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This study aimed to estimate the heterosis, heterobeltiosis, and inbreeding depression in grain sorghum hybrids. Twenty-five hybrids were evaluated in two seasons. The evaluated traits were days to flowering (FL), plant height (PH), grain yield (GY), and thousand grains mass (M1000). The contrast tested were F1 hybrids vs. check cultivars, F1 hybrids vs. parental lines, and F1 hybrids vs. F2 hybrids. The hybrids 1167048, 1099044, 1170017, and 1169054 had a five-day less flowering time than their parental lines. The hybrid 1170017 had a high grain yield (6.23 t ha-1) with 43.55% of heterobeltiosis. The diversity between lines was narrow. However, hybrids with higher grain yield, heterosis, and heterobeltiosis showed higher genetic distances from their parental lines. The inbreeding depression between F1 vs. F2 was 30%, indicating that using F1 hybrids seeds is worthwhile.

Forage sorghum presents tall plants, what makes mechanical seed harvesting a difficult task. Plant hormones can reduce plant height and facilitate the harvesting. Thus, the objective of this study was to evaluate the effect of the growth regulator trinexapac-ethyl on plant height and seed yield in forage sorghum. This research was carried out at Embrapa Maize and Sorghum, in two seasons (2017 and 2018), in a randomized complete block design, four replications and three varieties (BRS Ponta Negra, 1141574 and 0947216) under application of Trinexapac-ethyl in two stages of the plant growth (V8, V12, V8 + V12). The characteristics evaluated were: plant height, seed yield and mass of 1000 seeds. The effect of the hormone was significant in both stages of growth, with a significant reduction in plant height. The hormone applied twice at growth stages V8 + V12 had a greater effect in reducing plant height. However, the hormone reduced seed yield in the three varieties, what implies the need for further studies comparing the advantage of plant height reduction and the loss in seed yield. Made available in DSpace on 2021-10-27T13:00:27Z (GMT). No. of bitstreams: 1 Trinexapac-ethyl-reduces.pdf: 493049 bytes, checksum: 42bff85016ca6a8a2608bce5b50fbd45 (MD5) Previous issue date: 2021

The objective of this study was to estimate the adaptability and stability of grain sorghum hybrids grown under post-flowering water stress and non-stress conditions. The trials were carried out in Nova Porteirinha-MG during the season of 2014 and 2015, and in Teresina-PI in the 2014 season. Twenty-nine-grain sorghum hybrids were evaluated, in a randomized complete block design, with three replications. Plots consisted of four lines with 3 m long. The grain yield data were submitted to the individual variance analysis, having considered the effects of the hybrids as fixed and the other effects as random. The joint analysis was carried out, and when the interaction genotypes x environments was significant, the grain yield data were submitted to the adaptability and stability analysis by the GGE biplot method. A substantial reduction in the grain yield in environments with water stress was found. The highest yielding hybrids under water stress conditions in Nova Porteirinha-MG were 50A50, AG1080, AG1090, DKB550, DKB590, Jade, and BM737, and the highest yielding hybrids under the water stress in Teresina-PI were 1G282, 1G244, and A9721R. Considering all environments, the highest yielding hybrids were 1G282, DKB540, A9721R, 1G100, and AG1090. Made available in DSpace on 2017-09-23T00:13:45Z (GMT). No. of bitstreams: 1 Performancegrain.pdf: 1041239 bytes, checksum: 8ccfa98437ab622e9f993a05fe203971 (MD5) Previous issue date: 2017-09-21

O objetivo do presente trabalho foi selecionar linhagens de sorgo mais tolerantes a seca e responsivas a melhoria do ambiente. Os tratamentos foram arranjados em um esquema fatorial, composto por 25 linhagens e dois regimes hidricos. Os experimentos foram realizados em tres anos consecutivos (2006, 2007 e 2008), totalizando seis experimentos. O delineamento utilizado foi o de blocos casualizados, com tres repeticoes. Para selecao dos genotipos foram estimados parâmetros de adaptabilidade e estabilidade para produtividade de graos utilizando os metodos univariados de Lin & Bins e Annicchiarico, e analise multivariada AMMI. A selecao para adaptabilidade geral pelos dois primeiros metodos e bastante similar, diferindo, no entanto do terceiro metodo. A produtividade media das linhagens no ambiente com estresse foi 39% menor quando comparado ao ambiente sem estresse hidrico. Foram detectadas diferencas significativas para as interacoes linhagens (L) x anos (A), linhagens (L) x regime hidrico (R) e LxAxR, indicando a complexidade de se trabalhar com selecao para tolerância a seca em sorgo em nivel de campo. Os metodos univariados complementaram o metodo AMMI, possibilitando a selecao de linhagens tolerantes, estaveis e responsivas ao ambiente. As linhagens mais tolerantes e estaveis foram 9929020, CMSXS 230B e N 95B, seguidas pelas linhagens BR 008B, Tx 2737 e Tx 2908, de produtividades elevadas, mas de estabilidades intermediarias.

