O ensaio foi conduzido no Campo Experimental de Coronel Pacheco MG, no período de 07 de outubro de 2003 a 06 de janeiro de 2005, a fim de avaliar o efeito de quatro doses de nitrogênio (100, 300, 500 e 700 kg/ha de N) e seis lâminas de água (0, 20%, 40%, 80%, 100% e 120% da evapotranspiração) sobre a produção de matéria seca, densidade populacional de perfilhos basais, altura das plantas, percentagem de solo coberto por plantas de capim-elefante (Pennisetum purpureum, Schum), teor de proteína bruta, teor de FDN e DIVMS das plantas de capim-elefante durante os períodos seco e chuvoso. As doses de nitrogênio constituíram as parcelas e as lâminas de água as subparcelas, segundo o delineamento em blocos casualizados com quatro repetições. A dimensão de cada subparcela experimental foi de 3 m de largura e 6 m de comprimento, com área de 18 m2. Cada parcela experimental foi formada pelas seis lâminas de água, medindo 6 m de largura por 18 m de comprimento, com área de 108 m2, onde foram aplicadas as doses de nitrogênio 100, 300, 500 ou 700 kg/ha de N. Como fonte de adubo nitrogenado, utilizou-se a uréia, aplicada a lanço, parcelada em seis aplicações durante o período experimental. As irrigações foram efetuadas de acordo com a umidade do solo a 60 cm de profundidade, a qual era monitorada semanalmente, por meio de tensiômetros, dispostos estrategicamente na área experimental, em todas as repetições, na parcela que recebeu 300 kg/ha de N e subparcela irrigada com 100 % da evapotranspiração. Quando o capim-elefante atingiu 1,60 m em uma das parcelas, foi colhida uma amostra de forragem em cada subparcela. A produção de matéria seca acumulada no ano experimental e durante o período chuvoso aumentou linearmente tanto em relação às doses de N quanto às lâminas de água aplicadas. Durante o período seco, a produção do capim-elefante aumentou linearmente com as doses de N, mas teve um comportamento quadrático com as lâminas de água aplicadas. A contribuição do período seco para a produção acumulada de matéria seca (kg/ha) do ano todo não alterou muito entre os tratamentos sem irrigação e com irrigação, mostrando que está técnica não alterou a estacionalidade da produção do capim-elefante. Foi observada resposta linear da altura das plantas de capim-elefante em função das doses de N aplicadas e em função das lâminas de água aplicadas tanto no ano experimental, quanto nos períodos seco e chuvoso. A cobertura do solo pelas plantas de capim-elefante durante o ano experimental sofreu influência linear somente das lâminas de água aplicadas, não respondendo às doses de N. No período seco não houve resposta à aplicação de adubo nitrogenado, sendo a cobertura do solo pelas plantas de capim-elefante influenciada de forma quadrática pelas lâminas de água aplicadas. Já no período chuvoso a cobertura do solo pelas plantas de capim-elefante não sofreu influência da adubação nitrogenada nem das lâminas de água aplicadas. Durante o ano experimental e durante o período seco, o número de perfilhos basais emitidos pelas plantas de capim-elefante aumentou linearmente com as doses de N e lâminas de água aplicadas, e durante o período chuvoso sofreu influência linear das lâminas de água aplicadas, não respondendo à adubação nitrogenada. O teor de proteína bruta das lâminas foliares mais pseudocolmo das plantas de capim-elefante aumentou linearmente com as doses de N tanto no ano experimental quanto nos períodos seco e chuvoso, não sendo influenciado pelas lâminas de água aplicadas. O teor de fibra em detergente neutro nas lâminas foliares mais pseudocolmo das plantas de capim-elefante foi influenciado negativamente pelas doses de N durante o ano experimental e no período seco, sendo influenciado positivamente pelas lâminas de água aplicadas no período chuvoso. O teor de digestibilidade in vitro da matéria seca das lâminas foliares mais pseudocolmo das plantas de capim-elefante respondeu de forma quadrática ao aumento das doses de N apenas no ano experimental e no período seco, não sendo influenciado pelas lâminas de água aplicadas. No período seco a DIVMS não foi influenciada por nenhuma das variáveis estudadas. | The research was conducted