Author : Neel Kamal
Publisher :
ISBN 13 :
Total Pages : 300 pages
Book Rating : 4.:/5 (975 download)
Book Synopsis Selection Progress and Cost Benefit Analysis of Iris Yellow Spot Resistance in Onions by : Neel Kamal
Download or read book Selection Progress and Cost Benefit Analysis of Iris Yellow Spot Resistance in Onions written by Neel Kamal and published by . This book was released on 2016 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Onion thrips (Thrips tabaci L.) and Iris yellow spot (IYS) disease caused by thrips-vectored Iris yellow spot virus (IYSV) are significant dangers to the viability of onion production worldwide. The absence of cultivars resistant/ tolerant to thrips and IYS, increased thrips resistance, and limited efficacy restrict growers' options for effective thrips control and reducing the spread of IYSV. The objective of this study were to measure selection progress for reduced/delayed IYS symptom expression after two selection cycles and to estimate the costs and benefits of IYS and/or thrips resistant germplasm. Plants from the original and selected populations along with a susceptible check, 'Rumba', were evaluated for thrips number and IYS disease severity and incidence from 2011 to 2014. First generation selections, NMSU 10-776, 10-807, and 10-813 tested in 2011 and 2012, and second generation selections, NMSU 12-239 and 12-243 tested in 2013 and 2014 had fewer thrips per plant, and lower disease severity and incidence than their original breeding lines on at least one occurrence. In some instances, an improvement in delayed symptom expression was observed with each selection cycle, such as with NMSU 12-243 (2nd), 10-813 (1st), and 07-53-1 (original). While for others, selection progress was not observed until the second selection cycle. Data on onion yield, bulb grades, and acreage were used from the Onion Variety Trails at the Malheur Experiment Station in Ontario, OR and the USDA annual vegetable summaries to estimate average losses under varied levels of thrips and IYS pressure. Average reduction in marketable bulb yield was estimated to be 4%, 10% and 20%, while gross returns were reduced by 4%, 10%, and 21% when 10, 25, and 50 percent of the bulbs in different market grades were reduced to the next lower market grade, respectively. A reduction of one insecticide spray application can increase net returns by $56 to $91 on a per acre basis depending upon the type of chemistry used. Overall, progress was observed in the selected material for reduced and delayed IYS symptom expression with the selection method used and further improvement might be achievable with additional cycles of selection.
