CHARACTERIZATION OF FORAGE, SWEET AND BIOMASS SORGHUM FOR AGRONOMIC PERFORMANCE AND ENSILABILITY

– This study evaluated sorghum cultivars’ agronomic performance and ensilability with different purpose. The experiment was conducted in Sinop/MT in the 2020 growing season. Eight experimental hybrids from Embrapa (forages 15F30005 and 15F30006, sweet CMSXS 5027, 5030, 5043, and 5045, and biomass 2019B008 and CMSXS 7501), and seven commercial hybrids (forages BRS 658, BRS 659, Volumax, BRS Ponta Negra, the sweet BRS 511, and biomass BRS 716 and AGRI-002E) were planted in a randomized block design, with 15 treatments and three replicates. The highest yields in green matter belonged to the group formed by BRS 716 and CMSXS 5043, with an average of 101.9 Mg ha -1 . The group with the highest dry matter productivity was formed by the cultivars AGRI-002E and BRS 716, with a 28.77 Mg ha -1 average. BRS 716, AGRI-002E, BRS 658, and 659 showed higher dry matter contents (DM), with 297.7 g kg -1 of DM. For buffering capacity, BRS 511 had the lowest value, with 16.2 g kg -1 DM. BRS 511 and CMSXS 5030 presented the highest average, 391.7 g kg -1 DM for water soluble carbohydrates. All genotypes showed potential to be ensiled and produce silages with a good fermentation pattern.

of the country's total area, which represents 72.5 million hectares (ha), is occupied by crops.
However, there are 82 million hectares with agricultural potential outside the Amazon Biome, corresponding to 9.63% of the land area.
Despite the extensive arable area, some regions of the country go through periods of climatic seasonality, with low silage availability and, consequently, decreased food quality.
Consequently, it reduces animal performance since most national bovine herd grows in extensive systems, thus, having pasture as the primary food. Thus, silage production emerges as an alternative to minimize this impact and make the production and use of silage independent (Stella et al., 2016).
The ensiling process consists of creating a fully anaerobic environment, favoring the growth of lactic acid bacteria (LAB). LAB are responsible for fermenting soluble carbohydrates, mainly glucose and fructose, giving rise to organic acids, especially lactate. The acid generated reduces the pH of the medium, which prevents the multiplication of undesirable microorganisms.
Among silage plants, corn (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) are the most used crops for silage production (Souza, 2008). The majority of sorghum genotypes are sensitive to photoperiod (short-day plants) and have greater tolerance than other cereals. They can also adapt to low fertility soils with the presence of aluminum and respond better to fertilization and water availability than maize (Magalhães et al., 2008;Rodrigues et al., 2015).
Five types of Sorghum cultivated in Brazil are classified according to their purposes and agronomic characteristics: grain, biomass, sugar, silage (silage/cutting and grazing), and broom (Rodrigues et al., 2015). Thus, the choice of genotype for silage is based on the purpose it was developed for and its agronomic characteristics, taking into account the behavior of cultivars such as high silage production, a higher proportion of leaves, stay-green, high productivity of grain, digestibility, resistance to pests, diseases, lodging, and its adequacy to mechanized management (Rodrigues et al., 2015).
This work aimed to evaluate the agronomic performance of 15 sorghum genotypes for different purposes and, to attest to their ensilability, to identify experimental genotypes with market potential and suitable to recommend for silage production with good fermentation pattern.  et al., 2013).

Location and experimental conduction
During the experiment period, the accumulated rainfall data were collected in an automatic station of the Embrapa Agrossilvipastoril ( Figure 1).  The buffering capacity analysis was performed by the methodology described by Weissbach et al. (1974). The analysis of water soluble carbohydrates (WSC) was according to the methodology proposed by Silva and Queiroz (2002). With pre-dried forage samples, DM, WSC, and buffering capacity defined, the fermentation coefficient was determined according to Weissbach (1996).
After concluding the other analyses, it was possible to perform the calculations referring to each cultivar's total digestible nutrients (TDN) using the model proposed in the National (2001).