at the Experimental Field of Coronel Pacheco MG, from October 7th, 2003 to January 6th, 2005, in order to evaluate the effects of four doses of nitrogen (100, 300, 500 e 700 kg/ha of N) and six water sheet (0, 20%, 40%, 80%, 100% e 120% of evapotranspiration) over the production of dry matter, populational density of basal tiller, plants height, percentage of soil covered by elephant grass plants (Pennisetum purpureum, Schum), crude protein and NDF tenors, and IVDMD of elephant grass plants during the dry and rainy periods. The nitrogen doses were the plots and the water sheet constituted the subplots, according to the complete randomized blocks experiment with four repetitions. The size of each experimental subplot was 3 m wide and 6 m long, with an area of 18 m2. Each experimental plot was formed by six water sheet, measuring 6 m wide by 18 m long, with an area of 108 m2, in which the doses of nitrogen 100, 300, 500 or 700 kg/ha of N were applied. As the source of nitrogenized compost, urea was used, manually thrown, divided into six applications during the experimental period. The irrigations were conducted according to the soil humidity at 60 cm deep, which was monitored weekly, using a tension meter, placed strategically in the experimental area, in every repetition, in the plot which received 300 kg/ha of N and subplot irrigated with 100% of evapotranspiration. When the elephant grass reached 1, 60 m in one of the plots, it was harvested one sample of fodder from each subplot. The production of dry matter accumulated in the experimental year and during the rainy period increased linearly as much as related to the doses of N as related to the applied water sheets. During the dry period, the production of elephant grass increased linearly with the doses of N, but it had a quadratic behavior with the applied water sheets. The contribution of the dry period to the accumulated production of dry matter (kg/ha) of the entire year did not differ much between the treatments without irrigation and with irrigation, demonstrating that this technique did not alter the seasonal growth of the elephant grass production. It was observed a linear response of the elephant grass plant height related to the doses of N applied and related to the applied water sheets as much as in the experimental year, as in the dry and rainy periods. The soil covered by the elephant grass plants suffered linear influence just from the applied water sheets during the experimental year, not responding to the doses of N. In the dry period, there was no response to the application of doses of N, but the soil covered by the elephant grass plants were influenced in a quadratic way by the applied water sheets. In the rainy period, the soil covered by the elephant grass plants did not suffer any influence either by the doses of N or by the applied water sheets. During the experimental year and during the dry period, the amount of basal tillers released by the elephant grass plants increased linearly with doses of N and the applied water sheets, and during the rainy period suffered linear influence from the applied water sheets, not responding to the doses of N. The crude protein tenor of the leaves blade plus pseudoculm of the elephant grass plants increased linearly with the doses of N as much as in the experimental year as in the dry and rainy periods, not being influenced by the applied water sheets. The neutral detergent fiber tenor in the leaves blade plus pseudoculm of the elephant grass plants was negatively influenced by the doses of N during the experimental year and in the dry period, being positively influenced by the applied water sheets applied in the rainy period. The in vitro dry matter digestibility of the leaves blade plus pseudoculm of the elephant grass plants responded in a quadratic way to the increase of the doses of N just in the experimental year and in the dry period, not being influenced at all by the applied water sheets. The IVDMD was not influenced by any of the studied variables in the dry period. | Conselho Nacional de Desenvolvimento Científico e Tecnológico

