Fator De Resposta Produtiva De Mombaça E Marandu Ao Déficit Hídrico

Abstract

O objetivo com este estudo foi compreender o efeito da disponibilidade hídrica sobre a produtividade no capim-mombaça [Megathyrsus maximus (Jacq.) B. K. Simon & S. W. L. Jacobs] e capim-marandu [Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster], determinando o coeficiente de resposta ao déficit hídrico (ky). O experimento foi avaliado em delineamento de blocos ao acaso, com duas forragens e três repetições. O período experimental correspondeu a doze ciclos de crescimento com intervalos fixos de colheita (28 dias para a estação chuvosa e 42 dias para a estação seca). Os ky foram determinados com base nos dados de produção real e potencial das forrageiras, bem como nos dados de evapotranspiração real e máxima. Para ambas as forragens, o acúmulo de forragem (AF) foi maior no outono e menor no inverno (5310 e 626 kg de matéria seca ha-1, respectivamente). Na média das quatro estações, o AF para capim-marandu foi 21,3% maior que o capim-mombaça (3344 vs. 2756 kg matéria seca ha-1, respectivamente). Para o capim-mombaça, o ky foi de 1,05, indicando sensibilidade média a alta ao déficit hídrico. No entanto, o ky foi de 0,63 para o capim-marandu, o que representa baixa sensibilidade ao déficit de água do solo.Palavras-chave: Brachiaria; coeficiente de sensibilidade; Megathyrsus; tolerância a seca. YIELD RESPONSE FACTOR OF MOMBAÇA GUINEA GRASS AND MARANDU PALISADE GRASS TO WATER DEFICIT ABSTRACT: The objective with this research was to understand the effect of water availability on Mombaça guinea grass [Megathyrsus maximus (Jacq.) B. K. Simon & S. W. L. Jacobs] and Marandu palisade grass [Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster] productivity, determining the yield response factor to water deficit (ky). The experiment was evaluated in a randomized block design with two forages and three replicates. The experimental period corresponded to twelve growth cycles with fixed harvest intervals (28 days for the rainy season and 42 days for the dry season). The ky were determinate based on the data of real and potential yield of grasses, as well as the data of real and maximum evapotranspiration. To both grasses, herbage accumulation (HA) was greatest in the autumn and leats in the winter (5310 and 626 kg dry matter ha-1, respectively). On average of the four seasons, the HA for Marandu palisade grass was 21.3% higher than Mombaça guinea grass (3344 vs 2756 kg dry matter ha-1, respectively). For Mombaça guinea grass, ky was 1.05, indicating medium to high sensitivity to water deficit. However, the ky was 0.63 for Marandu palisade grass, which represents low sensitivity to soil water deficit.Keywords: Brachiaria; drought tolerance; Megathyrsus; sensitivity coefficient.

Irrigation management, light interception, and nitrogen in Tanzania grass cultivation

“…The increase in stem height observed in the present study, due to the increase in irrigation depth, has also been observed by Lopes et al (2014), Luz et al (2008) and Alencar et al (2009), when studying grasses of the genera Brachiaria (Xaraés grass), Panicum (Tanzania grass and Mombaça grass), Pennisetum (Pioneiro grass), and Cynodon (Estrela grass), respectively. Tropical forage species are efficient in using water, which implies greater production potential (MOMBACH et al, 2019).…”

“…Greater availability of water favors the absorption, solubilization and transport of nutrients in plants, resulting in increments in the structural characteristics of forage species (LIMA et al, 2018;COUTINHO et al, 2020;MOMBACH et al, 2019;ARAÚJO JÚNIOR et al, 2019;BRANDÃO et al, 2017). However, the linear increase in stem height as a function of increasing irrigation depths should be carefully evaluated, as stem height restricts intake by cattle due to the physical barrier it imposes on the grazing process.…”

“…The use of increasing irrigation depths has promoted higher yields of leaf fresh and dry mass, number of tillers and height of the grass (LEMOS et al, 2019). When the availability of irrigation water is lower than the volume required by forage species, it causes a reduction in the structural characteristics and nutritional value of pastures (MOMBACH et al, 2019;COUTINHO et al, 2020). However, information on management strategies for Tanzania grass under deficit irrigation, such as the association of nitrogen fertilization management and light interception, is scarce in the literature.…”

Tolerância de híbridos de braquiária ao estresse hídrico

“…Das braquiárias, observa-se na Brachiaria brizantha cv. Marandu baixa sensibilidade ao déficit hídrico (Mombach et al, 2019), o que faz deste capim uma referência para diferimento da pastagem. Contudo, este capim tem sérios problemas em solos encharcados, visto que é acometido por fungos, como Fusarium spp.…”