Para a determinação do volume de água retido no solo e disponível às plantas, é imprescindível quantificar o teor de água do solo (TAS) na capacidade de campo (CC) e no ponto de murcha permanente (PMP). O objetivo deste trabalho foi comparar os valores do TAS na CC e no PMP determinados por distintos métodos. Utilizaram-se amostras de um Latossolo Vermelho. A CC foi obtida no campo com o método do perfil instantâneo e, no laboratório, com funis de placa porosa. O PMP foi determinado, em laboratório, como sendo o teor de água residual retida no potencial matricial de -1,5 MPa, em câmara de Richards e com medidor de potencial de ponto de orvalho WP4 PotentiaMeter. Para murcha das plantas, o TAS foi significativamente menor no método fisiológico que o determinado nas câmaras de Richards; entretanto, o teor de água do solo no PMP foi estatisticamente igual para a cultura do girassol e superior para o milho, quando comparado com aquele obtido pelo WP4. A água disponível diminuiu com o aumento na tensão para a estimativa da CC e com o método WP4, mas não diferiu do método fisiológico. Assim, o WP4 permitiu adequada estimativa do PMP e disponibilidade hídrica às plantas, em solo argiloso.<br>To estimate available soil water to plants it is necessary to measure field capacity (FC) and permanent wilting point (PWP). The objective of this study was to compare soil moisture at FC and PWP measured by different methods. The soil used was a tropical Oxisol (Haplorthox). The FC was measured under field conditions, using the internal drainage method and in laboratory using porous plate funnel. The PWP was quantified in laboratory as the soil moisture at -1.5 MPa matric potential measured by pressure plate apparatus (Richards chamber) and by WP4 dewpoint Potentia Meter. The physiological PWP was measured using corn and sunflower plants, when they had three leaf pairs and showed irreversible wilting. The soil moisture for PWP based on the physiological method was smaller than soil moisture measured with the pressure plate apparatus; however, soil moisture for sunflower wilting was similar while for corn it was greater than that obtained with the WP4. The available water decreased with increase in water tension considered for estimating FC and with the WP4 method, but similar to one quantified with the physiological method. Thus, the WP4 allowed for adequate estimation of PWP and available water to plants in a clay soil.

This research was carried out in Villaflores and Villa Corzo, located in Chiapas State of Mexico. Specifically, throughout an ethno-agronomical approach, semi-structured interviews were designed and applied to the chayote producers who were selected by random routes. The results indicate the 57.89% of chayote producers in both municipalities, have allowed to control weeds in their crops, and being a higher proportion represented by Villaflores. Given these concerns, they prefer to control weeds throughout traditional methods, basically using mattocks with frequencies of 15 to 30 days after sowing or two to four times per cycle of crop production. Both pest and diseases are mainly controlled throughout chemical methods application. A preference to perform control among periods of higher rainfall or drought is not distinguished. A considerable percentage, which reaches 44% of the interviewed population among both municipalities, report they do not need to control pests and crop diseases.

Abstract This research was carried out in Villaflores and Villa Corzo, located in Chiapas State of Mexico. Specifically, throughout an ethno-agronomical approach, semi-structured interviews were designed and applied to the chayote producers who were selected by random routes. The results indicate the 57.89% of chayote producers in both municipalities, have allowed to control weeds in their crops, and being a higher proportion represented by Villaflores. Given these concerns, they prefer to control weeds throughout traditional methods, basically using mattocks with frequencies of 15 to 30 days after sowing or two to four times per cycle of crop production. Both pest and diseases are mainly controlled throughout chemical methods application. A preference to perform control among periods of higher rainfall or drought is not distinguished. A considerable percentage, which reaches 44% of the interviewed population among both municipalities, report they do not need to control pests and crop diseases. | Resumen La investigación se llevó a cabo en los municipios de Villaflores y Villa Corzo en el estado de Chiapas, a través de un enfoque etno-agronómico, se diseñaron y aplicaron entrevistas semiestructuradas a productores de chayote seleccionados por rutas aleatorias. Los resultados indican que el 57.89% de los productores de chayote de ambos municipios controlan las malezas en sus plantaciones, siendo mayor la proporción en Villaflores. Para controlar las malezas prefieren usar métodos culturales, fundamentalmente con la ayuda de coas o azadones y con frecuencias de 15 a 30 días después de la siembra o de dos a cuatro veces por ciclo de producción del cultivo. Las plagas y enfermedades se controlar mayoritariamente a través de métodos químicos, sobre todo en Villaflores durante la fase de fructificación. No se distingue una preferencia a realizar el control entre las épocas de mayores precipitaciones o durante la sequía. Un porcentaje considerable, que llega a alcanzar 44% del total de la población entrevistada entre ambos municipios, refieren que no necesitan controlar las plagas y enfermedades del cultivo.