No abstract

The respiratory metabolism of fruits is affected by multiple internal (product) and external (environmental) factors that often interact with each other. Among the external factors that have the greatest influence on respiration are temperature, air composition, moisture content, and illumination. This paper aims to elucidate the influence of environmental factors on the respiration rate of peach fruits based on transfer models obtained by dynamic regression modelling (ARIMAX). The fitted ARIMA models met the criteria of parsimony and white noise in residuals. The estimated coefficients of each model were statistically significant under the Durbin-Watson (DW), Akaike (AIC) and Schwarz (SBC) criteria. Transfer functions revealed 0.15% and 1.9% increase, and 0.001% decrease in the respiration rate of the peach fruit for each unit of change in temperature, relative humidity, and the illumination of the storage environment, respectively. The respiration rate response took place 1-8 minutes after the change in environmental variables had occurred. It was concluded that the dynamic regression modelling is reliable for predicting the physiological response of fruits the effect of external factors imposed continuously during postharvest handling. Website: http://revistas.unitru.edu.pe/index.php/scientiaagrop Facultad de Ciencias Agropecuarias Universidad Nacional de Trujillo Scientia Agropecuaria 11(1): 23 -29 (2020) SCIENTIA AGROPECUARIA How to cite this article: Pérez-López, A.; Ramírez-Guzmán, M.E.; Espinosa-Solares, T.; Aguirre-Mandujano, E.; Villaseñor-Perea, C.A. 2020. Postharvest respiration of fruits and environmental factors interaction: An approach by dynamic regression models. Scientia Agropecuaria 11(1): 23-29. ORCID A. Pérez-López https://orcid.org/0000-0002-9844-697X M. Ramírez-Guzmán https://orcid.org/0000-0002-8840-3706 T. Espinosa-Solares https://orcid.org/0000-0002-7581-0249 E. Aguirre-Mandujano https://orcid.org/0000-0002-4403-358X C. Villaseñor-Perea https://orcid.org/0000-0002-7404-022X

Abstract. Mechanization of postharvest handling and conditioning inflicts damage on the physical, physiological, and sanitary qualities of corn (Zea mays) seeds, resulting in significant economic loss. The mechanical damage is related to the compression strength and strain, and therefore to the moisture content (MC) and endosperm type. This study was conducted from 2012 to 2014 at the Montecillo and Chapingo agricultural institutes in Mexico, where physical properties such as volumetric weight; apparent density; rupture compression strength, strain, and energy; and endosperm type were evaluated for five corn seed cultivars (floury, semi-floury, floury-flint, semi-flint, and flint) at seven MC levels (8%, 12%, 16%, 20%, 24%, 28%, and 32% w.b.). The aim of this study was to develop moisture-strength, moisture-strain, and moisture-energy regression models for postharvest handling of corn to prevent quality loss due to mechanization. For three model groups, the relationship (1) between MC and rupture strain was linear and directly proportional for the five studied cultivars; (2) between MC and rupture strength was linear and directly proportional for the floury cultivar, inverse for the semi-flint and flint cultivars, and quadratic for the semi-floury and floury-flint cultivars; and (3) between MC and rupture energy was linear and directly proportional for the floury cultivar and quadratic for the semi-floury, floury-flint, semi-flint, and flint cultivars. The models obtained in this study might be used as a reference for better handling of corn seeds, as none of the five studied varieties had a uniformly superior rupture strength, strain, or energy at the studied MC levels. Floury endosperm types might be handled at high MC and flint endosperm types might be handled at low MC to avoid mechanical damage produced by static loads; both types of endosperm support greater energy loads, e.g., impact, at higher MC. Keywords: Compression, Corn quality, Flint endosperm, Floury endosperm, Moisture, Zea mays.

No abstract

La ruptura en semillas reduce la germinación, aun si el daño no ocurre sobre tejido metabólico, y ocasiona un incremento de ataque de microorganismos. Comprender la mecánica de la falla de tejidos permitirá desarrollar condiciones de manejo más apropiadas para reducir los daños mecánicos o sus efectos, por lo que el objetivo de este estudio fue conocer la naturaleza de la falla de tejidos de la semilla de maíz (Zea mays L.) sometida a compresión axial, según el tipo de endospermo y contenido de humedad. Se evaluó la calidad fisiológica y el daño celular de semillas de maíz de tres variedades con endospermo harinoso (Cacahuacintle), semi-dentado (HS-2) y cristalino (Palomero), con contenidos de humedad de 12 y 20 % y comprimidas a velocidad de 1 mm min-1 entre platos pulidos hasta justo el momento en que se presentó la ruptura. En la zona de ruptura, el endospermo mostró una proporción de área de 92.20 % con ruptura de pared celular, superior al área de 7.8 % sin ruptura de pared celular; la aleurona también presentó una proporción de células con ruptura de pared celular de 87.8 %, superior a la de células sin ruptura de pared celular (12.3 %). No hubo fracturas sobre tejido embrionario ni escutelo; no obstante, la germinación en semillas sometidas a ruptura fue inferior (55.0 %) a la del testigo (85.2 %). La proporción de ruptura celular entre las dos humedades estudiadas difirió de manera significativa. No hubo diferencias significativas en la proporción de ruptura celular entre variedades. La germinación estándar de semillas de Cacahuacintle y HS2-2 comprimidas a ruptura fue superior con humedad de 12 % con respecto a aquellas comprimidas con humedad de 20 %.