Physiological quality of sweet sorghum [Sorghum bicolor (L.) Moench.] seeds in response to planting density in semi-arid region

Abstract

Sweet sorghum is a bioenergy crop that produces high amount of ethanol per hectare even under semi-arid conditions, serving as an alternative to sugarcane inter-season in Brazil. The aim of this study was to evaluate the influence of planting density on the physiological quality of sweet sorghum seeds. Two sweet sorghum cultivars (BRS 506 and SF-15) were submitted to a spacing of 50, 60, 70 and 80 cm between rows, and 8, 12 and 16 cm between plants. The experimental design was of randomised blocks with four replications in a 2 x 4 x 3 factorial scheme, comprising two cultivars, four row spacings and three spacings between plants. The following were evaluated from the collected panicles: seed quantity, 100 seed weight, water content, germination, first germination count and speed of germination, accelerated ageing, and seedling vigour. It was found that both the cultivar and the arrangement of plants in the field affect the physiological quality of sweet sorghum seeds. The BRS 506 cultivar is recommended for seed production under semi-arid conditions, at a spacing of 16 cm between plants and 80 cm between rows, and a density of 78,125 plants per hectare.

Interference of Spacing on the Growth and Biomass of Sweet Sorghum

“…Results can be found in the literature which explain that increases in biomass are related to several factors besides spacing, such as the species, cultivar and environment (SILVA et al, 2017). It is not necessary to look much further than sweet sorghum to confirm this.…”

“…The decision on inter-row and plant spacing should be taken with great care, since the use of higher plant densities in the row may be a limiting factor that could hinder the expression of the production potential of new cultivars (May et al, 2012c;SILVA et al, 2017).…”

“…It has a C4 metabolism, a short cycle (120 to 130 days), high photosynthetic efficiency, is well adapted to different environments, does not require large amounts of nutrients, and is tolerant to drought, salinity and toxic aluminium (DURÃES, 2011;OLIVEIRA et al, 2012). It is therefore, a good option for cultivating in semi-arid regions, such as the Northeast of Brazil, since this region has soils that are little-developed and of low permeability, a source of water that is generally dependent on the rainy season, and scarce rainfall concentrated over a short period of time (ARAÚJO, 2011;NUNES et al, 2014;SILVA et al, 2017).…”

“…Variations in planting arrangement have a great impact on crop development, by influencing the competition for essential environmental resources such as water, light and nutrients (COSTA et al, 2017;OLIVEIRA et al, 2017;SILVA et al, 2017). Theoretically, the best arrangement is considered the one with more-uniform plant distribution by area, and that allows the best use of these resources, directly influencing the diameter and height of the plant stem (ARGENTA, 2001;MAY et al, 2012a).…”

Agronomic Evaluation of Sweet Sorghum in Semiarid Region: Cultivar and Spacing Effects

“…Soil preparation was performed with plowing followed by harrowing. According to the soil analysis (Appendix A: Tables A1 and A2) of the experiment area and recommendations of Silva et al (2017b), the crop was fertilized with 30, 50, and 45 kg ha -1 of N, P 2 O 5 , and K 2 O, respectively, at the time of sowing for both years, taking as sources for each nutrient the mineral fertilizers urea, simple superphosphate, and potassium chloride. Twenty days after sowing, a topdressing was applied of fertilizer with 140 and 45 kg ha -1 of N and K 2 O, respectively.…”