Papa Saliou Sarr

Effects of phosphite, a reduced form of phosphate, on the growth and phosphorus nutrition of spinach (Spinacia oleracea L.)

Abstract Phosphite (Phi) may potentially supply phosphorus (P) nutrition to plants and is widely marketed as a super P fertilizer for many crops. This study investigated the effects of Phi on growth and P nutrition in spinach (Spinacia oleracea L.). High-rate foliar application experiments designed to evaluate the phytotoxicity and P nutritional potential of different Phi formulations by foliar application at two rates (0.15 and 0.3% P2O5) showed that all Phi formulations did not improve plant growth under different available P-soils, but rather significantly decreased shoot dry weight (DW) at the higher rate. In two other soil and hydroponic experiments, Phi was foliar applied at a low rate (0.05% P2O5) and root P treatments were combinations of Phi and phosphate (Pi) at different Pi : Phi ratios for a high P level (the soil experiment) or a low P level (the hydroponic experiment). In both experiments, shoot DW decreased markedly as the Pi : Phi ratios decreased from 100:0 to 0:100 and Phi foliar application did not improve plant growth. In the soil experiment, plants grew poorest at 0:100, but grew well when both Phi and Pi were applied at a high rate of 115 mg P pot−1, indicating that at this level Phi had a negative effect on only severely P-deficient plants. Root growth of no Pi-fertilized plants was strongly inhibited by Phi from either root or foliar application. In both experiments, P concentration drastically decreased with decreasing Pi : Phi ratios from 100:0 to 0:100, but increased substantially with foliar application of Phi compared with Pi, suggesting that Phi was absorbed poorly by the roots, but was well absorbed by the leaves compared to Pi. We conclude that Phi cannot be used as a P fertilizer for spinach via either root or foliar applications at low or high levels, and also that Phi has no beneficial effect on the growth of spinach. As Phi is now widely marketed as a P fertilizer for many crops, care should be taken in selecting Phi as a P fertilizer for a given crop.

Phylogenetic diversity of indigenous cowpea bradyrhizobia from soils in Japan based on sequence analysis of the 16S-23S rRNA internal transcribed spacer (ITS) region.

Cowpea [Vigna unguiculata (L.) Walp.] is an important legume crop and yet its rhizobia have not been well characterized in many areas. In the present study, sequence analysis of the bacterial 16S-23S rRNA internal transcribed spacer (ITS) region was performed to characterize genetically 76 indigenous cowpea rhizobia from five different geographic regions (Okinawa, Miyazaki, Kyoto, Fukushima and Hokkaido) of Japan. The sequence analysis clustered all isolates in the genus Bradyrhizobium. They were conspecific with B. japonicum, B. yuanmingense, B. elkanii and Bradyrhizobium sp., although none of them grouped with B. liaoningense, B. canariense, B. betae or B. iriomotense. B. yuanmingense was only isolated from the southern region (Okinawa) where it achieved the highest frequency of 69%. B. japonicum was predominant at Miyazaki, Fukushima and Hokkaido with more than 60% of the isolates. B. elkanii was mainly recorded in the southern (Okinawa: 31%, Miyazaki: 33%) and middle (Kyoto: 33%) regions. This species was present at a very low frequency in Fukushima and absent in Hokkaido in the northern area. Bradyrhizobium sp. like-strains were absent in the southern part (Okinawa, Miyazaki) but were concentrated either in the middle regions with 67% of Kyoto isolates and 28% of Fukushima isolates, and in the northern region with 40% of the Hokkaido isolates. This study revealed a geographical distribution of cowpea bradyrhizobia which seemed to be related to the differences in the environmental characteristics (soil type and soil pH, temperature, climate, moisture) of the different regions in Japan.

Biochemical composition and nutritional value of Balanites aegyptiaca (L.) Del fruit pulps from Northern Ferlo in Senegal

Balanites aegyptiaca , a forest species of socio-economic interest for rural people, was chosen to be planted in the frame-work of the Great Green Wall project in Senegal. Although in vastly demand during food scarcity period before crops harvest, the species’ fruit is poorly valued despite its important production. In this study, the fruit pulps were harvested at maturity and the biochemical characteristics were accessed in order to better understand the fruit’s nutritional value. The moisture, sugars, proteins, amino acids, ash, fat, minerals and some vitamins were determined by standard methods of analysis. The results indicated that the fruits are a good alimentary source of sugar, minerals (mainly potassium) and ascorbic acid. The pulp proteins were qualitatively balanced, but were present only in weak quantities. Its caloric value is high due to the high concentration of sugars. Low humidity should allow a fairly good postharvest fruit conservation. The dietary intake of this fruit for local people is very valuable especially in terms of nutrition. Keywords: Balanites aegyptiaca , pulp, biochemical, nutritional value African Journal of Biotechnology , Vol. 13(2), pp. 336-342, 8 January, 2014

