American-Eurasian J. Agric. & Environ. Sci., 13 (11): 1554-1561, 2013 ISSN 1818-6769 © IDOSI Publications, 2013 DOI: 10.5829/idosi.aejaes.2013.13.11.11254 Corresponding Author: O.J. Olawuyi, Department of Botany, PMB 128 University of Ibadan, Ibadan, Nigeria. 1554 Correlation, Principal Component Analysis and Tolerance of Maize Genotypes to Drought and Diseases in Relation to Growth Traits O.M. Olowe, A.C. Odebode, O.J. Olawuyi and A.O. Akanmu Department of Botany, P.M.B. 128 University of Ibadan, Ibadan, Nigeria Abstract: Six maize genotypes (IBIZA-EN13) TZBR COMP 2-YC S , TZBR COMP 2-YC S 280, AMA TZBR 1 1 1 1 YC F , TZEI 25, TZEI 22 and TZEI 161) were evaluated for their resistance to drought and diseases in an open 1 1 field pot experiment conducted at the Research Farm of the Department of Botany, University of Ibadan, Nigeria. The experiment was laid out in a complete randomized design (CRD) with four replications. The genotypes were subjected to drought stress from 6 to 8 week after planting. Data on growth characters were recorded, while th th the drought and diseases / pest infestations were also scored. Data collected were statistically analyzed using SAS 9.1 statistical package. The genotypes and period of drought experiment were positive and significantly (p<0.001) correlated with the growth characters. Also, the genotypes recorded significant correlation with diseasing severity, although no correlation exists between drought resistance and disease severity. The proportion of spread of the genetic variability of the maize genotypes on growth characters ranged from 37.76% to 9.09%, while the drought and disease assessment varied by 58% to 42% as determined according to Eigen analysis. Maize genotype TZEI 161 showed the best drought tolerance but produced the least vegetative growths. AMA TZBR YC F conferred the highest resistance against diseases and pest infestations (2.29) but 1 1 was not drought tolerant (3.58). However, the maize genotype TZBR COMP 2-YC1S1 280 moderately combined the drought tolerant (2.75) and disease resistant (2.54) traits, it also showed the best vegetative performance. Therefore, TZBR COMP 2-YC1S1 280 is the recommended genotype when drought tolerance and disease resistance traits are desired. Key words: Correlation Disease resistance Drought Genetic variability Maize genotypes Pest infestation INTRODUCTION been reported to cause an estimated reduction of Maize (Zea mays L.) is a versatile crop grown across destruction of the stem bark of the food crops, a common a wide range of agro-ecological zones [1]. It is one of the occurrence at the end of the dry season that leads to most economically important cereals in the world, after alteration in the plant growth and most important wheat and rice with regards to cultivation area, total increased yield loss [8]. production and consumption [2-4]. Maize is high yielding, Maize crop requires about 400 to 600 mm of water easy to process, readily digested and cheaper than other during its lifecycle [9]. This is because plant distribution cereals. In Nigeria, conventional maize is used directly for and yield in crop production are largely determined by animal and human consumption [5,6]. water availability [10]. However, water resources have However, it’s per hectare yield is still very low due to become insufficient due to climate change, population a number of stress factors which includes a complex pest growth and competition from other water users [11]. and diseases that reduces the quantity and quality of Thereby, leading to environmental stresses such as production [7]. Insect pests especially variegated drought, high temperature, salinity, air pollution, heavy grasshopper (Z. variegatus (L) are voracious and metals, pesticides and soil pH which constitute major destructive pest of food crops. Z. variegatus alone had limiting factors in crop production because they affect the 50% in maize yield through leaf defoliation and