Selection of drought tolerant wheat genotypes for Arid and Semi-arid lands (ASALS) of Kenya, which consist of 83% of total land area, can provide alternative agricultural land for expansion. To reduce cost of dryland research, simulated drought under a rain shelter offers a good alternative for screening because marginal areas are vast and widespread. Four moisture regimes which simulated terminal, early, mid-and late-season droughts were created under the mobile rain shelter at Njoro in 1998/99, by applying drip irrigation (i) up to seedling stage (70 mm) (ii) through tillering (82 mm) (iii) up to anthesis (94 mm) and (iv) grain filling (106 mm), respectively, to determine drought responses of five wheat varieties (Duma, R748, R830, R831 and R833) and identify drought tolerant genotypes. Control watering regime had 118 mm applied at all stages. Yield and yield components in each season and the two seasons combined showed significant difference (P<0.05 and 0.01, respectively). Early drought during seedling stage and tillering caused significant reduction in plant heights, tiller number and number of reproductive tillers. However, drought from anthesis and grain filling to maturity caused significant (P<0.05) reduction in ear length (16.9%), spikelets/head (14.3%), 1000-kernel weights (22.4%) and an increase in the number of sterile florets/head (28.3%), compared to control. Seedling and reproductive stage (anthesis and grain filling) droughts caused the highest grain yield reduction (25 and 67%, respectively), indicating that they were the most critical stages in moisture requirement compared to control. Genotype R748 out-performed Duma (check) in all moisture regimes, and was recommended for field testing and participatory evaluation. From this study, it is possible to select drought tolerant cultivars using mobile rain shelters by drought simulations in Kenya.Key Words: Duma, irrigation, dryland, moisture stress RÉSUMÉLa sélection des génotypes tolérant a la sécheresse pour les terres arides et semi-arides (ASALS) du Kenya, lesquelles consistent a 83% de la surface de terre, peut pourvenir de terre pour l'expansion agricole. Pour réduire le coût de la recherche dans les régions arides, la sécheresse simulée a l'abris de la pluie offre une bonne alternative pour la sélection parce que les aires marginales sont vastes et éparpillées. Pour les régimes humides qui sont simulés a l'état terminal, matinal, en pleine et en retard des saisons séches étaient crées sous un abri mobile a Njoro entre 1998/1999, par application de l'irrigation par goutte 1) jusqu'a l' étape de semis (70 mm) ii) a travers le labourage (82 mm), iii) jusqu'a l'étape d'anthere (94 mm) et iv) graine nourrissante (106 mm), respectivement pour déterminer les réponses a la sécheresse aux cinq variétés de blé (Duma, R748, R830, R831 et R833) et identifier les génotypes tolérant la sécheresse. Le contrôle du régime en eau avait 118 mm appliqués a toutes les étapes. Les composants de la production et du rendement dans chaque saison et les deu...

The effects of weeds on coffee productivity and the methods used for their control are discussed. The more common weeds are listed, together with the control methods that can be used at various phases of coffee production. Malezasy control de las mismas en el cafe'RESUMEN Se discuten los efectos de las malezas en la productividad del cafe, y los metodos utilizados para su control. Se detallan las malezas mas comunes, junto con los metodos de control que se pueden utilizar en las diversas fases de la production de cafe.

Coffee quality is a parameter influenced by a wide range of factors. The criteria used to measure quality include raw bean size and shape as well as colour; roast bean appearance is measured by visual scoring. Cup quality is determined by organoleptic means. Samples are submitted to professional coffee tasters who assess body, acidity, flavour and general standard while off-flavours are distinguished. Owing to the role of quality in the pricing of coffee, it is important that coffee should be handled carefully at the farm and factory level. At all these levels, the recommended procedures of handling coffee should be adhered to, in order to obtain top quality coffee. Some of these procedures are discussed in the paper.

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The effects of intercropping young plants of the compact arabica coffee hybrid cultivar Ruiru 11 with potatoes, tomatoes, maize and Phaseolus (dry) beans were studied between 1987 and 1989 at Ruiru in Kenya. Yields of clean (hulled) coffee were reduced by the maize intercrop by 59-100%. Coffee bean size, and raw, roast and liquor quality were not significantly affected by the potato, tomato and bean intercrops, which gave positive net economic benefits. Potatoes planted between all the coffee rows gave the largest marginal rate of economic return, followed by tomatoes in combination with beans. The technically and economically viable intercrops for coffee were potatoes, tomatoes, beans, and tomatoes in combination with beans. Siembra simultdnea de cafe Arabicay cultivospara la alimentacidn RESUMENEntre 1987 y 1989, en Ruiru, Kenia, se estudiaron los efectos de la siembra simultanea de plantas jovenes de la variedad de cultivo hfbrida compacta de cafe Arabica, Ruiru 11, y papas, tomates, maiz y porotos Phaseolus (secos). El rendimiento de cafe limpio (sin la vaina) se redujo en un 59-100% con la siembra simultanea con maiz. El tamafio del grano de cafe, y la calidad del grano crudo, tostado, o del Hcor, no se vieron afectados en forma significativa por la siembra simultanea con papa, tomate y poroto, lo cual produjo un beneficio economico neto positive Las papas plantadas entre las hileras de cafe produjeron el mayor indice marginal de utilidades economicas, seguidas por los tomates en combinacion con los porotos. Los cultivos simultaneos tecnica y economicamente viables para el cafe fueron las papas, tomates, porotos, y tomates en combinacion con porotos.