The sesame crop (Sesamum indicum L.) is sensitive to competition with weeds because of its low competitiveness that is directly linked to its slow initial growth. The control of weeds in the crop is an essential practice to ensure the high productivity of this oilseed. Therefore, to define the critical period of interference prevention is important to ensure efficiency and low control costs. Factors such as cultivar, environmental conditions, and cultivation system may alter the critical weed interference prevention period (CPWC). Therefore, the objective of this work was to determine the critical weed interference prevention period in two sesame cultivars. The critical weed interference prevention period for sesame cultivars, BRS Seda and CNPA G2, was defined in two years (2016 and 2017). Log-logistic regression of four parameters was used to determine the critical weed interference prevention period. The cultivar CNPA G2 was more competitive compared to the cultivar BRS Seda. The CPWC for BRS Seda was on average 67 and 52 days, whereas for CNPA G2 was 52 and 34 days, considering respectively, a loss of 5 and 10%. Weed control for BRS Seda and CNPA G2 should begin respectively between 12 and 15, and 17 and 20 days, considering a loss of 5 and 10%.

RESUMOO pepino é uma hortaliça de grande importância econômica e alimentar, devido a sua apreciação como componente de saladas. No entanto, o seu cultivo no semiárido apresenta risco, devido aos problemas de salinidade, sendo necessária a identificação de cultivares tolerantes, que se desenvolvam melhor em ambientes com problemas de salinidade. Com isso, Objetivou-se avaliar a emergência, o crescimento e a tolerância de cultivares de pepino ao estresse salino. O experimento foi desenvolvido em ambiente protegido (casa de vegetação) localizado no município de Pombal, Paraíba, PB. O estudo foi arranjado em esquema fatorial 2 x 5 um delineamento experimental inteiramente casualizado, constituído de duas cultivares de pepino (C1 -Aopdai e C2-Wisconsin SEM-58) e cinco níveis de salinidade da água de irrigação (0,6 (controle); 1,2; 1,8, 2,4 e 3,0 dS m -1 ) com quatro repetições e dez plantas por parcela. As plantas de pepino foram conduzidas por 20 dias, nos quais se avaliou a emergências de plântulas, o crescimento inicial, o acúmulo de biomassa e o índice de tolerâncias das cultivares com relação ao rendimento de biomassa. A salinidade da água de irrigação afeta a emergência, o crescimento e o acúmulo de massa seca das plantas de pepino. A cultivar Aopdai apresenta os maiores índices de emergência, o crescimento e o acúmulo de massa seca em relação a cultivar Wisconsin SEM-58. A cultura do pepino pode ser irrigada com água salina de até 1,8 dS m -1 durante a sua fase de crescimento inicial. Palavras-chave:Cucumis sativus L., Irrigação, Salinidade.

This study aimed to evaluate the emergence, growth, biomass accumulation and tolerance of peanut genotypes under salt stress. The experiment was conducted in a protected environment (greenhouse), evaluating six peanut genotypes (Tatuí, L7151, Caiapó, IAC8112, IAC881 and Havana), which were subjected to two levels of irrigation water salinity (0.5 [control] and 3.5 dS m-1), arranged in a 6 x 2 factorial scheme, in a randomized block design, with five repetitions, with two plants per plot. Plants were cultivated for 30 days after sowing in lysimeters with capacity for 0.5 dm3, filled with a mixture of non-saline, non-sodic soil and commercial substrate in 1:1 proportion on volume basis. During this period, plants were evaluated for emergence, growth, biomass accumulation, tolerance to salinity and dissimilarity. The genotypes Tatuí and L7151 are the most sensitive to salt stress in the emergence stage. Irrigation with high-salinity water reduced the growth and biomass accumulation of the peanut genotypes, and Caiapó and IAC8112 were the least affected. The classification of salinity tolerance had the following sequence: Caiapó > IAC8112 > Havana > Tatuí > IAC881 > L7151.

No abstract

Beetroot (Beta vulgaris L.) is a tuberous vegetable that is under experimentation in the vegetable production system in Rio Grande do Norte state (Brazil). It is quite demanding, in nutritional terms. One of the alternatives to meet this need is green manuring using spontaneous species of the Caatinga biome. The aim of the present work was to optimize the agro-biological performance and economic profitability of the beetroot 'Early Wonder', fertilized with different doses of hairy woodrose (Merremia aegyptia (L.) Urb.) in this semi-arid environment. Hairy woodrose is a spontaneous species of the Caatinga biome that is widely distributed, being found in forests, fences, forest clearings and fields, growing in soils of different textures, producing biomass with a high content of macronutrients. This material was collected from spontaneous vegetation, native to the region, and used as green manure.The experimental design was a randomized complete block, with four treatments and five replicates. The treatments consisted of four amounts of hairy woodrose biomass incorporated into the soil (10, 25, 40 and 55 t ha-1 of dry matter). The following agronomic characteristics were evaluated in each beetroot treatment: plant height, fresh mass of shoots, number of leaves per plant, dry mass of shoots and dry mass of roots, total and commercial root productivity, and root productivity classified into scrap and extra roots, extra A roots, extra AA and great roots. Apart from these characteristics, the following economic indicators were also determined for each treatment: gross income, net income, rate of return and profit margin. The maximum agro-biological efficiency of beet root productivity (22.68 t ha-1) was obtained from 44.92 t ha-1 of hairy woodrose biomass added to the soil. The maximum economic efficiency of the yield of beet roots was achieved as a net income of AU$2,491.00 (R$6,406.36) ha-1, provided by the production of 22.04 t ha-1 of commercial roots, using 37.03 t ha-1 of hairy woodrose biomass incorporated into the soil. The use of hairy woodrose as green manure presents agro-economic feasibility in beet cultivation in this semi-arid environment.