Heritability and Correlation Studies on Some Vegetative Traits in Nigerian Local White Onion, Allium cepa L.

Abstract

Heritability estimates for soluble solids, bulb firmness and bulb weight were earned out in two ways, namely, parent-offspring regression and half-sib family lntra-class correlation. Leaf characters were estimated only by half-.sib mtra-class correlations. For soluble solids the values were high (72 % and 58 % respectively), while the values for bulb weight and bulb firmness were low (20 % and 39 %, and 32 % and 33 % respectively) using the two methods. Some high additive genetic correlations were observed between bulb firmness and length of longest leaf [r^ = 0.830), bulb weight and leaf area of longest leaf {j,^ -0.704).In Nigeria storage of omon bulbs has been a ma|or constraint to farmers. Investigations show that up :o 75 % of storage losses have been recorded over a storage of 7 months (AGBAJI ct al. 1980). This problem can only be solved by producing varieties that store better m the local storage houses used by farmers, or those that are excellent for food processing industries as dehydrated onion. Because local white onion is thought to have a potential for improvement as variety suitable for dehydration, this heritable variation should be explored for breeding purposes. High dry matter content of the bulb has been found to enhance storability (FosKETTand PETERSON 1950) and is a major factor for varieties used m dehydration (SETHI et al. 1979). Materials and MethodsLocal white onion bulbs from collections were planted and the seed bulbs raised from them were grown to produce bulbs in 1979/80 dry season. The harvested bulbs were stored from April to September 1980, during which period the sprouted and rotten bulbs were frequently removed. In October 1980, 100 randomly selected bulbs were planted in an isolated field free from other onion pollen sources, for the production of maternal half-sib family seeds.Open pollination occurred, thus each plant was assumed to have equal opportunity to act as the pollen parent to each of the families. The limitations which might have prevented complete randomness were: variations in plant vigor and differences in flowering dates; if selfmg also occurred, all these could bias the heritability estimates. However, the uniformity with which the isolation plot matured suggests that these limitations, even if they have occurred, would be very negligible. The analysis for soluble solids was measured by the land type refractometer as outlined by MANN and HOYEE(1945). U.S. Copyright Clearance Center Code Sutemem: 01 79-954 1 /86/9703-0232$02.50/0

Genetic analysis of pungency and soluble solids in long-storage onions

“…or dissolved solids, they are a major factor in onion processing quality. McCollum (1968) and Kadams & Nwasike (1986) estimated the heritability of solids in several onion populations to be 0 .6 to 0 .8. To better understand the genetics of onion qualities this study evaluated pungency as estimated by pyruvate and soluble solids in an eight-inbred onion diallel for two years and in a 4-parent subset of this diallel for one or two more years .…”