Influence of organic and mineral fertilization on germination, leaf nitrogen, nitrate accumulation and yieldof vegetable amaranth
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Date
2012Author
Onyango, Cecilia M.
Harbinson, Jeremy
Imungi, Jasper K.
Shibairo, Solomon I
Kooten, Olaf van
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
The influence of manure and diammonium phosphate (DAP) mineral fertilizer on germination,
leaf nitrogen content, nitrate accumulation and yield of vegetable amaranth (Amaranthus
hypochondriacus) was investigated.Field trials were set up at the University of Nairobi Field Station
at the Upper Kabete Campus during the long rains of March–May in 2007 and 2008. Trials
were laid out as complete randomized block design with four fertilization treatments:20,40,and60
kg nitrogen (N) ha−1suppliedbyDAP(18:46:0),40kgNha−1suppliedbycattlemanureandan
unfertilized control variant. The vegetables were harvested at three maturity stages at 6, 7, and 8
weeks after planting. Results indicated that there were significant differences between treatments in
germination percentage,leaf nitrogen content,nitrate accumulation and vegetable yield.Plants that
received manure had a higher germination percentage than those that received the same amount of
N supplied by the chemical fertilizer DAP.The yields generally increased from week 6 to week 8.The
highest yield was recorded in plots receiving 40 kg N ha−1 from DAP at eight weeks after planting.
Plots that were supplied with manure recorded the lowest yield when compared to the fertilizer treated
plots at all rates. Leaf nitrogen content increased with increasing rate of N but only when N was
supplied by DAP fertilizer.The leaf nitrogen content decreased with increasing age of the plants.The
leaf nitrate content increased with increase in DAP application rate. Results indicate that manure
application produced quality vegetables interm so flow nitrate levels, but leaf nitrogen and vegetable
yields were low. DAP application effected higher yields,but the vegetables had high though acceptable
nitrate levels.
Citation
Journalof Plant Nutrition, 35:342–365, 2012Publisher
Taylor & Francis 1Department of Plant Scienceand Crop Protection,Faculty ofAgriculture, University ofNairobi, Kangemi, Kenya 2Department of Plant Sciences,Wageningen University, Wageningen, the Netherlands 3Department of Food Science, Nutritionand Technology,Faculty ofAgriculture, University ofNairobi, Kangemi, Kenya