Effect of irradiance on growth, physiological processes and yield of melon (Cucumis mela) plants grown in hydroponics

The effect of different irradiance levels on melon (Cucumis mela) cv. Birdie, Charity Ball and Jade Dew grown in hydroponics was investigated. Plants were exposed to mean daily irradiance levels of 11.4,8.2, 6.1 and 3.0 MJ m-2 day-1 achieved by using different levels of shade. The dry matteryield appeared to be directly proportional to the irradiance level received by plants. Stomatal conductance and photosynthetic rate were highest when the plants were grown under the highest irradiance level. Plants grown under 11.4 MJ m-2aI had the highest fruit fresh weight and total soluble solids. All cultivars failed to fruit when grown under irradiance of 3.0 MJ m-2aI

Effect of N and K fertilizers on nutrient leaching and groundwater quality under oil palm

The major nutrients required for oil palm are mainly nitrogen, phosphorus and potassium. When applying fertilizers to the palms, our goal is to maximize nutrient uptake by the palms from the fertilizers for optimum growth and production. Unfortunately, losses of applied fertilizer to the atmosphere or through runoff and leaching generally occur as unintended consequences of fertilization. One of major pathway of fertilizer losses is by leaching in which nutrients are moved down the soil profile until they reach a depth where there are no palm roots. Consequently this can be of serious environmental concern in areas where nutrients can enter groundwater. Nitrogen and potassium are the most nutrients at risk, because of the rather weak adsorption of ammonium and potassium ions and nil adsorption for nitrate (Corley and Tinker, 2007). It has been reported that leaching losses for a clay loam soil under mature palm were about 2-6% of the applied N and K fertilizers and 1-3% for P fertilizer (Foong, 1993)

Impact of water resources availability on agricultural sustainability in the Gavkhuni river basin, Iran

One of the most interesting water management case studies in Iran is the case of Zayandehrud River, the main river that supplies water to Isfahan Province which is located in Gavkhuni River Basin (GRB). This paper examines the present and future demands for water and determines the extent to which water will be available for agricultural use by the year 2020. Although demand and supply conditions in 2000 were more or less in balance, there was an increase in the supply of some 28% by 2010 due to the completion of the third trans-basin diversion and the development of other local water sources. However, the demand exceeded its supply in 2010 and the basin fell into severe deficit. In this condition, the only way to keep supply and demand in balance is to reduce allocations to agriculture. By 2020, agriculture would only have 5% more water than the present and water supply is only 90% that of the normal, and this would then shrink from 2025 onwards. In other words, agriculture would have to be sacrificed in order to ensure full supplies of water for the other sectors. The scenarios examined reveal that a sustainable agriculture can only be accomplished by water saving practices and management measures, which may further lead to reduced demand, control supplies, and improve the efficiency of water use

Water Quality Profile of Sg. Langat

This study was conducted between August and December 1985 in order to assess polluting effects from different landuse patterns. Nine sampling sites were chosen over a distance of 60 km. A number of physical and chemical parameters were analysed. Statistical tests and Water Quality Index were used to evaluate the water quality variation. The result shows that relatively high BOD, suspended solids, electrical conductivity and turbidity occurred after Hulu Langat town. The statistical test indicated that the water quality variation is significantly different (p < 0.05); the Water Quality Index shows that the water quality near Kajang town has deteriorated compared to other stations