Potato (Solanum tuberosum L.) is an important food and cash crop in Ethiopia; serving, as a food security crop due to its nutrition content, wider adaptability and early maturing behavior. However, the yield of the crop is constrained by a number of factors. Among which unspecified seed tuber size and limited availability and distribution of improved varieties are among the important limiting factors. A field experiment was conducted to study the effects of seed tuber size on growth and yield performance of potato varieties at Agarfa, Agricultural Technical and Vocational Education and Training College experimental field during 2017. The treatments consisted of three potato varieties (Gudenie, Jalene and Kellacho) and three seed tuber sizes (25-34, 35-45 and 46-55 mm). The experiment was laid out in a randomized complete block design with a factorial arrangement and replicated three times. The results showed that, seed tuber size and varieties significantly affected phenological parameters, stem number, leaf area index, stem density, marketable, unmarketable and total tuber yield, shoot fresh and dry weight, underground fresh weight, and medium weight of tuber size. Leaf number, and underground dry weight and tuber size were significantly affected only by seed tuber size. Varieties and seed tuber size interact to influence plant height, leaf area, number of tuber per plant, dry matter concentration and harvest index. Gudenie and Jalene produced the highest total tuber and marketable yields. Large seed tuber size (46-55 mm) produced higher marketable tuber yields than medium and small tuber sizes. In conclusion, Gudenie variety and large seed tuber size showed superior performance both for tuber yield and tuber dry matter concentration compared with the remaining varieties and small tuber size. Therefore, farmers are encouraged to produce Gudenie or Jalene variety with the use of medium to large seed tuber size for potato production.

Potato is a high potential food security crop in Ethiopia due to its high yield potential and nutritional quality tuber, short growing period, and wider adaptability. Arsi administrative province is one of the potential potato growing areas in southern parts of Ethiopia. The potato is grown there as a field crop, and it substantially supplies potatoes to the whole country. Despite the suitability of this area for high quantity and quality potato production in the country, there are several constraints, which drastically affect to the low production and productivity of potato crop by smallholder farmers. The objective of this study was to evaluate the potato seed system, storage, pre-planting treatment practices applied and marketing systems followed by potato producing farmers and to suggest improvement options. In this research, a combination of literature study, expert elicitation, group discussion, field observation, and questionnaire base survey were used. The result of this study showed that a number of factors constraining the system including: unavailability of high quality seed tubers, unavailability of improved varieties, unavailability of improved storage structure, low price of the produce and poor transportation. It is concluded that availability of improved potato varieties, improved storage facilities, use of pesticides and better marketing opportunities are crucial to improve the potato crop system, to alleviate poverty and improve food security of smallholder farmers in the Arsi area in particular and in the country in general.

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Supplying nitrogen to crops through selecting high N fixing legumes and effective inoculant is one of the key strategies to improve crop productivity. However, studies related to the effect of Bradyrhizobial inoculation on leaf growth, its functioning in relation to photosynthesis, and transpiration efficiency (WUE) of cowpea [ Vigna unguiculata (L.) Walp] varieties in the tropics were inadequate. A two-year field experiment was conducted at three sites to evaluate the effect of inoculation on leaf growth, gas exchanges and photosynthetic efficiency of cowpea varieties. The study treatments were composed of four varieties, Keti (IT99K-1122), TVU, Black eye bean, and White wonderer trailing and three levels of inoculation (non-inoculated or inoculated with Bradyrhizobium strains CP-24 or CP-37). Gas exchange was measured on live plants at 67–77 days after sowing, between 8:00 to 11:00 a.m. and 14:00 to 16:00 p.m. Leaf growth parameters (leaf number and leaf area) were measured by destructive sampling, and the yield data was determined by harvesting plants in the three central rows at physiological maturity. Variety TVU performed best in terms of leaf number, photosynthesis rate, and WUE. Whereas, Black eye bean revealed superior performances for leaf area, leaf area index, and stomatal conductance compared with the rest two varieties. The effect of inoculation was significant with 14.0, 23.8, 13.7, and 11.0% advantage in leaf area, leaf area index, net photosynthesis, and WUE, respectively. Moreover, the performance of cowpea of the 2018 cropping season showed a relative advantage over 2019 in terms of leaf number, leaf area, leaf area index, net photosynthesis, and stomatal conductance. Therefore, inoculating cowpea varieties with effective Bradyrhizobium strain can be a viable alternative to enhance growth, gas exchange, photosynthetic efficiency, and grain yield.

Yield response of field-grown cowpea (Vigna unguiculata (L.) Walp.) varieties to Bradyrhizobium inoculation

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Chemical phosphatic fertilizers are mainly produced from phosphate rocks, a natural reserve that is depleting rapidly. These chemical phosphatic fertilizers are polluting the environment at an alarming rate as a result of injudicious application to farmlands. On the other hand, phosphate-solubilizing biofertilizers (PSBs) are often considered better alternatives to industrial phosphatic fertilizers in many ways. PSBs are microorganisms capable of solubilizing insoluble forms of phosphate into soluble plant-usable forms. This paper is written with the objective of discussing the impacts of phosphatic fertilizers and making the case for why we should shift to PSBs instead. Phosphatic fertilizers have numerous impacts on the environment (water bodies, land resources, and air), and micro- and macro-organisms, including humans. Chemical fertilizers also tend to be more expensive, especially for farmers in developing countries. On the contrary, PSBs tend to be safer and way more beneficial than their chemical counterparts in that they are environmentally friendly and cheaper options of availing plant-usable phosphorus. PSBs are also involved in other beneficial roles such as the production of phytohormones and secretion of anti-phytopathogenic metabolites. The phytohormones enhance plant growth and the metabolites render crops immunity against phytopathogens. Hence, it is vital to replace chemical phosphatic fertilizers with PSB inoculants both to prevent the irreversible impacts of chemical fertilizers and to take advantage of the numerous benefits of PSBs. Moreover, it does not seem as if there is an option given the fact that the global phosphate reserve is depleting and the impact of fertilizer on the environment is worsening as time goes by.