Comparison of maize hybrids effect on phenological stages

Introduction

Maize is an important multi-purpose crop used for food, fodder, chemicals and biofuels. According to the FAO, total world maize production reached 6.37×1012 tons (http://nue.okstate.edu/ Crop Information/) in 2003, higher than wheat or rice. In developing countries such as China, a huge demand for maize is expected due to the increase in animal production and biofuel requirements. Yield increase in maize is largely due to larger nitrogen (N) fertilizer inputs (Dai, 1998).

Maize (Zea mays L.), is a cereal with a remarkable potential for production, it is the third most important grain crop after wheat and rice and it accounts for 4.8% of the total cropped land area and 3.5% of the value of agricultural output (Ahmad et al., 2011). Maize due to capabilities such as adaptation to different climatic conditions (from 58 degrees to 4 degrees south and north from sea level to an altitude of 4000 m), Resistance to drought, high performance, power, frequency of exposure, accept full mechanization and usage of several widely cultivated in many countries. Corn addition to being very good forage for livestock is also unique in terms of energy supply for livestock and poultry.

Large variation was observed for all the characters studied except days to flowering, days to maturity and protein content. Correlation and path coefficient analyses showed that biological yield and harvest index were the major direct contributors to seed yield. The 100-seed weight, plant height, days to flowering and maturity, canopy width, and protein content contributed to seed yield mainly through indirect effect via biological yield and harvest index. The 100-seed weight and seed yield were major contributors to biological yield. Major contributor to protein content was days to maturity (Sing et al., 1990). Determination of importance and effectiveness of yield components is main target. Besides, relationship between yield characters and yield may change in various trials and agronomical and breeding programs. Determining and processing effective yield components and relationships between them causes significant yield increase and leads better results. Chand et al., (1975), Katiyar et al., (1977), İslam & Begüm (1985), Malik et al., ( 1988), Khan et al., ( 1989) and Gravaes & Helms (1992) reported that grain yield had positive relationship with plant height, number of branches, number of pods per plant and 100 seed mass.

The genetic diversity of crop species is the result of natural selection on the wild parents and human intervention. The extent and distribution of the genetic diversity in a crop depends on its breeding system, geographical, ecological and human factors. Conservation of genetic variability is essential for present and future human wellbeing (Tiranti 2006). Study of genetic diversity is essential for conservation, management and to identify the hybrids (Franklin 2009). The genetic diversity among and within landraces makes them a valuable resource as potential donors of genes for breeding purposes, diversification of production, developing new farming systems and new quality products (Soleri & Smith 1995, Jing et al. 2010). To develop crop varieties and attain significant progress in breeding programs, it is essential to know the relationship between seed yield and its component (Assady et al. 2005).

Plant density determines the degree of competition among plants (Ipsilandis and Vafias, 2005; Kgasago et al., 2006). Fasoula and Tollenaar (2005) indicated the number of plants per unit area has been significant to assess the conduciveness of seedbed in a microenvironment. Therefore, at low densities, grain yield is limited by number of plants, whilst at higher densities decrease due to competition. An increase in plant density ensures uniform crop stand (Elliot et al., 1993; Tollenaar et al., 1994), and also increase grain yield and water productivity, particularly under rainfall limited regimes (Lamm et al., 2009). However, in semi-arid regions, the risk of crop failure increases as density increases (Jagtap and Chan, 1999). An optimum plant density is which yields the most grain under non-limiting conditions (Modarres et al., 1998). The objective of the present study was to determine the maize hybrids on Performance characteristics.