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Not AvailableEffective weed management is important for a successful wheat production. Inadequate weed control can lead to significant yield loss and harvest problems. One of the pre-requisite of efficient weed management is proper weed identification so that suitable strategies are selected. An Expert System on Wheat Crop Management has been developed by ICAR-IASRI, New Delhi with the collaboration of ICAR-IARI, New Delhi, ICAR-IIDWR. Karnal and ICAR-NCIPM, New Delhi. This system has a crop protection module that carries a sub module on weed management. The module helps in identifying weeds and suggests treatment to minimize the production loss. The system carries information of about 23 major weeds affecting wheat crop and its management stored in its knowledge base. The system works as an information bank for wheat growing farmers that can help them in better crop management in order to enhance productivity and production of wheat in the country. The system is available at the URL http://www.iasri.res.in/wheatNot Availabl

Períodos de interferência de plantas daninhas na cultura da mandioquinha-salsa Periods of weed interference in Peruvian carrot crop

A mandioquinha-salsa é normalmente cultivada em espaçamentos largos e a emergência das plantas e o crescimento inicial são lentos, favorecendo o surgimento de plantas daninhas e onerando o custo de produção. Este trabalho teve como objetivo determinar os períodos de interferência de plantas daninhas - período crítico de prevenção da interferência (PCPI), período anterior à interferência (PAI) e período total de prevenção da interferência (PTPI) - na cultura da mandioquinha-salsa, clone 'Amarelo de Carandaí', cultivada no espaçamento de 1,0 x 0,4 m, no período de maio de 2001 a abril de 2002. Os tratamentos foram constituídos por dois grupos de controle: em um manteve-se a cultura na ausência das plantas daninhas em períodos iniciais após o plantio das mudas e, em outro, a cultura foi mantida na presença das plantas daninhas em períodos iniciais após o plantio. Os períodos estudados foram: 0, 21, 42, 63, 84, 105, 126, 147, 168, 189, 210 e 315 dias após o plantio (DAP), totalizando 24 tratamentos, que foram dispostos em blocos casualizados, com quatro repetições. O PCPI de plantas daninhas na cultura da mandioquinha-salsa, considerando as perdas de raízes comerciais de 5% como aceitáveis, localizou-se entre o 58º e o 120º DAP. A interferência das plantas daninhas reduziu em 98% a produtividade de raízes comerciais quando a cultura conviveu com as plantas daninhas por todo o ciclo. O PAI foi de 58 dias; o PTPI, de 120 dias; e o PCPI, de 58 a 120 dias.<br>Peruvian carrot is usually cultivated in wide row spacings and plant emergence and initial growth are slow, favoring weed growth and increasing production cost. The objective of this work was to establish the following periods of weed interference: critical period of interference prevention, period previous to interference and total period of interference prevention in Peruvian carrot, yellow clone, cultivated in a 1.0 x 0.4 m spacing from May, 2001 to April, 2002. The treatments consisted of two control groups: weed-free crop during the initial period after planting, and crop kept with weeds during the initial period after planting. The periods studied were: 0, 21, 42, 63, 84, 105, 126, 147, 168, 189, 210 and 315 days after planting (days after planting), totaling 24 treatments, arranged in a randomized block design, with four replications. Considering a 5% reduction in yield of commercial roots as acceptable, weed critical period of interference prevention in Peruvian carrot culture was between 58 and 120 DAP. Weed interference reduced commercial root yield in 98% when the crop was kept with weeds over the whole cycle. Therefore, period previous to interference was period 58 days, total period of interference prevention , 120 days and critical period of interference prevention, between 58 and 120 days