Salt stress induced damages on the photosynthesis of physic nut young plants

Salinity is a major limiting factor to crop productivity in the world especially in semiarid regions. The aim of this study was to evaluate the photosynthetic resistance of Jatropha curcas (L.) young plants subjected to salt stress. The experiment was carried out in a completely randomized design with treatments in a 2 x 3 factorial: two NaCl levels (0 and 100 mmol L-1) and three harvest times: 7 and 14 days of salt exposure and three days of recovery. Leaf Na+ and Cl-concentrations and the K+/Na+ ratios, after seven days of salt exposure, did not reach ionic toxic levels, suggesting that the NaCl-induced osmotic effects prevailed over the ionic ones. Under this condition, the salt stress caused reduction in leaf gas exchange parameters, such as CO2 fixation, stomatal conductance and transpiration. In contrast, salt stress did not change the photochemical efficiency of photossystem II. Conversely, after 14 days of treatment, Na+ and Clions reached very high concentrations, up to toxic levels in leaves. Under such conditions, both leaf gas exchange and photochemistry suffered strong impairment probably caused by ionic toxicity. The recovery treatment for 3d did not significantly decrease the leaf salt concentrations and no improvement was observed in the photosynthetic performance. Physic nut young plants are sensitive to high NaCl-salinity conditions, with high leaf Na+ and Cl- concentrations, low K+/Na+ ratio and great photosynthetic damages due to stomatal and biochemical limitations.A salinidade é um dos principais fatores que limitam a produtividade das culturas no mundo principalmente em regiões semiáridas. Avaliou-se a resistência da fotossíntese de plantas jovens de pinhãomanso (Jatropha curcas L.) submetidas ao estresse salino. O experimento foi realizado em delineamento inteiramente casualizado com tratamentos em fatorial 2 x 3: duas concentrações de NaCl (0 e 100 mmol L-1) e três tempos de avaliação (7 e 14 dias de exposição e três dias de recuperação). As concentrações de Na+ e Cl- e a relação K+/Na+ nas folhas, após sete dias de exposição ao sal, não indicaram níveis tóxicos, sugerindo os efeitos osmóticos induzidos pelo NaCl prevaleceram sobre as causas iônicas. Sob essas condições, o estresse salino causou redução nos parâmetros de trocas gasosas, como fixação de CO2, condutância estomática e transpiração, mas ao contrário, não alterou a eficiência fotoquímica do fotossistema II. Após 14 dias de tratamento, os íons salinos atingiram concentrações muito elevadas nas folhas, provavelmente atingindo níveis tóxicos. Em tais condições, as trocas gasosas e a atividade fotoquímica sofreram forte redução causada pelo estresse iônico. O tratamento de recuperação não induziu queda intensa nas concentrações dos íons salinos nas folhas e nenhuma melhoria foi observada no desempenho fotossintético. Plantas jovens de pinhão manso são sensíveis a condições de salinidade elevada por NaCl, mostrando altas concentrações de Na+ e Cl-, baixa razão K+/Na+ e danos fotossintéticos intensos causados tanto por limitações estomáticas como por limitações bioquímicas

Potential of adopting bamboo as an alternative crop to tobacco farming in South Nyanza region, Kenya : a paper presented at the WHO-FCTC Second Meeting of the Study Group on Economically Sustainable Alternatives to Tobacco Growing Mexico City, 17-19 June 2008

