engleski

Green beans (Phaseolus vulgaris L.) root nodules number after treatment with nettle leaf extract

Nitrogen fixation by soil bacteria could be used as a source of plant available nitrogen without fuel consumption. Symbioses between N fixing bacteria and legumes occur under favourable soil conditions regarding pH, salinity, amount of water and presence of nutrients, while excess soil N inhibits nodulation. Nettle leaf extract, commonly used as source of nitrogen in organic farming, is applied in green beans production to test its effects on root nodulation. The experimental plants were sown on August 9 th 2016. Nettle dry leaves (183 g/10 L of water) macerated 24 hours (short) and applied foliarly, and the same amount of nettle dry leaves macerated 14 days (long) and applied by watering, were compared to plots fertilized with urea or without N fertilization. Six plants per treatment were sampled during last harvesting date, on September 11 th 2016, for measurements of shoot dry weight, root dry weight and number of nodules per each plant. Nodules number per plant was the highest after application of nettle extract of long maceration (20.3 ±9.9) compared to nettle extract of short maceration (11.3±10.8), urea (5.0 ±6.0) and untreated plants (4.5±3.9). Root dry weight (g/plant) was the highest after application of nettle extract of short and long maceration (0.95±0.26 and 0.90±0.18, respectively) than after urea application and untreated plants (0.57±0.20 and 0.63±0.21, respectively). Urea treated plants had greater shoot/root ratio than nettle treated plants of short and long maceration (12.19±6.74 and 9.48±2.29, respectively), while untreated plants were similar to all treatments. Nodules number per root weight (g / plant) was the highest after application of nettle extract of short and long maceration (22.7±10.3 and 12.9±13.3, respectively) than after urea application and untreated plants (8.7±9.2 and 7.2±6.3, respectively) but the difference was of low significance ( p =0.064). Shoot dry weight was similar for all treatments. Nodules number was negatively correlated to shoot/ root ratio (-0.57, p<0.05). The results indicate the positive effect of nettle extract on beans nodulation and root growth. The effect of urea to nodulation was similar to untreated plants except it enhanced shoot growth. The research must be continued to confirm the positive effect of nettle extract on green beans nodulation.

fertilization, legumes, organic farming, symbiotic N fixation, Urtica dioica L.

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