Statistical analysis
The experimental design used was randomized complete block (RCBD), with 15 treatments (genotypes) and three replicates. The data were submitted for analysis of variance, and the means were compared by the Scott-Knott test, adopting the probability level of 5%, using the statistical application genes (Cruz, 2013).
The model used was: Characterization of forage, sweet and biomass sorghum for...

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Being: Y ij = value of the experimental unit that received treatment i in block j; µ = general average effect; T i = genotype fixed effect i, with i = 1, 2, 3, ... and 15; B j = block effect j, with j = 1, 2, and 3; e ij = experimental error associated with observation.

RESULTS AND DISCUSSION
All measured traits showed significant differences for the genotype source of variation, demonstrating the existence of genetic variability between materials (p<0.05).
Nine groups of averages were formed The proportion of leaf, stem, and panicle components varied considerably (Table 2).  the Scott-Knott test, means followed by the same letter represent a statistically homogeneous group at 5% probability.   (Rodrigues et al., 2015). Therefore, when the objective is to use them for animal feed, higher proportions of panicle bring more grains to the ensiled mass, improving the nutritional value of the feed provided.    fell into the group with the lowest average of CHOs, with 178.6 g kg -1 DM ( Table 3).
The sweet genotypes stood out in terms of WSC. However, care must be taken with their use for silage production, as they have low levels of dry matter and are susceptible to undesirable fermentations, such as alcoholic.
However, the high content of WSC can provide enough substrate for a rapid drop in pH to occur, inhibiting other fermentations. It is assumed that a later harvest than that performed in the present work will be beneficial to increasing the DM content and reducing the risk of secondary fermentation. Therefore, further studies should be carried out on using these materials in animal feed and their epiphytic microbiota.
Studies with standard sorghum biomass genotypes for silage production are scarce, given the current demand for their use for animal feed.
However, according to McCullough (1977), the minimum WSC content necessary for a good fermentation is between 60 and 80 g kg -1 DM, a value below that verified for all the materials studied.
Biomass materials can be an alternative for intensive systems despite having a lower nutritional value than sorghum developed for silage production. Thus, these materials can be an alternative for use in intensive systems, given that they are superior in production per unit of area, generating resource savings and crop area optimization. In addition, for some systems, such  (Table 3). Weissbach (1996) showed that forage presents satisfactory fermentation with FC above 45, a value lower than that observed in all cultivars, a fact that can be attributed to the compensation between DM and WSC in the materials, demonstrating that all due to this characteristic, are susceptible to be ensiled and produce silage with a good fermentation pattern.
The chemical characterization was also performed to obtain the materials' in natura characteristics before the ensiling process (Table   4). For crude protein, four groups were formed (P<0.01). The highest average, 69.7 g kg -1 DM, group was composed of the forages BRS For non-protein nitrogen, five groups were formed (P<0.01). The sweete material BRS 511 had the highest average, 345.7 g kg -1 CP, and the forages BRS 658 and 659 had the lowest, 179.6 g kg -1 CP.
Part of the protein in the sorghum grain forms a dense protein matrix composed of glutelins and prolamins rather than NPN (Rooney & Miller, 1981).     (2017), different values were found for BRS 716, ranging between 257.8 g kg -1 DM and 357.2 g kg -1 DM, and for Volumex oscillating between 233.8 g kg -1 DM and 321.9 g kg -1 DM.
When analyzing the lignin and iNDF contents, it is possible to observe that materials with higher amounts of lignin also present higher iNDF. The iNDF is constituted by the fraction of the plant cell wall that is not digested along the gastrointestinal tract (Sniffen et al., 1992). The TDN is a way of expressing food energy used in an animal's diet. According to Keplin (1992), to be considered good quality, silage must present from 640 to 700 g kg -1 DM For all the variables, including the productive characteristics, it was observed that the hybrid CMSXS 5030 stands out in terms of productive potential and ensilability with a good fermentation pattern.