This investigation was conducted at the Experimental Farm, Fac. Tech. and Develop. (Gazala region – Zagazig), Zagazig Univ., Sharkia Governorate under open field during the two fall – winter seasons of 2015/2016 and 2016/2017, to study the effect of three cultivars of squash ( Eskandarany, Revera and Azyad) and foliar spray treatments with, yeast extract at the rate of 3 and 6gl-1 ,as well as potassium silicate at the rate of 2 and 4gl-1 plus control (tap water)and their interactions on flowering expression, i.e., number of male and female flowers plant-1, sex ratio and femalness percentage, yield and its components (number of fruits plant-1 , fruit fresh weight, and dry matter percentage, total fruit yield plot-1 and relative yield), as well as fruit quality, i.e., fruit physical characters (both of fruit length and diameter) and fruit chemical composition (nitrogen, phosphorus and potassium content, protein and total carbohydrates percentage). Results showed the superiority of the two tested cultivars Azyad and Revera at all studied characteristics compared with Eskandarany cv. Spraying with yeast extract or potassium silicate significantly increased most parameters of flowering, fruit yield and quality attributes of squash than control treatment . Moreover, spraying plants with potassium silicate at rate of 4gl-1 or yeast extract at 6gl-1 significantly surpassed compared with the other foliar treatments and control in this respect. The best results of the interaction treatments for flowering, yield and fruit parameters were recorded by the two cultivars Azyad or Revera combined with the foliar spray by 4gl-1 of potassium silicate or 6gl-1 of yeast extract which recorded increased in most of all the mentioned studied parameters.
Hence, each of these treatments could be recommended for enhancement flowering, yield and fruit quality of squash plants with low cost production when planted in open field at fall – winter season under the same conditions of this experiment.