A two year study was carried out in two locations in south eastern Nigeria in the years 2008 and 2009, to determine the effect of planting space on plant population at harvest, and corm yield in cocoyam cultivars. This was aimed to identify optimum planting space for optimum cocoyam production. Five taro cultivars; Nkpong, Ugwuta, Nworoko, Odogolo and Nadu were used. Three planting space; 50 x 100 cm, 40 x 100 cm and 30 x 100 cm were tested. The result showed that decreasing planting space from 50 x 100 cm to 40 x 100 cm resulted to increase in plant population at harvest. There was a decline in plant population as planting space was further decreased to 30 x 100 cm. The closest planting space of 30 x 100 cm produced the highest tuber yield ha -1 among the three planting space in the two locations. The result also showed that the Ugwuta cultivar produced the highest tuber yield among the five cultivars in the Nsukka location while the Odogolo cultivar recorded highest tuber yield in the Umudike location. It was therefore recommended that planting at the spacing of 30 x 100 cm should be adopted as a production practice in these areas for high tuber yield in cocoyam.

Mycorrhiza is obtained from two Greek expressions, namely: mykes (fungus) and rhiza (root). In otherwise, mycorrhiza means fungus-root as coined by Frank in 1885. So, mycorrhiza association is defined as the mutual relationship between fungus and plant root in which the fungus derive carbon from its host plant while the host plants obtain minerals from the fungus. Mycorrhizas are found in different biomes ranging from high latitudes and altitudes, deserts, lowland tropical forest to aquatic ecosystems. It is a known fact that several plants cannot thrive in their natural habitats without this mutualism, as 95-99 % of all plant species have been estimated to belong to genera that generally form mycorrhizas. It is only three families of plant that do not enter into mutual relationship with fungus. These families are as follows: Cyperaceae, Chenopodiaceae, and Brassicaceae. There are now seven types of mycorrhizas among which are arbuscular (AM) endomycorrhiza, ericoid endomycorrhizas, arbutoid endomycorrhizas, monotropoid endomycorrhizas, orchidaeous endomycorrhizas, ectomycorhizas and ectendomycorrhizas. The benefits of mycorrhiza association cannot be overemphasized as studies have shown that it improves nutrient supply of carbon, phosphorus and nitrogen to both plant and fungus that might not normally be made available to plant roots in large amount. It also enhances the performance of plant growing in soils with high amounts of heavy metals and water absorption of desert plants.

A research on growth and yield components of some turmeric varieties (Curcuma longa L.) as affected by inorganic fertilizer levels in Umudike, South Eastern Nigeria was carried out at the teaching and research farm of the University, during 2018/2019 cropping seasons. It was laid out in a split plot design with three replications. Results, showed that plant height and number of tillers for both varieties and fertilizers levels increased at 2, 4, and 6 months after planting (MAP) during 2018 and 2019 cropping seasons. Variety 021 and 400 NPK (15:15:15) Kg-1 produced tallest plants and highest number of tillers over other varieties and fertilizer levels. Crop growth rate was positive at 2 – 4 MAP and negative at 4 – 6 MAP, with 021 and 400 NPK (15:15:15) kgha-1 producing higher growth rate. Heaviest rhizomes fresh weight (kg plot-1) of 3.74 and 3.75, rhizome dry matter content of 14.49 and 16.8%, rhizome dry weight of 23.57 and 23.90g and harvest index of 2.60 and 2.70% was yielded by UMT 021 variety over other varieties. The level of 400 NPK (15:15:15) kg ha-1 produced heaviest rhizome fresh weight of 4.47 and 4.57 kg plot-1; rhizome dry matter content of 19.42 and 25.8%; rhizome dry weight of 27.54 and 27.8g and harvest index of 2.81 and 3.20%, over other levels. Consequently, variety 021 and 400 NPK (15:15:15) kgha-1 are recommended for sole production of turmeric in Umudike, South Eastern Nigeria.