Effect of Seed Vigor Upon Field Performance and Yield of Grain Sorghum (Sorghum Bicolor (L.) Moench)

Effect of Seed Vigor Upon Field Performance and Yield of Grain Sorghum (Sorghum Bicolor (L.) Moench)
Author: Cilas P. Camargo
Publisher:
Total Pages: 150
Release: 1971
Genre: Sorghum
ISBN:

Hybrid grain sorghum seeds were aged artifically for 0, 3, 5, 7, and 11 days at 42oC and 100% RH, wich produced high, medium, low and lowest vigor level. Among the various laboratory tests performed, standard germination and field mergence, were the least sensitive in discerning the physiological condition of the seed lots. The speed of germination more accurately differentiated the degree of deterioration of the seed lots and was closety correlated to yield. Adverse effect of planting low vigor seeds was found to be related to plant height, panicle exsertion, anthesis, tillering capacity, length of the panicle, and yield. Less vigours seeds produced plants which were not able to "catch up" to the vigorous ones. These slow growing plants were significantly inferior in panicle exsertion to those produced from more vigorous seeds. Seeds aged for 7 and 11 days had their process of exsertion delayed for about 2 and 3 days, respectively. Anthesis, conseguently, was also significantly retarded. Tillering capacity of plants produced from low vigor seeds was significantly reduced, as well as grain yield. Primary head yield was also significantly reduced about 14% for the more deteriorated seeds, and 12% for the mixed treatment, as compared to the control. Yield reductions of 9, 4, and 3% were also detected in seeds aged for 7, 5, and 3 days, respectively, as compared to the check. Seed moisture content generally increases as the vigor level decreased, indicating that the process of maturation was delayed as a (...).

Agronomic, Genetic and Genomic Approaches for Predicting Heterosis in Sorghum [Sorghum Bicolor (L.) Moench]

Agronomic, Genetic and Genomic Approaches for Predicting Heterosis in Sorghum [Sorghum Bicolor (L.) Moench]
Author: Frank Maulana
Publisher:
Total Pages:
Release: 2016
Genre:
ISBN:

The approach used to identify inbred lines that can produce superior hybrids is costly and time-consuming. It requires creation of all possible crosses and evaluation of the crosses to estimate combining abilities for the desired traits. Predicting heterosis or hybrid performance in any way possible may help to reduce the number of crosses to be made and evaluated. In this study, four sets of experiments were conducted to determine whether heterosis can be predicted based on inbred line performance, genetic distance between parents and genomic prediction model. The first experiment was aimed at assessing the levels of genetic diversity, population structure and linkage disequilibrium (LD) in 279 public sorghum inbred lines, based on 66,265 SNPs generated using the genotyping-by-sequencing (GBS) platform. The inbred lines were developed at different times over the last two decades and harbor robust diversity in pedigree and agronomic characteristics. Some of the inbreds are resistant to Acetolactate synthase (ALS) and Acetyl co-enzyme-A carboxylase (ACC) inhibitor herbicides. The mean polymorphic information content (PIC) and gene diversity across the entire inbreds were 0.35 and 0.46, respectively with non-herbicide resistant inbreds harboring more diversity than the herbicide resistant ones. The population structure analysis clustered the inbred lines into three major subgroups according to pedigree and fertility-reaction with the maintainer lines (B-lines) distinctly forming a separate cluster. Analysis of molecular variance (AMOVA) revealed more variation within subgroups than among subgroups. Substantial linkage disequilibrium (LD) was detected between the markers in the population with marked variation between chromosomes. This information may facilitate the use of the inbreds in sorghum breeding programs and provide perspectives for optimizing marker density for gene mapping and marker-assisted breeding. The second experiment, based on 102 F1 hybrids developed by intercrossing closely and distantly related inbreds, was conducted to investigate the relationship of genetic distance between parents with hybrid vigor or heterosis. The F1 hybrids alongside their parents were evaluated at two environments in a randomized complete block design with three replications. The results show that correlations of genetic distance between parents with hybrid performance and heterosis were variable and dependent on the trait. Though most were statistically non-significant and not strong to be used as predictor for heterosis, the results tend to show that certain level of genetic distance between parents is needed to capture maximum heterosis and hybrid performance. The objective of the third research study was to determine whether traits measured on parents can be used to predict hybrid performance in sorghum and to assess the combining ability of selected inbreds. Forty-six parental inbred lines and 75 F1 hybrids generated from intercrossing the inbreds were evaluated in four environments in a randomized complete block design with three replications. The average performance of the parents (mid-parent) was significantly correlated with hybrid performance for thousand kernel weight, days to flowering and plant height. Significant general (GCA) and specific (SCA) combining abilities were observed for most traits, with highly significant GCA effects observed for most traits as compared to SCA indicating that additive genetic effects are more important in affecting the inheritance of the traits measured. Results show that studying parental inbred line performance could generate important information for predicting hybrid performance in sorghum. The fourth experiment was aimed at assessing the efficacy of genomic prediction of hybrid performance in sorghum. Genomic prediction was performed with five-fold cross-validation procedure on 204 F1 hybrids developed using 102 inbred lines. A total of 66,265 SNP markers generated using genotyping-by-sequencing were used in this study. Results showed that increasing training population size increased prediction accuracies for all traits with the effect being different for different traits. Also, considering additive effects alone versus additive and dominance effects in the model showed similar trend of prediction accuracy but the full model (considering both additive and dominance effects of the markers) provided better prediction at least for some of the traits. The results suggest that genomic prediction could become an effective tool for predicting the performance of untested sorghum hybrids thus adding efficiency to hybrid selection.

Grain Sorghum Field Emergence and Seed Vigor Tests

Grain Sorghum Field Emergence and Seed Vigor Tests
Author: C.E. Detoni
Publisher:
Total Pages: 129
Release: 1997
Genre:
ISBN:

Poor emergence of sorghum [(Sorghum bicolor (L) Moench] affects the stand and potential yields. The major objective of this research was to find correlations among field emergence data and laboratory seed vigor tests. Thirty-two and 30 hybrids of sorghum were planted at three Virginia locations in 1995 and 1996, respectively. Field emergence was subsequently compared with results from laboratory tests that included: 1) standard germination; 2) osmotic-stress using polyethylene glycol 8000 (mw); 3) heat-shock using 2 hr at 50o.C stress; 4) electrical conductivity of steep water of germinating seeds; and 5) seed mass. Field emergence of grain sorghum differed among hybrids years and locations. Mean emergence across years and locations was 67.5%, whereas mean germination in the laboratory was 87.8%. There were interaction between hybrid and loction and between hybrid and year. Germination under optimal conditions (standard germination test) and with osmotic or heat-shock stress differed among hybrids. Regression analyses showed a weak correlation between laboratory germination (with or without stress) and field emergence in both years. The fresh weight of seedlings whether from standard germination or stress tests also differed among hybrids in both years, and the associations with field emergence were weakly correlated in 1996. Hybrids showed significant differences in radicle length when grown under laboratory stress in both years following standard germination. There was weak correlation with field emergence and radicle length following heat-shock treatment in 1996. The measurement of electrical conductivity in the seed steep water showed significant differences among hybrids. A weak correlation with field emergence was seen in 1996. Conductivity values per gram of seed and per cm2 of seed area revealed differences among hybrids. The correlation of these parameters with field emergence was higher than conductivity per seed. Seed mass varied among hybrids in both years, but was no correlation between seed mass and emergence. Of the laboratory parameters examined, germination proved to be the most consistent predictor of variations in field emergence of sorghum hybrids.