Maize (Zea mays L.), the most cultivated cereal in the world, is the staple food in Africa and in developing countries [1] . This is one of the major grains produced in the humid tropics of sub-Saharan Africa. It is a universal culture placed third after wheat and rice in world production [2] . In Benin, maize occupies almost 82% of the total area under cereals and represents about 84% of cereal production. The national maize production increased from 782,974 tons in 1999 to 1,205,200 tons in 2009, an increase of 35% in a decade [3] . As such, any action in favor of this speculation can help to lay the foundations for sustainable food security.

Benin has a diverse range of corn varieties with improved varieties developed by international research institutes, and local varieties managed by peasants and farmers themselves [4] . These traditional and local cultivars are the most cultured and most used cultivars at the expense of different types of selected varieties (hybrids, composites, etc.). Indeed, during the 2009-2010 campaign, traditional and local cultivars accounted for 63%, or 759,926 tons of the total volume produced estimated at 1,205,200 tons despite the availability of improved varieties developed by researchers [5] . Improved varieties have better agronomic performance than local and traditional varieties. However, despite their superior agronomic performance, improved maize varieties developed by research are very few adopted and therefore little cultivated by peasants because of their requirements for specific inputs and their technological and organoleptic qualities which still meet users’ needs [6] [7] . This situation persists because of the extra work and expense entailed [8] , and their ability to withstand biotic and abiotic stresses [9] . However, farmers’ seeds are generally considered by agronomists as resources with limited potential, with a share of responsibility for the low productivity of traditional agricultural systems [10] . This is due to the widespread adoption of traditional varieties with low production potential. Indeed, in traditional agriculture, local varieties constitute the bulk of the plant material used [11] . Thus, one of the main constraints to increase maize production in Benin is that the yield is low. To contribute to the improvement in yields, it is necessary to lift this constraint by the development of improved varieties with high yield potential adapted to the needs of producers. So to solve the increasingly food demand, modern agriculture is more developed and focused not only to select performing varieties but also to the diversification of cultivars in seed system [12] . The introduction of high- yielding varieties depends mostly on access to local genetic resources. These local resources are indeed an essential component of food security as they provide the raw material used by breeders to improve the quality and productivity of corn [13] .

Thus, a prospecting mission and collection was organized in 2013 in all departments of the Centre and North of Benin. The inventory and agro-morphological characterization of these genetic resources are therefore essential to generate a solid database on the characteristics of the Central and Northern Benin maize collection, for the new varieties creation to meet the producers’ expectations. This agro-morphological characterization requires the use of certain evaluation techniques using morphological markers [14] . Such studies have already been carried out on grains such as maize [13] [15] , the sorghum [16] , rice [17] [18] , millet [19] [20] , the barley [21] and wheat [22] [23] . The overall objective of this study was to evaluate the genetic variability within the maize collection at the Centre and North of Benin by using morphological descriptors.

Knowledge of the genetic diversity of plant genetic resources in plant breeding is essential [27] . For a good knowledge of this genetic diversity must be performed prior morphological study. So there are many techniques to quantify and analyze the genetic diversity at multiple levels of biological organization. Which include the evaluation techniques using morphological markers [28] . Morphological analysis (Botany) then constitutes a first genetic diversity assessment approach.

Analysis of the morphological diversity of maize accessions collected in central and northern Benin has revealed a large variation in quantitative variables. The parameters plant height, ear height, tassel length showed a large variation (˃10%) while variable female flowering, male flowering, days to ear leaf senescence and germination days showed small variation (˂10%) in both zones except in the North the germination days presented a

large variation. This variation shows diversity among maize accessions grown in central and northern Benin. In studies conducted by N’da et al. [27] in Ivory Coast on the morphological characterization of maize observed a wide variation of agronomic traits such as plant height and ear height (˃10%) and a low coefficient of variation (˂10%) for the tassel length, male and female flowering. Unlike our results, N’da et al. [13] observed a small variation (˂10%) of plant height of local maize accessions in Ivory Coast. This difference can be explained due to the exclusive use of local maize accessions in Ivory Coast but also the difference in the origin of these accessions and also the type of soil.

A positive correlation was found between plant height and ear height at the accessions of Benin Centre. And more plant height increases, the ear height is great. The same observation was made by Kim and Hallauer [29] who noticed a fairly strong positive correlation between plant height and ear height in maize. This result is very important in a breeding program that interest in a variety of high ears height and less vulnerable to pest.

The numerical classification revealed four groups of accessions morphological similarity perspective both at the Centre and the North of Benin. In both areas the four groups are discriminated by the earliness, characters related to plant and ear height. The work of N’da et al. [13] in Ivory Coast has shown that earliness, heights

Proportions with the same letters on the same line are not significantly different. Legend: m = means; cv = coefficiant variation.

characters, and cob parameters contribute to discriminate corn accessions. Similarly, these characters have been used to describe the variability of maize varieties grown Cuzalapa populations in Mexico by Louette and Smale [30] . According N’da et al. [27] peasant phenotypic selection based on visible characters (phenology, vegetative, ear) could explain the contribution of these variables to the structuring of variability. The importance of semi- flowering period in the differentiation of accessions is due to the fact that all the descriptors involved in the distinction are related to this descriptor. Moreover, the husk cover and sensitivity to streak discriminate Centre accessions unlike North accessions that are discriminated by the germinal parameters and maturity cobs. This difference can be explained by the difference in climate prevailing between the two different areas. The groups obtained at the Centre and North of Benin are heterogeneous in terms of status and origin of accessions. Thus in each cluster it has been observed a mixture of local and improved accessions. Similarly, there was not a grouping accession from the same locality. This could be explained by the exchange of varieties that occur among peasants from different localities. Indeed, several authors have shown that peasant seed management practices, including exchange of varieties among farmers are the cause of a significant diversity between populations of crop plants [11] [31] .

Preliminary results on the morphological diversity of corn grown in the Centre and North of Benin showed that the studied accessions presented a variation for all characters used. Thus, a significant difference was found among all accessions for each agro-morphological characteristics evaluated with the exception of the germination days for accessions of the Centre; the tassel length and germination days for accessions of Northern Benin. Significant differences were recorded between the minimum and maximum values of the variables under study. This diversity has been structured into four groups for Centre and North Benin accessions. The characters which are the most distinctive among accessions of the Centre are those related to the precocity, the height of plant and ear, husk cover and sensitivity to streak. For the North accessions, the most discriminating agro-morphological characteristics are based on the germinal parameter, precocity, maturity of cobs and variables related to the plant and ear height. Each group has got in its interesting characters in maize breeding in Benin. The morpho-genetic variability among accessions is then given a real base for future breeding work. For a complete characterization of these accessions it will be important to perform a molecular characterization.

The authors thank the students and technicians who participated in the making and taking of data on various tests for their collaboration. This study was funded by the West Africa Agricultural Productivity Program (WAAPP).

Hafiz A. Salami,Adolphe Adjanohoun,Wilfrid Padonou,Abdoul-Madjidou Yacoubou,Djima Aly,Chabi Yallou,Haziz Sina,Lamine Baba-Moussa, (2015) Morphological Diversity of Corn’s (Zea mays L.) Local Cultivar and Improved Varieties in Central and North of Benin. American Journal of Plant Sciences,06,2867-2877. doi: 10.4236/ajps.2015.618284