Resumen La poca disponibilidad de agua observada en las presas del país y la sobreexplotación de los acuíferos subterráneos hacen urgente nuevas estrategias para optimizar este recurso. Una estrategia es la optimización del riego mediante el cálculo de las necesidades hídricas para la programación de riegos. El objetivo del este estudio fue analizar la relación entre la evapotranspiración de cultivo (ETc) y coeficiente del cultivo (Kc) en el cultivo del tomate en función del número de tallos, para el suministro el agua de riego a partir de un lisímetro de drenaje y el atmómetro. El trabajo se realizó en condiciones controladas usando tezontle como sustrato y un sistema de riego por goteo. El experimento consistió en tres tratamientos, uno (T1), dos (T2) y tres (T3) tallos por planta. Se utilizó el método del lisímetro de drenaje para medir la transpiración diaria de cultivo (ETc) y un atmómetro para estimar la evapotranspiración de referencia (ETo). La transpiración acumulada del cultivo fue de 352, 389 y 434 mm para T1, T2 y T3 y un kc de 1.06, 1.16 y 1.32 para los mismos tratamientos respectivamente, así como el requerimiento de riego de 1.04, 1.14 y 1.29 L planta-1, ambos parámetros determinados en la etapa de máxima demanda hídrica y nutrimental. Se concluye que las mediciones diarias de traspiración en tomate con el lisímetro de drenaje permiten calcular el requerimiento hídrico de los cultivos, además, el atmómetro es una alternativa para estimar la ETo con fines de calendarización del riego en diferentes cultivos. | Abstract The low availability of water observed in the country’s dams and the overexploitation of underground aquifers make it urgent to generate strategies to optimize this resource. One strategy is the optimization of irrigation by calculating water needs for irrigation scheduling. The objective of this study was to analyze the relationship between crop evapotranspiration (ETc) and crop coefficient (Kc) in tomato cultivation as a function of the number of stems, for the supply of irrigation water based on a drainage lysimeter and an atmometer. The work was carried out under controlled conditions using tezontle as a substrate and a drip irrigation system. The experiment consisted of three treatments, one (T1), two (T2) and three (T3) stems per plant. The drainage lysimeter method was used to measure daily crop transpiration (ETc) and an atmometer was used to estimate reference evapotranspiration (ETo). The accumulated transpiration of the crop was 352, 389 and 434 mm for T1, T2 and T3 and a Kc of 1.06, 1.16 and 1.32 for the same treatments, respectively, as well as the irrigation requirement of 1.04, 1.14 and 1.29 L plant-1, both parameters determined in the stage of maximum water and nutrient demand. It is concluded that the daily measurements of transpiration in tomato with the drainage lysimeter allow to reliably calculate the water requirement of crops, in addition, the atmometer is an alternative to estimate the ETo for irrigation scheduling purposes in different crops.

En la Comarca Lagunera de los estados de Coahuila y Durango, México. La disponibilidad del agua constituye una de las mayores limitantes para la producción de forrajes. En el periodo de otoño - invierno se establecen los cultivos de zacate ballico (Lolium multiflorum), trébol (Trifolium) y avena (Avena sativa L). Sin embargo, por la poca disponibilidad del agua durante este periodo, existe el interés de mejorar la productividad del agua mediante el establecimiento de nuevos cultivos. El triticale ha demostrado ser una especie competitiva con el zacate ballico, trigo (Triticum spp.), cebada (Hordeum vulgare), centeno (Sécale cereale) y ryegrass (Lolium). Además, posee las cualidades nutritivas y puede sustituir a la avena, sobre todo en regiones con bajas temperaturas. El objetivo del estudio fue evaluar la productividad del agua en el cultivo de triticale y estimar la producción de materia seca en función del índice de área foliar (IAF). El establecimiento del cultivo fue en dos periodos de otoño-invierno, en los años 2011 y 2012 en la pequeña propiedad Campo sagrado ubicada en el km 9.5 de la carreteara Torreón-Mieleras. La productividad del agua (PA) fue de 1.08 