Summary
The effect of reduced solar radiation on associative N2-fixation and plant parameters was studied in three field experiments (1978–80). ‘Gahi-3’ pearl millet (Pennisetum americanum (L.) K. Monch.) field plots were shaded with saran shade cloth that reduced solar radiation by 50% and 75%. Acetylene reduction activity (ARA) was reduced by shading in one of the three experiments. The two non-responding experiments were conducted on a wall-drained, low-activity site (ARA means ranging 17–68 n moles ethylene core−1 h−1), the responding experiment was conducted on a poorly drained, high-ARA site.
Shading affected the plants drastically, reducing fresh weight and dry matter yields up to 46% (50% shade) and 57% (75% shade). Shading also reduced dry matter percentage from 19.6 (no shade) to 15.3 (75% shade) and increased nitrogen content from 0.6% (no shade) to 1.53% (75% shading). However, shading did not affect protein yield. Inoculation withAzospirillum brasilense had no measurable effect on yield or acetylene reduction in the first two experiments.
In the third experiment, shading reduced mean ARA of inoculated plots over 100% but had no significant effect on control plots. Inoculation significantly increased ARA in the nonshaded plots but not in shaded plots. Acetylene reduction activity was high, with means ranging between 208 and 465 n moles ethylene evolved core−1 h−1. Soil moisture and millet growth stage also affected acetylene reduction activity.
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Smith, R.L., Schank, S.C. & Littell, R.C. The influence of shading on associative N2 fixation. Plant Soil 80, 43–52 (1984). https://doi.org/10.1007/BF02232938
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DOI: https://doi.org/10.1007/BF02232938