The livestock species play very important economic and socio-cultural roles for the wellbeing of rural households, such as food supply, source of income, asset saving, source of employment, soil fertility, livelihoods, transport, agricultural traction, agricultural diversification and sustainable agricultural production. The aim of this work was to identify and characterize the different roles that livestock and livestock species play in rural communities of Timor-Leste, highlighting the importance of animal production for the wellbeing and rural development, and relate the functions performed by livestock production with economic, social and cultural attributes of the communities. The data used in this study were collected in 2011 through a questionnaire survey in three rural communities in the district of Bobonaro, namely in a mountain area, an irrigation plain and a coastal zone, and were complemented with secondary data. Livestock production in Timor-Leste is predominantly familiar being chickens, pigs, goats, cattle, horses, buffaloes and sheep the main species. Beyond the economic function, each livestock species also performs social and cultural functions.
Taro [Colocasia esculenta (L.) Schott] is a root crop which is an important staple food in many regions of the world, producing 10.5 million tonnes on 1.4 million hectares a year. The crop is cultivated in wet (rain fed) or irrigated conditions, requiring on average 2,500 mm water per year, and in many countries it is cultivated in flooded plots. It is estimated that taro production could decrease by 40% as a result of the increase in drought and other severe events. In this work, thirty three accessions, including local cultivars, selected and hybrid lines were submitted to long duration drought stress and screened for tolerance. Twelve physiological, morphological and agronomic traits were measured at harvest, and subject to multivariate analysis. Stress indices, Water Use Efficiency and Factorial Analysis were useful for discriminating accessions regarding drought tolerance and yield stability, and drought tolerant and susceptible cultivars were identified. Our results confirm that different taro cultivars have different drought avoidance and tolerance strategies to cope with water scarcity. Better yield performers minimised biomass and canopy loss, while tolerance was observed in cultivars that presented low potential yield, but efficiently transferred resources to enhance corm formation. Among the 33 accessions, two local cultivars showed high yield stability and could be considered as suitable parents for breeding programs, while two others are well adapted to drought, but with overall low yield potential.
The role of intact extraradical mycelium (ERM) as the most effective fungal propagule in the formation of the tripartite symbiosis between indigenous arbuscular mycorrhizal fungi (AMF), rhizobia and subterranean clover was investigated under conditions of Mn toxicity. ERM was previously developed in 8 L pots under greenhouse conditions by growing plants, which exhibited various levels of mycotrophicity and were tolerant to the levels of Mn in the soil used in the experiment (Silene gallica L, Lolium rigidum L, Ornithopus compressus L. and Rumex bucephalophorus L). Contrasting conditions of the integrity of the ERM at the planting of subterranean clover were created by soil disturbance (ERM fragmented -soil disturbed; ERM intact -soil undisturbed). Where an intact ERM was present at the time of planting, growth of subterranean clover was 2.5 times greater after 21 days and 3.9 times after 42 days relative to other forms of AMF propagule. This enhanced growth was associated with a reduction in the Mn concentration of roots due to a greater AMF colonization at 21 days after planting. The protection granted by an enhanced AMF root colonization allowed a greater root nodule development, leading to more N acquisition and plant growth. The ERM can be developed in the soil by mycotrophic plants tolerant to the stressing agent and kept intact at the seeding of the crop to be protected by adopting appropriate tillage techniques.
Sweet potato (Ipomoea batatas L.) is an important crop in the world, cultivated in temperate climates under low inputs. Drought changes the plant biomass allocation, together with the carbon and nitrogen isotopic composition (δ 13 C and δ 15 N), whose changes are faintly known in sweet potato crops. Here, we show the biomass allocation of eight sweet potato accessions submitted to drought during 3 months, using the δ 13 C, δ15N, carbon isotope discrimination (Δ 13 C), total carbon (TC) and water use efficiency (WUE) traits. The tolerant accessions had improved WUE, with higher TPB and TC. Storage roots and shoots had a heavier δ 13 C content under drought stress, with greater 13 C fixation in roots. The Δ 13 C did not show a significant association with WUE. The δ15N values indicated a generalised N reallocation between whole-plant organs under drought, as a physiological integrator of response to environmental stress. This information can aid the selection of traits to be used in sweet potato breeding programs, to adapt this crop to climate change.
Materials and methods
Plant material and experimental setupEight accessions (acc.) of sweet potato (Ipomoea batatas) (designated
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