plant character correlation in rice. PhD thesis submitted to the Postgraduate school of University of Agriculture, Abeokuta, Nigeria Pp. 123.
Nwofia GE, Awaraka R, Mbah EU (2014) Yield and yield component assessment of some African
yam bean genotypes (Sphenostylis stenorcarpa Hochst Ex A. Rich) Harm in low land humid tropics of south eastern Nigeria. American- Eurasian Journal Agricultural and Environmental Sciences 14: 923-931.
Okore IK, Akpobome FA, Tijani-Eniola H, Oghide EA (2007) Effect of tillage on the growth performance of Hevea seedling rootstock and some fertility indices of sandy acid soil in the humid forest area of Nigeria. Journal of Rubber Research 10: 116-126.
Okore IK, Idubor C, Ogidi EGO, Okundia RO (2016) Latex and dry rubber yield response of a natural rubber clone to stimulation and fertilizer application in a sandy-loam ultisol. Proceedings of the 3rd National Annual of Conference of crop Society of Nigeria, held at UNN, Nigeria on 27th-39th September, 2016 Pp. 496-503.
Oku E, Iwara A, Ekukinam E (2012) Effects of age of rubber (Hevea brasiliensis Muell Arg.) plantationon pH, organic carbon, organic matter, nitrogen and micronutrient status of ultisols in the humid forest zone of Nigeria. Kasetsart Journal Natural Science 46: 684-693.
Omokhafe KO, AliKa JE (2000) Multivariate of agronomic data on Heveabrasiliensis. In: NoKoe S (Ed). Biometry and quality of life. Proceedings of SUSAN – IBS meeting, 23rd27thAugust, 1999, Ibadan, Nigeria, SUSAN – IBS, Nairobi, Kenya, Pp. 168 – 173.
Osayande PE, Oviasogie PO, Awanlemhen BE, Orhue ER (2014) Soil fertility assessment of a Shea (Vitellaria paradoxa Gaertn C. F.) field at Bida, Niger, State. Nigerian Journal of Soil Science 24:117-124.
Raji AA (2002) Assessment of genetic diversity and heterotic relationship in African improved and local cassava (Manihot esculentus Crantz) germplasm. PhD thesis submitted to the Postgraduate school, University of Ibadan, Nigeria.
Samish RM, Gur A (1962) Experiments with budding avocado. Proceedings of the American Society for Horticultural Science 81:194-201.
SAS Institute Inc. (1996) SAS software: Changes and enhancements through release, 6.12. Cary: SAS Institute Inc.
Snedecor GW, Cochran WG (1980) Statistical methods (Ed. 7). The Iowa State University Press, Ames, Iowa, U.S.A. Pp. 507.
SPSS (2004) SPSS for windows version (16.0) software programme.
Suchartgul S, Maneepong S, Issarakrisila M (2012) Establishment of standard values for nutrient diagnosis in soil and leaves of immature rubber tree. Rubber Thai Journal 1: 19-31.
Tisdale SL, Nelson WL, Beaton JD (1993) Soil Fertility and Fertilizers, 5th Edition, Macmillan Publishing Co., New York U.S.A.
Tolentino LM (2010) Mykovam as a promising organic fertilizer on the growth of rubber (Heveabrasiliensis) seedlings at USM, Kabacan, Cotabato, Philippines. USM R and D Journal18: 125-128
Waizah Y, Giroh YD, OjieKpon F, Umar H, Oghide A (2011) Influence of rubber effluent on some soil chemical properties and early growth of rubber seedling. Proceedings of the 45thAnnual Conference of Agricultural Society of Nigeria, held at UDUS, Nigeria on 24th – 28th October, 2011 Pp. 469-477.
Wiley EO (1981) Phylogenetics: Theory and Practice of Phylogenetics and Systematics. John Wiley, New York U.S.A.
Yada B, Tuamuhabwa P, Alajo A, Mwanga ROM (2010) Morphological characterization of Ugandan sweet potatogermplasm. Crop Science 50: 2364-2371.