Acúmulo de nutrientes, produção e qualidade do caldo de três variedades de cana-de-açúcar nos ciclos de cana-planta, primeira, segunda e terceira rebrotas

Abstract

vvSugarcane breeding programs have made available more productive varieties and with different adaptations to production environments. Some of these varieties have more restricted adaptation, being demanding in soil fertility, water availability and less clayey soils. On the other hand, other of these new varieties have a more comprehensive adaptation, showing good yields of stalks and sugars even when grown in more restrictive environments when it comes to soil fertility, water availability and medium to clayey soils. The RB92579 variety was, in the last harvests, one of the most planted in Alagoas, by both small and medium producers. Information related to RB92579 is available, however, for the varieties RB961552 and RB98710 there are few reports in the literature regarding the productive potential and quality of the juice, especially in successive cuts, since both RB961552 and RB98710 are more recently launched varieties. Thus, the objective of the present research was to evaluate in the cane-plant cycles, first, second and third regrowth the nutritional status, the production of industrialized stalks, quality of the juice and the accumulation of nitrogen, phosphorus and potassium by RB961552 and RB98710, comparatively to RB92579, standard variety. The study was conducted in the edaphoclimatic environment of Anadia, in the wild of Alagoas, in a dystrophic yellow latosol, belonging to the Triunfo Plant. Prior to its implantation, soil samples were collected and, in possession of the analytical results, limestone and plaster were applied to increase the base saturation to 60% in the 0 to 20 cm layer and decrease the aluminum saturation in the 20 layer. to 40 cm. After the application of limestone and plaster, the experimental area was plowed and grated, then grooved in the space of one meter. The three varieties of sugarcane were planted using a randomized block design with five replications. The chemical fertilizer applied to the bottom of the planting furrow was the one usually used by the plant: 500 kg per hectare from 09-14-22. The plots consisted of seven eight-meter-long ridges. The planting density was 18 buds per meter of furrow, using eight-month-old cane seedlings. After planting, pre-emergent herbicide was applied for weed control. In the phase of maximum sugarcane growth, leaf samples were collected to assess the nutritional status. In December of the year following planting, sugarcane was cut, evaluating the production of industrialized stalks and the quality of the juice. After the harvest of the cane-plant, the first regrowth was fertilized, applying a dose equivalent to 500 kg of the fertilizer 20-05-20 per hectare, with manual distribution of the fertilizer. In December of the subsequent year of the cut of the cane-plant, the first regrowth was cut, again evaluating the production of industrialized stalks and the quality of the juice. After the first regrowth was cut, the second regrowth was fertilized with 500 kg of fertilizer 20-05-20 per hectare. After cutting the second sprout, the third sprout was fertilized with 500 kg of fertilizer 20-05-20 per hectare. Both in the cane of the first regrowth and in the second and third regrowth, the same procedures used in the cane plant were adopted, for the evaluation of industrialized culms and the quality of the juice. The data obtained were subjected to analysis of variance and the means compared by the Scott-Knot test at 5% probability. In all cycles there was a difference between the varieties regarding the levels of nutrients in the leaf blade, but none of the three varieties stood out in general for all nutrients. Only for calcium, magnesium, boron, iron and zinc were found leaf levels suitable for all varieties, in all four cycles. There was a general nutritional deficiency for copper levels and in no cycle or variety, the levels reached 6.0 mg per kg of dry leaf limb material, minimum content of sufficiency. For manganese, the plants showed sufficient levels only in the second regrowth. For the cycles, the manganese leaf contents are well below the minimum sufficiency limit: 25 mg per kg of dry matter of leaf blade. There was an effect of variety and cycles on the production of industrializable culms, with a decrease in productivity throughout the study. The total amount of industrialized stalks produced by RB92579, in the four cycles, was 374 t per hectare. Compared to RB92579, the stalk production of RB961552 and RB98710 was 93.6 and 86.6%, respectively. There was a variety effect for the production of recoverable sugars, soluble solids, apparent sucrose in stalks and fiber, however the broth purity percentage was not influenced by variety. There was a cycle effect for TCH, ATR per t of stalks, ATR per hectare, apparent sucrose in stalks, broth purity and percentage of fiber in stalks. The total recoverable sugars produced by RB92579, in the four cycles, was 52.58 t per hectare, but the production of recoverable sugars by RB961552 and RB98710 was 87% of RB92579. In the four cycles, the removal of nutrients by the cane was very large, reaching average values of approximately 400 kg of nitrogen, 65 kg of phosphorus