g m-2 mm-1 y de 1.3 g m-2 mm-1 en los periodos evaluados. La producción de materia seca (MS) fue estimada mediante un modelo de tipo lineal MS= 50.86 IAF - 19.68 y R²= 0.90. El agua aplicada fue de 520 y 620 mm en cada ciclo, con rendimientos de 566 y 807 g m-2. | In the Comarca Lagunera from the states of Coahuila and Durango, Mexico; water availability is one of the major constraints for fodder production. During autumn - winter grass ryegrass (Lolium multiflorum), clover (Trifolium) and oats (Avena sativa L.) are established. However, the limited availability of water during this period, there is interest in improving water productivity by establishing new crops. Triticale has proven to be a competitive species with wheat (Triticum spp.), barley (Hordeum vulgare), rye (Secale cereale) and ryegrass (Lolium). It also has the nutritional qualities and can replace oats, especially in regions with low temperatures. The aim of the study was to evaluate water productivity in triticale and estimate dry matter production based on leaf area index (LAI). The crop was established during two cycles in autumn-winter 2011 and 2012 in a small property from Campo Sagrado located at Km 9.5 on the Torreon-Mieleras road. Water productivity (PA) was 1.08 g m-2 mm-1 and 1.3 g m-2 mm-1 in the evaluated period. The production of dry matter (MS) was estimated using a linear model MS= 50.86 IAF - 19.68 and R²= 0.90. Water applied was 520 and 620 mm in each cycle with yields of 566 and 807 g m-2.

In the Comarca Lagunera from the states of Coahuila and Durango, Mexico; water availability is one of the major constraints for fodder production. During autumn - winter grass ryegrass (Lolium multiflorum), clover (Trifolium) and oats (Avena sativa L.) are established. However, the limited availability of water during this period, there is interest in improving water productivity by establishing new crops. Triticale has proven to be a competitive species with wheat (Triticum spp.), barley (Hordeum vulgare), rye (Secale cereale) and ryegrass (Lolium). It also has the nutritional qualities and can replace oats, especially in regions with low temperatures. The aim of the study was to evaluate water productivity in triticale and estimate dry matter production based on leaf area index (LAI). The crop was established during two cycles in autumn-winter 2011 and 2012 in a small property from Campo Sagrado located at Km 9.5 on the Torreon-Mieleras road. Water productivity (PA) was 1.08 g m-2 mm-1 and 1.3 g m-2 mm-1 in the evaluated period. The production of dry matter (MS) was estimated using a linear model MS= 50.86 IAF - 19.68 and R²= 0.90. Water applied was 520 and 620 mm in each cycle with yields of 566 and 807 g m-2. | En la Comarca Lagunera de los estados de Coahuila y Durango, México. La disponibilidad del agua constituye una de las mayores limitantes para la producción de forrajes. En el periodo de otoño - invierno se establecen los cultivos de zacate ballico (Lolium multiflorum), trébol (Trifolium) y avena (Avena sativa L). Sin embargo, por la poca disponibilidad del agua durante este periodo, existe el interés de mejorar la productividad del agua mediante el establecimiento de nuevos cultivos. El triticale ha demostrado ser una especie competitiva con el zacate ballico, trigo (Triticum spp.), cebada (Hordeum vulgare), centeno (Sécale cereale) y ryegrass (Lolium). Además, posee las cualidades nutritivas y puede sustituir a la avena, sobre todo en regiones con bajas temperaturas. El objetivo del estudio fue evaluar la productividad del agua en el cultivo de triticale y estimar la producción de materia seca en función del índice de área foliar (IAF). El establecimiento del cultivo fue en dos periodos de otoño-invierno, en los años 2011 y 2012 en la pequeña propiedad Campo sagrado ubicada en el km 9.5 de la carreteara Torreón-Mieleras. La productividad del agua (PA) fue de 1.08 g m-2 mm-1 y de 1.3 g m-2 mm-1 en los periodos evaluados. La producción de materia seca (MS) fue estimada mediante un modelo de tipo lineal MS= 50.86 IAF - 19.68 y R²= 0.90. El agua aplicada fue de 520 y 620 mm en cada ciclo, con rendimientos de 566 y 807 g m-2.