Agricultural production on the Mahafaly Plateau in SW-Madagascar has traditionally been based on subsistence rain-fed agriculture, with yields declining as a result of low soil fertility, recurrent droughts, and erratic rainfall. Market-oriented vegetable production in this area may help households improve their nutrition and diversify their income. In field trials between the 2013 and 2016 dry cropping seasons, the feasibility of carrot (Daucus carota L.) and onion (Allium cepa L.) production was assessed by testing effects of manure and charcoal amendments, shading, and seed quality on yields. Due to damage caused by cyclones and strong winds, only data from 2013 and 2016 are reported in this paper. Additionally to the field experiments, effects of salinity on seed germination were also examined under laboratory conditions and in the field. Carrot dry matter (DM) yields were 0.24 to 2.76 t·ha−1 while those of onion were 0.15 to 0.99 t·ha−1 DM. While the combination of manure and charcoal application had only minor effects on crop growth, manure alone increased carrot yield by 26% across years. After one cropping season, manure application reduced soil pH from 9.0 to 8.6 and increased soil Corg from 0.87 to 1.76%, N from 0.08 to 0.14%, and P from 10.6 to 15.1 mg·kg−1. Shading reduced carrot yields from 0.87 to 0.58 t·ha−1 DM in 2013 and from 1.87 to 0.85 t·ha−1 DM in 2016, but increased onion yield in 2013 from 0.24 to 0.62 t·ha−1 DM. Carrot seed procured locally performed better in the field than seed imported from the capital which translated into differences in seedling emergence. Saline irrigation water (electrical conductivity = 7.03 mS·cm−1) reduced seedling emergence rate of carrot from 73 to 20% and for onion from 44 to 28% and unprimed seeds performed better than primed ones. Using shading during the dry season is not advisable for carrot and onion production, but improving seed quality and targeted use of soil amendments (time of manure application, manure quality) may enhance vegetable yields.

中文翻译：

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改善马达加斯加西南部半干旱、盐碱条件下的蔬菜生产

马达加斯加西南马哈法利高原的农业生产传统上以自给自足的雨养农业为基础，由于土壤肥力低、反复干旱和降雨不稳定，产量下降。该地区以市场为导向的蔬菜生产可以帮助家庭改善营养并实现收入多样化。在 2013 年至 2016 年旱作季节的田间试验中，胡萝卜（胡萝卜L.) 和洋葱 (洋葱L.) 通过测试粪肥和木炭改良剂、遮荫和种子质量对产量的影响来评估产量。由于飓风和强风造成的破坏，本文仅报告了 2013 年和 2016 年的数据。除田间试验外，还在实验室条件下和田间检验了盐度对种子萌发的影响。胡萝卜干物质 (DM) 产量为 0.24 至 2.76 t·ha-1洋葱为 0.15 至 0.99 t·ha-1DM。虽然粪肥和木炭的组合对作物生长的影响很小，但仅粪肥就可以使胡萝卜的产量在多年内增加 26%。一个种植季节后，施肥可将土壤 pH 值从 9.0 降低到 8.6，并增加土壤 C组织0.87 至 1.76%，N 0.08 至 0.14%，P 10.6 至 15.1 mg·kg-1. 遮荫将胡萝卜产量从 0.87 减少到 0.58 t·ha-12013 年干物质从 1.87 到 0.85 t·ha-12016 年干物质，但 2013 年洋葱产量从 0.24 增加到 0.62 t·ha-1DM。当地采购的胡萝卜种子在田间的表现优于从首都进口的种子，这转化为出苗率的差异。盐水灌溉水（电导率=7.03 mS·cm-1) 将胡萝卜的出苗率从 73% 降低到 20%，将洋葱的出苗率从 44% 降低到 28%，并且未处理过的种子比处理过的种子表现更好。对于胡萝卜和洋葱的生产，不建议在旱季使用遮荫，但提高种子质量和有针对性地使用土壤改良剂（施肥时间、肥料质量）可能会提高蔬菜产量。