Abstract
There is a lack of agronomic research on the production of custard apple seedlings, especially regarding the ideal substrate and nutritional requirement of the plants. In order to evaluate the accumulation of nutrients in shoots and roots, leaf chlorophyll index and absorption efficiency index (AEI) in custard apple seedlings grown in different substrates and under doses of slow-release fertilizer, an experiment was set in randomized blocks in split-plot scheme with four replicates and eleven plants per plot. The custard apple seedling production method was by sowing. Plots were represented by substrates (fresh sugarcane bagasse; enriched sugarcane bagasse; coconut powder, and commercial organic substrate), whereas subplots were represented by Osmocote Plus® fertilizer doses (0; 3; 6; 9; 12 and 15 kg m-3). The final evaluation was performed at 105 days after sowing. The effect of the slow-release fertilizer on the formation of custard apple seedlings was influenced by the substrate. There was greater accumulation of nutrients as the availability of nutrients increases, as well as increase in nutrient AEI. Custard apple seedlings were found to be more efficient to absorb N > Mg > K > Ca > P > Fe > Mn > Zn. As substrate, coconut powder associated with the 9 kg m-3 slow-release fertilizer dose is recommended to produce custard apple seedlings.
Highlights
In Northeast Brazil, the cultivation of custard apple is in full expansion, and irrigated fruit production stands out as the main agribusiness activity in the São Francisco Valley, despite the great agro-industrial potential, this region faces problems with the scarcity of good-quality seedlings for the planting of new orchards (Melo Júnior et al, 2015), including of custard apple.Using regional materials from the local agro-industry as potential substrates for seedling production may lead to reduction in the environmental impact, minimizing production costs and presenting itself as a feasible alternative for farmers
In order to evaluate the accumulation of nutrients in shoots and roots, leaf chlorophyll index and absorption efficiency index (AEI) in custard apple seedlings grown in different substrates and under doses of slow-release fertilizer, an experiment was set in randomized blocks in split-plot scheme with four replicates and eleven plants per plot
Plots were represented by substrates, whereas subplots were represented by Osmocote Plus® fertilizer doses (0; 3; 6; 9; 12 and 15 kg m-3)
Summary
In Northeast Brazil, the cultivation of custard apple is in full expansion, and irrigated fruit production stands out as the main agribusiness activity in the São Francisco Valley, despite the great agro-industrial potential, this region faces problems with the scarcity of good-quality seedlings for the planting of new orchards (Melo Júnior et al, 2015), including of custard apple.Using regional materials from the local agro-industry as potential substrates for seedling production may lead to reduction in the environmental impact, minimizing production costs and presenting itself as a feasible alternative for farmers. It is important to remember that the substrate must have good cation exchange capacity, physical stability and biological sterility, besides adequate pH, electrical conductivity, nutrient contents, C/N ratio, water/air ratio, total porosity, water retention capacity and drainage (Barreto et al, 2018). Among agroindustry wastes, those from sugarcane industry stand out, such as fresh sugarcane bagasse, used by local farmers of mango and grape for soil mulching, and enriched sugarcane bagasse, which is an organic compound formed by mixing sugarcane bagasse, filter cake, sugarcane washing sludge and vinasse, and used as organic fertilizer by local farmers. Fertilization of fruit crops using fertilizer sources with slow or controlled nutrient release is efficient and enables continuous nutrient availability, lower occurrence of deficiency and lower nutrient losses through leaching, making split applications of other sources unnecessary and reducing costs (Almeida et al, 2019)
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