Objective: To experiment the potential of adopting bamboo as an alternative crop or source of livelihood to tobacco farming in South Nyanza region, Kenya. // Design: The study is being carried out on 120 field experimental sites where 2451 bamboo seedlings were planted between September and October 2006. The experiment comprised of 1,208 giant bamboo (Dendrocalamus giganteus) and 1,243 common bamboo (Bambusa vulgaris). Each seedling was planted in a cubical hole measuring 0.5m x 0.5m x 0.5m. The seedlings were planted under the same natural tobacco growing conditions in five different zones (i.e. zone A = hillside/steep sloping farmland, B = hillside/gentle sloping farmland, C = flat farmland/not wetland/ river bank, D = flat farmland/wetland and E = homestead) based on each farmer’s preference. Half of the bamboo clumps were randomly selected and tagged for monitoring. Hence, at most, 5 plants of each species were selected from the 20 planted by each farmer. The parameters which were monitored in the twelve months were: survival rates, number of culms, culm heights and culm diameter. Literature review was conducted to have a detailed understanding of activities in the bamboo and tobacco industries in Kenya and other parts of the world. Data analyses were done using SPSS and Excel computer packages. Frequency tabulation and bar graphs were used to present the data. // Results: The study revealed that the two species of bamboo perform well in gentle slopes and flat farmlands but not on wetlands. A part from the wetlands, survival rates of Bambusa vulgaris and giant species was ranging between 69% and 94%. It also emerged that Bambusa vulgaris bamboo establishes faster than giant species and withstands water logging than giant species. The findings show that the two species of bamboo can do well in soil and agro-climatic conditions similar to those of tobacco. The study has further revealed that most of the bamboo products sold in the formal retail market in Kenya are imported, a scenario that results in high market prices and low demand for the products. It also emerged that besides numerous economic advantages of bamboo, social and environmental problems associated with tobacco farming can be reduced through bamboo production. Furthermore, skills and structures used by tobacco farmers in the tobacco industry can effectively be used in bamboo processing. // Conclusions and Recommendations: Giant and Bambusa vulgaris species of bamboo require similar natural conditions of production as tobacco. From the production point of view, the two species of bamboo can do better in soil and agro-climatic conditions favourable to tobacco growing. Tobacco processing skills and structures can also be used in the bamboo industry with minimal shifting capital investment. It is recommended that for the shifting from tobacco to bamboo in this region, the farmers must be well trained on bamboo processing at the community level, market should be well structured and more bamboo species introduced in the region because of their diversified uses. There is also need to encourage domestic production of the high quality bamboo products to save foreign exchange. To replace tobacco with bamboo in Kenya, the current experiment needs to be replicated in the other 10 remaining tobacco growing areas in the country. Capacity building will be very important through training and farmers empowerment in bamboo production and processing

Potential of bamboo as an alternative crop and livelihood strategy to smallholder tobacco farmers in South Nyanza region, Kenya

PowerPoint presentationThe presentation reviews successful crop diversification of 120 farm trial sites in Kenya, where bamboo seedlings were planted under the same growing conditions as tobacco crops in terms of soil, altitude, rainfall and temperatures. The presentation compares the cultivation of tobacco and bamboo in terms of inputs/outputs and costs/benefits. Bamboo cultivation and training was provided. 50% of former tobacco farmers involved in the project have switched to bamboo, which can be used for housing, furniture, handicrafts and general construction. Recommendations include provision of a transitional fund to support input requirements as well as to cover the period when intercropping with bamboo is completed

Growth performance of bamboo in tobacco-growing regions in South Nyanza, Kenya

Due to copyright restrictions, this item cannot be sharedThe study was carried out in 120 field experimentation sites where 2420 bamboo cuttings were planted under the same tobacco-growing conditions in five different zones. Each farmer was given 20 bamboo cuttings: 10 each of giant bamboo (Dendrocalamus giganteus) and common bamboo (Bambusa vulgaris). Findings show that the two species can grow well in soil and agro-climatic conditions similar to those of tobacco. To replace tobacco with bamboo in Kenya, the experiment needs to be replicated in remaining tobacco-growing regions in the country. Capacity building through farmer empowerment, training, and in bamboo processing will be important

Fotossíntese e acúmulo de solutos em feijoeiro caupi submetido à salinidade

O objetivo deste trabalho foi determinar as respostas fotossintéticas e a acumulação de carboidratos, íons salinos e prolina em feijoeiro caupi (Vigna unguiculata) submetido à salinidade. As plantas foram submetidas à quatro tratamentos, dos 28 aos 35 dias de idade: 0, 50, 100 e 200 mmol L-1 de NaCl. Avaliaramse as trocas gasosas, a emissão de fluorescência pela clorofila a, o potencial hídrico foliar, e as concentrações de carboidratos, Na+, Cl- e prolina nas folhas. Os tratamentos não tiveram efeito sobre a eficiência quântica potencial do fotossistema II, mas causaram leve diminuição na eficiência quântica efetiva e maior dissipação do excesso de energia de excitação por processos não fotoquímicos. As concentrações foliares de amido diminuíram, e as de sacarose e prolina aumentaram nas maiores concentrações de NaCl. Ocorreu exclusão do Na+ e acúmulo do Cl- nas folhas, e as relações hídricas das folhas foram pouco afetadas, exceto no tratamento mais severo. O acúmulo de Cl- esteve envolvido na redução da assimilação de CO2, decorrente da queda na condutância estomática e na eficiência de carboxilação da Rubisco. O feijoeiro caupi apresenta características fisiológicas que favorecem a manutenção da atividade fotossintética sob curta exposição à salinidade