Effect of pearl millet–cowpea cropping systems on nitrogen recovery, nitrogen use efficiency and biological fixation using the 15N tracer technique

Abstract Nitrogen is one of the most limiting nutrients for crop production in many areas of Africa. One strategy to improve yields is to choose crops with high nitrogen use efficiency (NUE) that can produce economic yields under limited water supply. Little information is available on the comparative performance of pearl millet (Pennisetum glaucum L. R. Br.) and cowpea (Vigna unguiculata L. Walp.) in sole crops and intercrops systems for the NUE of applied fertilizers. This study was conducted under field conditions at the Senegal Agricultural Research Institute from July to October 2001. Two cropping systems were used and included sole crops of pearl millet and cowpea and a millet–cowpea intercrop. 15N-labeled urea at rates of 20 kg ha−1 (sole and intercrop cowpea) and 41 kg ha−1 (sole millet and intercrop millet) was applied. Sole millet produced 6,041 kg yield ha−1 and accumulated 95.27 kg N ha−1, of which 15.30% was derived from the nitrogen fertilizer and 84.70% from nitrogen mineralized in soil. Therefore, the NUE of the fertilizer was 36.29%. In intercrop millet, sole cowpea and intercrop cowpea, the NUEs were 15.20, 45.33 and 46.00%, respectively, indicating that the use of nitrogen fertilizer significantly decreased in intercrop only for millet. However, no significant difference was observed between sole and intercrop cowpea relative to the nitrogen derived from N2 fixation. The amount of nitrogen immobilized in the soil was significantly higher in sole millet than in sole cowpea and millet–cowpea intercrop. The Land Equivalent Ratio (LER) of grains and total dry matter showed an advantage of the millet–cowpea cropping system over sole crops.

Effects of Organic-Manure Application on Growth, Grain Yield, and Nitrogen, Phosphorus, and Potassium Recoveries of Rice Variety Manawthuka in Paddy Soils of Differing Fertility

A 2-year pot experiment (2005–2006) was conducted in a greenhouse using rice variety Manawthuka on high-fertility Kasuya soil and low-fertility Futsukaichi soil. Fermented cow manure (CM) and poultry manure (PM) were applied as organic nitrogen (N) sources. In every manure application, 20 kg urea ha–1 was also applied at basal. Dry matter, grain yield, and nitrogen uptake were greater in PM than CM and significantly greater in Kasuya soil. In 2006, they increased in Futsukaichi soil but decreased in Kasuya soil. Apparent nitrogen recovery was greater in PM than in CM and increased in both soils in 2006 because of residual benefits from manure application. The apparent phosphorus recovery was greater in CM than in PM; however, large plant phosphorus accumulation was observed in PM. In both soils, the efficiency of CM is very low, and CM-only application is unlikely to achieve an optimal rice yield in the short term.

Cassava value chain development through partnership and stakeholders' platform in Cameroon

1International Institute of Tropical Agriculture (IITA) Burundi office, BP 1893, Bujumbura. 2International Institute of Tropical Agriculture (IITA), Humid Forest Ecoregional Center, BP 2008 Messa, Yaounde, Cameroon. 3Graduate School of Asian and African Area Studies, Kyoto University, Japan. 4Programme National de Developpement des Racines et Tubercules (PNDRT) Cameroun. 5AVRDC/The World Vegetable Center, Samanko Research Station, BP 320, Bamako, Mali.

INTERACTIONS BETWEEN CASSAVA VARIETIES AND SOIL CHARACTERISTICS IN CROP PRODUCTION IN EASTERN CAMEROON

Cassava represents a staple food source in Cameroon and in many other tropical countries, as it is effectively able to combat hunger. This study was carried out to: (i) determine the growth characteristics of improved and local cassava varieties in Eastern Cameroon under repeated cultivation, (ii) assess the effects of different soils on cassava growth, and (iii) dis- seminate the improved varieties throughout the region. The experiment was carried out during the 2010-2011 and 2011-2012 seasons. Two improved varieties, TMS-92/0326 and TMS- 96/1414, and the local Ntolo variety were cultivated at three sites in a randomized block design with six replications. No fertilizer was applied and the fields were weeded regularly. A two- way ANOVA (variety x site) for each season showed that variety and site were equally signifi- cant, and there were no significant interactions between varieties and sites. The improved va- rieties had higher yields (2.0-5.5-fold higher) than Ntolo, with cassava mosaic disease having seriously affected the Ntolo yield. Soil acidity and organic matter content in the soil surface horizon may be major factors affecting the cassava yield, with TMS-92/0326 and Ntolo being tolerant of higher acidity than TMS-96/1414, which suggests that variety-soil interactions should be considered when improved varieties are introduced.