Growth Dynamics and Water Potential Components of Three Summer Squash (&lt;i&gt;Cucurbita pepo&lt;/i&gt; L.) Cultivars

Alejo Rodríguez-Burgos,Dolores Muy-Rangel,Adriana Sañudo-Barajas,Tomás Osuna-Enciso,Manuel Báez-Sañudo,Misael Odín Vega-García,José De Jesús Zazueta-Morales,Rosalba Contreras-Martínez,Armando Carrillo-López

doi:10.15835/nbha4329827

Abstract

Summer squash fruit is a horticultural crop that possesses a very short postharvest life due to its high rates of metabolism and transpirationalong with a low cuticle resistance exhibited mainly when the fruit is harvested at horticultural maturity. This research was realized following thefruit growth of the summer squash cultivars: ‘Enterprise’, ‘Pascola’ and ‘Hurakan F1’, whose seeds were germinated in polystyrene trays and theirseedlings were subsequently transferred to pots for optimum growth under greenhouse conditions. Fruits were sampled at 3, 5, 7 and 9 days afteranthesis (DAA). Physical (weight, diameter, and length of fruit), chemical (pH, titratable acidity and total soluble solids), hydric status (water,osmotic and pressure potentials), and histological analysis were done. The highest number of fruits having marketing quality were shown in both‘Pascola’ and ‘Hurakan F1’ cultivars at 7 DAA, whereas, in ‘Enterprise’ was shown at 9 DAA. Marketing quality fruits from the three cultivarsshowed similarities on pH (about 6.6), titratable acidity (TA) decreases in ‘Enterprise’ and ‘Hurakan F1’, whereas total soluble solids (TSS)decreases in ‘Pascola’ and ‘Hurakan F1’ (pJ 0.5). From 3 to 9 DAA, in all cultivars, the water potential was close to -1.0 MPa, the osmoticpotential showed an increasing pattern ranging between -1.59 and -1.15 MPa, and the pressure potential remained in the positive range. Tissuewater stability was histologically related to a well-defined parenchyma tissue showing thin-walled, polygonal, intact and turgid cells during fruitgrowth.

Highlights

Mexico is among the ten major squash (Cucurbita pepo L.)producing countries all over the world, with about 400,000 tons produced in 2013
It is well known about the growth behaviour exhibited for squash fruit according to Sedano et al (2005) who reported that squash fruit of ‘Tala’ variety (Cucurbita pepo L.) showed a sigmoid-like continuous growth behaviour, a high concentration of solids and good organ integrity in the stage of maximum development
The whole period to achieve horticultural maturity was composed by a germination stage of 8 days, a vegetative growth stage of 27-35 days and a fruit growth stage of 7-9 days

Summary

Introduction

Mexico is among the ten major squash (Cucurbita pepo L.)producing countries all over the world, with about 400,000 tons produced in 2013. Water status of fruit during pre-harvest, along with chemical changes has been scarcely studied in summer squashes. This work aimed in monitoring physical, chemical and water status changes (water-, osmotic- and pressure potential) of fruits for three different squash cultivars during its growth till horticultural maturity.

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Results

Conclusion