The mangrove belt along the coast of the three Guianas, South America, forms a unique ecosystem and acts efficiently as a natural soft coastal defence structure. The general mechanisms have been studied for over four decades and the processes governing the coastal morphodynamics are now understood, at least qualitatively. They consist of an interaction between mangroves, hydrodynamics and sediment mechanics. 20% of the mud discharged by the Amazon in the Atlantic Ocean is transported to the west along the coast by waves and currents in discrete mud banks of a few 10s of km length which travel at a speed of the order of 2 km/year. During the presence of a mud bank waves are damped, mud is trapped and colonized by mangroves. Once a mud bank has passed, the waves can attack the shore again. This results in a cycle of land accretion and erosion, with an average net gain of 1 m coast per cycle of roughly 30 years. However, in locations where too many mangroves have been removed, the coast has lost its natural resilience and the settlements and fields are prone to flooding, a concern that increases with climate change and predicted sea level rise (SLR). Hard coastal defence structures, such as those in Guyana, are expensive and not sustainable. Based on many lessons learnt, pilot projects on mangrove rehabilitation have started. At the same time research efforts are undertaken to allow making quantitative estimates of the potential risks for the coastal communities. For this purpose, numerical prediction models are developed which can compute currents, wave action and sediment transport along the coast of the Guianas. Different climate change scenarios can be investigated. These models can serve in the near future as decision support tool for the local authorities for the management of the coastal zone.

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Present research was carried out during the year 2014-2015 at the National Agricultural Research and Extension Institute (NAREI) to determine the effect of vermicompost and other fertilizers on the growth and productivity of pepper plants (Capsicum chinense). Plants were treated with five different treatments, namely T 1 (Promix), T 2 (vermicompost), T 3 (189), T 4 (189 + vermicompost), and lastly, control which had no fertilizers. T 1 , T 3 , and T 4 were inorganic fertilizers, and T 2 was organic. Results obtained showed that T 3 (chemical fertilizer) has a significant effect on the growth of pepper plants producing plants with better plant height, number of leaves, number of branches, stem diameter, higher fruit yield, fruit weight and fruit diameter. Plants treated with this treatment also had higher fruit yield, fruit weight, and fruit diameter. Mineral nutrients were highest in plants treated with inorganic fertilizers as compared to the organic fertilizer. Maximum chlorophyll level was present in plants treated with T 2. There were relatively high levels of pest and diseases in plants treated with chemical fertilizers, delayed flowering and fruiting period and high levels of leaf and fruit abscission as compared to plants treated with organic fertilizer (T2). Moreover, T 3 has proven to have a greater effect on the growth parameters of pepper plants but not the quality of plants produce.

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This study was conducted at two sites in Mississippi to determine whether petiole and leaf NO -3 monitoring could be used as a management tool in making fertilizer N recommendations for sunflower (Hellanthus annuus L.). Petiole and leaf samples were taken at the four leaf stage at both sites, and later at two week intervals at Brooksville. Petiole and leaf NO -3 at the four leaf stage was significantly influenced by rate of N application at both sites. The level of petiole and leaf NO -3 was highly correlated with rate of N application as well as with seed yield. The concentration of NO -3 in petioles and leaves was greatest at the four leaf stage and showed quadratic declines as the season progressed. Petiole and leaf NO3 showed the highest correlations with rate of N application and seed yield at the four leaf stage than at any other sampling time at Brooksville, indicating that this was the "best" period for taking petiole and leaf samples. However, analysis of petioles and leaves at 1257

The yield performance of cowpea var. Minica # 4 (Vigna unguiculata L.) on an Arenic Paleudult (Acrisol) was evaluated in an alley cropping experiment with Gliricidia sepium (Jacq.) Kunth ex Walp., Leucaena leucocephala (Lam.) de Wit and a treeless control during a short- (November-December 2004), and long-(May-June 2005) rainy season at Ebini, Guyana. The alley cropping treatments had no significant effect on cowpea plant height, pods per plant, pod weight per plant and grain weight. During the short-rainy season, values for cowpea plant height and number of pods per plant were higher compared to those for the long-rainy season, and number of pods per plant was positively correlated with pod weight. During the long-rainy season, pod weight and grain weight were correspondingly higher. Plant height vs. number of pods per plant; number of pods per plant vs. pod weight; and, number of pods per plant vs. grain weight, were all positively correlated. Cowpea could yield the same or more when associated with managed fast growing, nitrogen (N)-fixing trees or treeless plots. This alley cropping practice has the potential to reduce the use of fossil-fuel generated fertilizers and reduce the potential production of an important greenhouse gas (GHG).