RESUMO - O objetivo do presente trabalho foi selecionar parentais e híbridos de sorgo granífero para características agronômicas. Foram avaliados 184 cruzamentos oriundos de um dialelo parcial envolvendo 16 linhagens macho-estéreis e 12 restauradoras da fertilidade. Foram realizados 8 experimentos, com 23 híbridos cada e duas testemunhas adicionais (BRS 304 e BRS 330), em blocos casualizados, com duas repetições. Foram avaliadas as características rendimento de grãos, florescimento e altura de plantas. Os efeitos de CGC e CEC foram significativos para as três características, mostrando a importância dos efeitos aditivos e dominantes no controle destes caracteres. O quadrado médio para CGC foi superior ao da CEC. Todos os parentais que contribuíram para aumentar o rendimento de grãos também o fizeram para altura de plantas, exceto pelos parentais femininos CMSXS 1006 e CMSXS 1011, mostrando a dificuldade de dissociar estas duas características. Os híbridos mais produtivos apresentaram altura de plantas acima do recomendado para sorgo granífero, mesmo assim foi possível a seleção de cruzamentos que apresentaram rendimento de grãos acima da média, florescimento abaixo da média e altura dentro do padrão exigido. Dentre estes, pode-se destacar os híbridos CMSXS 1002 x CMSXS 1102, CMSXS 1006 x RTx2907, ATx ARG 1 x SC1155 e CMSXS 1008 x Tx2741.Palavras-chave: Sorghum bicolor, seleção de parentais, dialelo, hibridação, melhoramento de plantas. COMBINING ABILITY OF LINES AND SELECTION OF GRAIN SORGHUM HYBRIDS ABSTRACT - The purpose of this work was to select grain sorghum lines and hybrids for growing as succession crop. Crosses, coming from a partial diallel involving 16 male sterile lines and 12 restorer lines, were evaluated. Eight experiments were carried out with 23 hybrids each and two additional checks (BRS 304 and BRS 330) in randomize complete blocks design, with two replications and plot of two lines of five meters long. Grain yield, days to flowering and plant height were evaluated. The effects of GCA and SCA were significant, showing the importance of both additive and dominant effects in the control of these traits. The mean square for GCA was well above the SCA, suggesting the importance of parental selection in sorghum. Only the lines CMSXS 1006 and CMSXS 1011 contributed to rise grain yield without increasing the plant height in the hybrids they compose. The most productive hybrids showed plants above 150 cm, however it was still possible to get crossings that had yield above average, cycle below average and plant height within the standard required for grain sorghum. Among these are the hybrids CMSXS 1002 x CMSXS 1102, CMSXS 1006 x RTx2907, ATX ARG 1 x SC1155 and CMSXS 1008 x Tx2741, with high yields and CEC.Keywords: Sorghum bicolor, parental selection, diallel, hybridization, crop breeding.

Sorghum grain yield can be significantly affected by climatic changes, especially drought and high temperature. The purpose of this study was to evaluate hybrids of grain sorghum grown under normal irrigation conditions or water stress in order to select those likely to be more tolerant of drought. Forty-nine hybrids were grown in a randomized block design experiment, with three replications. The plots consisted of four rows of 5 m length. Grain yield, weight of 1000 grains, harvest index, days to flowering, and plant height were measured. All of these characteristics were affected by water stress; however, grain yield showed the largest relative reduction. Comparison of the various genotypes showed that some hybrids had an acceptable grain yield under water stress, and maintained a high average yield compared to growth without stress. Several hybrids gave better grain yield than commercial check cultivars: 1170090, 1170092, 1170064, 1167026, 1167064, 1170093, 1167008, 1167029, 0009061, 1167092, 1105647, and 1170019 stood out for their acceptable plant height, earliness, and higher productivity.