and 800 kg of potassium per hectare. Keyword: nutritional efficiency, production system, mineral nutrition, Saccharum spp.Sugarcane breeding programs have made available more productive varieties and with different adaptations to production environments. Some of these varieties have more restricted adaptation, being demanding in soil fertility, water availability and less clayey soils. On the other hand, other of these new varieties have a more comprehensive adaptation, showing good yields of stalks and sugars even when grown in more restrictive environments when it comes to soil fertility, water availability and medium to clayey soils. The RB92579 variety was, in the last harvests, one of the most planted in Alagoas, by both small and medium producers. Information related to RB92579 is available, however, for the varieties RB961552 and RB98710 there are few reports in the literature regarding the productive potential and quality of the juice, especially in successive cuts, since both RB961552 and RB98710 are more recently launched varieties. Thus, the objective of the present research was to evaluate in the cane-plant cycles, first, second and third regrowth the nutritional status, the production of industrialized stalks, quality of the juice and the accumulation of nitrogen, phosphorus and potassium by RB961552 and RB98710, comparatively to RB92579, standard variety. The study was conducted in the edaphoclimatic environment of Anadia, in the wild of Alagoas, in a dystrophic yellow latosol, belonging to the Triunfo Plant. Prior to its implantation, soil samples were collected and, in possession of the analytical results, limestone and plaster were applied to increase the base saturation to 60% in the 0 to 20 cm layer and decrease the aluminum saturation in the 20 layer. to 40 cm. After the application of limestone and plaster, the experimental area was plowed and grated, then grooved in the space of one meter. The three varieties of sugarcane were planted using a randomized block design with five replications. The chemical fertilizer applied to the bottom of the planting furrow was the one usually used by the plant: 500 kg per hectare from 09-14-22. The plots consisted of seven eight-meter-long ridges. The planting density was 18 buds per meter of furrow, using eight-month-old cane seedlings. After planting, pre-emergent herbicide was applied for weed control. In the phase of maximum sugarcane growth, leaf samples were collected to assess the nutritional status. In December of the year following planting, sugarcane was cut, evaluating the production of industrialized stalks and the quality of the juice. After the harvest of the cane-plant, the first regrowth was fertilized, applying a dose equivalent to 500 kg of the fertilizer 20-05-20 per hectare, with manual distribution of the fertilizer. In December of the subsequent year of the cut of the cane-plant, the first regrowth was cut, again evaluating the production of industrialized stalks and the quality of the juice. After the first regrowth was cut, the second regrowth was fertilized with 500 kg of fertilizer 20-05-20 per hectare. After cutting the second sprout, the third sprout was fertilized with 500 kg of fertilizer 20-05-20 per hectare. Both in the cane of the first regrowth and in the second and third regrowth, the same procedures used in the cane plant were adopted, for the evaluation of industrialized culms and the quality of the juice. The data obtained were subjected to analysis of variance and the means compared by the Scott-Knot test at 5% probability. In all cycles there was a difference between the varieties regarding the levels of nutrients in the leaf blade, but none of the three varieties stood out in general for all nutrients. Only for calcium, magnesium, boron, iron and zinc were found leaf levels suitable for all varieties, in all four cycles. There was a general nutritional deficiency for copper levels and in no cycle or variety, the levels reached 6.0 mg per kg of dry leaf limb material, minimum content of sufficiency. For manganese, the plants showed sufficient levels only in the second regrowth. For the cycles, the manganese leaf contents are well below the minimum sufficiency limit: 25 mg per kg of dry matter of leaf blade. There was an effect of variety and cycles on the production of industrializable culms, with a decrease in productivity throughout the study. The total amount of industrialized stalks produced by RB92579, in the four cycles, was 374 t per hectare. Compared to RB92579, the stalk production of RB961552 and RB98710 was 93.6 and 86.6%, respectively. There was a variety effect for the production of recoverable sugars, soluble solids, apparent sucrose in stalks and fiber, however the broth purity percentage was not influenced by variety. There was a cycle effect for TCH, ATR per t of stalks, ATR per hectare, apparent sucrose in stalks, broth purity and percentage of fiber in stalks. The total recoverable sugars produced by RB92579, in the four cycles, was 52.58 t per hectare, but the production of recoverable sugars by RB961552 and RB98710 was 87% of RB92579. In the four cycles, the removal of nutrients by the cane was very large, reaching average values of approximately 400 kg of nitrogen, 65 kg of phosphorus and 800 kg of potassium per hectare.