Abstract
The objective of this work was to verify the influence of light environments combined with rhizobia inoculation on cowpea growth and productivity. A completely random design was used in a 4x4 factorial scheme, with four light environments, four nitrogen sources and eight replicates in split plot parcels. Light environments were set by means of photo-conversion and thermo-conversion nettings (Aluminet®, red net and black net) and control treatment without shading (full sun). Nitrogen sources were constituted by the strains INPA 03-11B - SEMIA 6462 (Bradyrhizobium elkanni) and UFLA 03-84 - SEMIA 6461 (Bradyrhizobium viridifuturi), and two control treatments: with 70 kg ha-1 of mineral nitrogen and without N. Plant height, indices of chlorophyll a, b and total chlorophill, the number of leaves, number of nodules, dry matter of nodules, dry matter of the aerial portion, dry matter of roots and total dry matter, relative efficiency, gathering of nitrogen in the aerial portion, number, length and matter of pods per plant and dry matter of 100 grains, were evaluated. . There was interaction between light conditions and nitrogen sources for the number of nodules. Individual effect was observed in all other variables. Strain INPA 03-11B was able to promote higher nodulation in cowpea plants in light environments under full sun and Aluminet and the strain UFLA 03-84 only under full sun conditions. However, the efficiency of diazotrophic bacteria to promote vegetative growth, nitrogen gathering and production was not influenced by different light environments. Thus, full sun cultivation is recommended, independently of the nitrogen source used.
Highlights
Plant cultivation technologies may be improved for production in small and urban areas, primarily when aiming production of organic crops and increasing the accessibility to better quality foods for the population.One of the technologies available nowadays when considering the production of plants in small areas consists in the use of nets
In cowpea higher indices of chlorophyll were obtained when plants were submitted to shading environments, the highest mean value for dry matter of the aerial portion was obtained in plants under full sun environments (Santos et al 2011)
There was no interaction of light environments with nitrogen sources for the indices of chlorophyll a, b and total chlorophyll (CLA, CLB and CLT), number of leaves (NL), plant height (H), matter of dry nodules (DMN), matter of the dry aerial portion, dry roots and total dry matter (MDAP, DMR and DMT), gathering of nitrogen in the aerial portion (GNAP), relative efficiency (RE), number, length and matter of pod per plant (NPP, LPP and MPP) and matter of 100 grains (M100G)
Summary
One of the technologies available nowadays when considering the production of plants in small areas consists in the use of nets. These nets modify the quality and quantity of incident light and interfere, directly or indirectly, in the photosynthetic apparatus of plants (Lacerda et al 2010; Santos et al 2011; Taiz and Zeiger 2013). Indices of chlorophyll, the number of leaves, foliar area, and the dry matter of the aerial portion of several species such as bean, corn, coffee and tomato, among others, may increase (Lacerda et al 2010; Henrique et al 2011; Santos et al 2011; Ilic et al 2012; Hirata and Hirata 2015). In cowpea higher indices of chlorophyll were obtained when plants were submitted to shading environments, the highest mean value for dry matter of the aerial portion was obtained in plants under full sun environments (Santos et al 2011)
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