YIELD AND GROWTH OF TWO VARIETIES OF ONION IN FIVE PLANTING DATES IN THE REGION OF DELICIAS, CHIH.

Abstract

Onion (Allium cepa) is the second most important vegetable crop grown in the area of Delicias, Chih., just behind chile jalapeño (Capsicum annum). In this area about 2000 ha are under cultivation, annually, 76% of which is grown in the winter season while 24% is grown in the spring season.
When onion is grown in winter, planting dates range is from September 23 to November 30. This range affects both yield quality and quantity; therefore, in the winter of 1980 the effects of planting dates on yield, growth and development of two varieties of this crop were studied. 

Results indicated that the later planting dates shortened the plant vegetative cycle and made the plants shorter with lower foliage and bulb dry matter production with a consequent significant yield reduc­tion. lt is assumed that temperature was the main environmental factor involved in these responses.
Growth dynamic behavior followed the sigmoid curve, while the static one (at the end of the cycle) followed a second grade curve. The best planting date, based on yield quantity and quality, was October 9 and the best genotype was Texas Early Grano.