Response of Jatropha on a Clay Soil to Different Concentrations of Micronutrients

In recent years Jatropha curcas L. has emerged as a biofuel crop with potential for its production in marginal land with application of treated sewage water. Since this is a new crop for its profitable cultivation, additional research is needed to develop optimal management programs, including macro and micronutrients applications. A pot experiment was conducted in a Greenhouse at the National Research Center, Dokki, Cairo, Egypt, during 2010 summer to evaluate effects of varying concentrations of iron (Fe), manganese (Mn), and zinc (Zn) in irrigation water (0, 50, 100, 150, 200 and 250 ppm) on the growth, biomass production, photosynthetic pigments, and mineral nutrients status in the plants. Increasing concentrations of Fe, Mn, and Zn in irrigation water up to 150 ppm increased the biomass weight, photosynthetic pigments, and nutrient uptake by Jatropha plants. Further increase in concentrations of micronutrients showed negative effects on the above response parameters. Therefore, this study demonstrates that Jatropha can be grown under irrigation using waste water containing reasonable concentrations of micronutrients and heavy metals. This property of Jatropha provides some support for potential use of this crop for phytoremediation of metal contaminated soils. However, long term field research is needed to further verify both the above beneficial effects.

Effects of Zinc and Ascorbic Acid Application on the Growth and Photosynthetic Pigments of Millet Plants Grown under Different Salinity

Salinity stress impacts crop growth as well as production. The need for increased food production to feed the increasing population and the limited resources, i.e. optimal quality land and water, require developing strategies to mitigate marginal stresses, including salinity stress, for reasonable expectation of crop production. A pot experiment was conducted in a greenhouse at the National Research Centre, Dokki, Cairo, Egypt in the summer season of 2005 to evaluate the effects of foliar application of ascorbic acid alone or in combination with zinc sulfate on the growth and photosynthetic pigments of millet plants irrigated by tap water (250 ppm, 0.39 dS·m-1) or moderate to high salinity irrigation water [2500 ppm (3.9 dS·m-1) and 5000 ppm (7.8 dS·m-1)]. Increased salinity in the irrigation water decreased the plant growth, biomass, and carotenoid content. Foliar application of ascorbic acid alone increased number of leaves and leaf area, while in combination with zinc sulfate increased the plant height and total plant biomass. However, these treatments had no significant effects on the photosynthetic pigments. This study demonstrates that exogenous application of ascorbic acid can enhance foliar growth which may contribute to increased plant biomass and yield.

Pepper plants growth, yield, photosynthetic pigments, and total phenols as affected by foliar application of potassium under different salinity irrigation water

Irrigation with high salinity water influences plant growth, production of photosynthetic pigments and total phenols, leading to reduction in crop yield and quality. The objective of this study was to investigate the effects of potassium (K) foliar application in mitigating the negative effects of salt stress on pepper plants. A greenhouse experiment was conducted to investigate the effects of foliar application of potassium (K) on pepper plants grown with different salinity water irrigation (3000 and 6000 ppm as compared to tap water with salinity level of 300 ppm). Irrigation using high salinity water decreased plant height, biomass production, and fruit yield as compared to those of the plants irrigated by tap water. Photosynthetic pigments and total phenols increased in the former as compared to those of the latter plants. The most serious affect was for the plants under highest salinity irrigation (6000 ppm) as compared to that of the plants under moderate salinity irrigation (3000 ppm). Foliar application of potassium mono phosphate (KMP) at 200ppm concentration increased the plant growth, biomass production, and fruit yield. Chlorophyll_a content and total phenols increased significantly with foliar application of 100 ppm KMP. Further increase in foliar KMP concentration to 200 ppm had no significant benefits on photosynthetic pigments and total phenols content. This study demonstrated that foliar application of KMP, to some extent, mitigated the negative effects of high salinity water irrigation on pepper plant growth and fruit yield.