Authors:J. C. Reif, S. Hamrit, and A. E. Melchinger
It has been claimed that the system that delivers the products of plant breeding reduces the diversity of cultivated varieties, leading to increased genetic vulnerability. The objective of our study was to monitor the temporal trends in genetic diversity over the past five decades among maize cultivars with the largest acreage in Central Europe. Thirty individuals of five prominent open-pollinated varieties (OPVs) from Central Europe, 85 maize hybrids of economic importance, and their dent and flint parental components were examined with 55 SSRs. The genetic variation within and among varieties decreased significantly during the five decades. The five OPVs contain numerous unique alleles that were absent from the elite flint pool. Consequently, OPVs could represent useful sources for broadening the genetic base of elite maize breeding germplasm.
Authors:C. Bolduan, J. Montes, B. Dhillon, V. Mirdita, and A. Melchinger
Ear rots of maize caused by
spp. reduce grain yield and produce mycotoxins, which are harmful to humans and animals. To breed maize cultivars resistant to
spp., reliable large-scale phenotyping is essential. Our objectives were to (i) examine the precision of the ELISA method for determination of important mycotoxins, namely deoxynivalenol (DON) and fumonisins (FUM), (ii) evaluate the potential of near-infrared reflectance spectroscopy (NIRS) to estimate concentrations of DON and FUM in grain produced in inoculated maize plants, and (iii) compare the efficiency of ELISA, NIRS, and visual rating of disease severity for estimation of mycotoxin concentrations. Insignificant variation was observed between duplicate evaluations of DON and FUM by ELISA, showing the high repeatability of this method. DON and FUM determinations by ELISA were more closely correlated with mycotoxin concentrations predicted through NIRS than with visual rating of disease severity. For the prediction of DON, NIRS had very high magnitude of the coefficients of determination of calibration and cross validation (R
= 0.90–0.88). Thus, NIRS has a promising potential to predict DON concentration in grain samples of inoculated maize genotypes evaluated in resistance breeding programs.
Authors:C. F. H. Longin, H. F. Utz, A. E. Melchinger, and J.C. Reif
The optimum allocation of breeding resources is crucial for the efficiency of breeding programmes. The objectives were to (i) compare selection gain ΔGk for finite and infinite sample sizes, (ii) compare ΔGk and the probability of identifying superior hybrids (Pk), and (iii) determine the optimum allocation of the number of hybrids and test locations in hybrid maize breeding using doubled haploids. Infinite compared to finite sample sizes led to almost identical optimum allocation of test resources, but to an inflation of ΔGk. This inflation decreased as the budget and the number of finally selected hybrids increased. A reasonable Pk was reached for hybrids belonging to the q = 1% best of the population. The optimum allocations for Pk(q) and ΔGk
were similar, indicating that Pk(q) is promising for optimizing breeding programmes.