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Abstract
CHAPTER 1
INTRODUCTION
Maize (Zea mays L.) is one of the most important cereal crops, in Egypt and the world. The area devoted to maize cultivation in Egypt is about 1.70* million feddan in 2008 season and average yield/feddan reached 25.7 ardab/fed. Maize in the world ranks the third surpassed only by wheat and rice. It is widely used in bread making in rural areas of the country because it conforms the basis for several industries such as starch, fructose, corn flakes, alcohol, corn oil, corn sugar, corn fiber (soronoa), ethanol and biobutanal as well as the main component (about 70%) of animal feed in Egypt, it is necessary to increase maize yield to face the wide gab between the production and consumption. High maize production can be achieved by improving cultural practices and planting the promising hybrids. Corn agronomists continually research for methods that help them increase grain yield and net return of producing the crop.
Phosphorus is one of the major nutrients limiting plant growth. Although bound P is quite abundant in many soils, it is largely unavailable for plant uptake. Crop yield on 40% of the world’s arable land is limited by P availability. As currently practiced, agriculture with require 55 – 60 106 Mt of P fertilizer applied to agricultural soils to meet food production needs in 2040 (FAO. 2003). However, P is not a renewable resource and its future use in agriculture will be impacted by declining availability and increasing cost. Moreover the striking increase in the use of fertilizers by intensive agriculture practices has led to degradation of air and water quality. Therefore, sustainable management of P in agriculture requires strategies to enhance its acquisition uptake by plants. In this context, the most realistic solution according to Marschner (1995) is the use of Arbuscular mycorrhizae (AM) that have the ability to acquire P and give high yield under limited P supply.
Arbuscular mycorrhizae (AM) fungi develop a hyphal network that serves as a fundamental link between the soil, the nutrient reservoir, and the plant. This hyphal network is more efficient for ion uptake than root hairs (Dorneless et al., 2001). Arbuscular mycorrhizae can also provide many non-nutritional benefits to crops, including alleviation of water (Allen and Boosalis, 1983). Arbuscular mycorrhizae is the most enceinte and widespread type of mycorrhizae symbiosis. Phosphorus uptake and growth of host plants are stimulated by AM fungi. In return host plants provide carbohydrates for their fungal planters (Smith and Read, 1997).
Sulphur application, as a soil amendment, is a common agricultural practice in Egypt especially in the new reclaimed lands and became very important in the last few years. Several studies have shown the positive advantages of sulphur application to soils to enhance the solubility and availability of phosphorus and some micronutrients to plants, dissolving native lime in calcareous soils, controlling some fungal diseases, decreasing high pH values of alkaline clay and calcareous soils as a result of sulphuric acid formation and it also plays a good role in regulating urea transformation in soils.
Therefore, the objectives of this study were to investigate the response of maize to phosphorus fertilization, mycorrhizae inoculation and sulphur application as a soil amendment under salt affected soils.