-The goal of this study is to characterize the weed phytosociology in some major erect and prostrate cowpea cultivars in Brazil, in the Northern growing conditions of Minas Gerais state. The test was conducted in Janaúba, Minas Gerais state. The treatments consisted in five erect cultivars (BRS Guariba, BRS Tumucumaque, BRS Novaera, BRS Itaim and BRS Cauamé) and four prostrate ones (BRS Marataoã, BRS Pajeú, BRS Pujante and BRS Xiquexique). The plots were composed of four five meter rows, spaced 0.5 m apart, for erect cultivars and 1.0 m for the prostrated ones. Weed sampling was performed 50 days after sowing by standard Square Method. The species were identified and quantified, and then dried at 65 o C for 72 hours and weighed. The frequency, absolute and relative density and abundance, the importance value index (IVI) and the similarity index were evaluated. In the erect cultivars, the Amaranthaceae, Euphorbiaceae, Asteraceae and Convolvulaceae families stood out with higher IVI's. In prostrate cultivars, the Amaranthaceae, Asteraceae and Malvaceae families stood out. Portulaca oleracea and Amaranthus spp. were the species with the highest IVI. The similarity index between erect and prostrate cultivars was 72%; nine of the 16 families occurred in both cultivars. BRS Tumucumaque, erect, and BRS Pujante, prostrate had lower weed infestation.Keywords: Vigna unguiculata, phytosociological, plant habit, weeds. RESUMO -Objetivou

In the current scenario of climate change, sorghum crop has high growth potential, requiring adaptation and selection studies for the various Brazilian production environments. Sorghum is among the most drought-tolerant cereals; however, extended summer can reduce the size and number of grains in the plant, reflecting into poorer yields. Sorghum breeding programs aim to develop hybrids more tolerant to water deficit, to ensure profitable yield even in the face of drought stress. The objective of the present study was to evaluate the effects of water restriction on grain sorghum hybrids in the pre-and post-flowering phases in the Brazilian semiarid. Twenty-five hybrids were evaluated under controlled irrigation conditions in Nova Porteirinha-MG and Teresina-PI. In the Nova Porteirinha, the hybrids were cultivated under conditions of non-drought stress and with drought stress in pre-and post-flowering stage. On the other hand, in Teresina, the experiment took place with non-drought stress and drought stress at post-flowering stage. The experimental design was in randomized complete blocks, in factorial scheme, with three replications. Drought stress reduced grain yield by more than 40%, showing that even being resistant, sorghum is affected by drought. Hybrids 1168093, 1167092, 1236020 and 1423007 showed high yields in the various environments, outyielding the commercial controls, what allows the recommendation of these cultivars for the semiarid areas or late off-season in the Cerrado region.

-The objective of this paper was to characterize the phytosociology of weeds in function of different types of growth of common bean cultivars in the North of Minas Gerais. The study was conducted in the experimental area, located in the municipality of Janaúba, MG. The treatments consisted of eight commercial cultivars of common beans with different types of growth. The design was done in randomized blocks, with three replications. The soil preparation was conventional and the planting was done in June, with manual seeders, with a 0.5 m spacing between rows. The phytosociological survey was performed in two phases of bean cultivation, in stages V3 and R8. The method used was the square inventory one, with a 0.25 m 2 frame, randomly released once in each plot. Samples of each square were identified and quantified by family, genus and species, and the sampled plants were collected with their complete structure. Next, the material was sent to a drying greenhouse with forced air circulation at 65 o C for 72 hours, for drying and determination of weight of dry matter. We also estimated the Relative Frequency, Relative Density and Relative Abundance to determine the importance value index and similarity index. At the V3 stage, the species Sorghum halepense, Brachiaria plantaginea and Boerhavia diffusa had higher importance value indexes. At the R8 stage, the Amaranthus viridis specie showed higher importance value index and dry matter. In more prostrate cultivars, the weeds present lower importance value indexes at the R8 stage.

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.

Drought stress is a serious obstacle for crop production, especially in arid and semi-arid areas of the world. Sorghum is a useful crop to grow in areas with erratic, poorly distributed or inadequate rainfall. To help determine the best alternatives, we evaluated 30 sorghum cultivars with and without water stress in the post-flowering plant stage. The work was carried out at the Experimental Station of Gorutuba, in Nova Porteirinha, MG, Brazil, during 2013 and 2014 seasons. The experimental design was a randomized complete block, with three replications and two water regimes. The traits evaluated were grain yield, number of days to flowering, plant height and 1,000 grain mass. Water restriction reduced the grain yield by 68.9% in 2013, 31.2% in 2014 and 50.1% in the average of the two years. The genotypes with best grain yield stability were B.Tx635, SC 720 and BR012RxSC566. Water stress significantly reduced plant height and grain mass.