Genetic and phenotypic correlation analyses on nine sweet corn advanced inbred lines using SAS PROC mixed model.

The mixed-model analysis of variance has been used in many recent studies in evolutionary quantitative genetics. In this two-way statistical model in SAS, the variance component corresponding to the random statement is the covariance associated with a level of the random factor across levels of the fix factor. Therefore, the SAS model has a natural application of estimating the genetic correlation among traits measured. Correlation studies were undertaken for ten yield related traits measured. Correlation studies were undertaken for ten yield related traits on a series of nine near-homozygous sweet corn inbred line obtained from various tropical source populations. The SAS program used estimated the genetic correlation coefficients among traits observed where blocks were considered as fix affects and inbred lines as random. The 'ASY COV' was added to the 'PRDC MIXED' statement in order to produce the variance-covariance matrix of variance components. The 'TYPE=UN' option requested in 'RANDOM' statement resulted in an unstructured covariance matrix for each inbred line being estimated, while the 'G' and 'GCORR' options produced genetic covariance-variance matrix and genetic correlation matrix between traits, respectively. In general, genetic correlation coefficients were greater than the corresponding phenotypic correlations. Husked fresh yield showed a positive significant genetic correlation with number of ears per hectare (0.99), plant height (0.97), dehusked ear yield (0.96), number of kernel rows per ear (0.91), ear diameter (0.74) and number of kernels per row (0.58). Total soluble solid concentration (-0.52) and days to silking (-0.51) were found to be negatively correlated with husked fresh yield. The interrelationship between these traits showed that they are under the influence of certain common genes, which can be exploited as selection criteria in breeding programs. Selection for one trait would also improve the other positively correlated traits. Husked fresh yield also revealed positive and significant phenotypic correlations with all traits mentioned for genetic relation. The interrelationship among these traits, therefore, revealed that husked fresh yield could be efficiently increased by obtaining maximum expression of number of ears per hectare, plant height, number of kernel rows per ear and ear diameter, and obtaining minimum expression of days to silking

Identification of Soybean Genotypes in Wide Rows for Use in NClI'row-row Culture

Thirty lines and six cultivars of soybeans (Glycine max (L.) Merr.) were evaluated in wide-row (76 em) and narrow-row (18 cm)spacingsat two locations in 1982 and one in 1983. The objective of the study was to determine if evaluation of lines in wide rows can be used to identify superior linesfor narrow-row culture. Yield in narrow rows was 27.0% higher than wide rows at both locations in 1982 and 20.8% higher in 1983. In general, the high yielding entries in wide rows were also the highest yielding ones in narrow rows, although they did not necessarily include all the highest yielding ones in narrow rows. One cultivar and two lines were, however, consistent in exhibiting a moderate to high response to narrowing of row spacing, over years and locations. No trait was identified as being associated with the response. In general, selection of lines superior in wide row nurseries will identify lines that will perform best in narrow-row culture

Genetic Control of Root Weight, Root Volume and Root to Shoot Weight Ratio in Peas

The genetic control of root weight, root volume and root to shoot weight ratio was studied in peas (Pisum sativum L.) at flowering. The four populations used were developed from crosses between lines and cultivars differing in size of the root systems. Plants of the F1, F2 , back cross and parental generations were evaluated in pots filled with soil: sand mixture, in a completely randomized design. A generation means analysis was used to determine the inheritance of the root characteristics. Root weight and volume exhibited moderate to high broad-sense heritability (0.41 - 0.81 for root weight, and 0.44 - 0.77 for root volume). Additive and dominance effects were important in the inheritance of root weight and volume in all populations, while epistatic effects were important only in two populations. The importance of the genetic parameters in the inheritance of root to shoot weight ratio was unclear. With the presence of large additive effects and high heritability, estimates for root weight and volume, selection for superior pure lines with large root systems should be effective

Performance and yield predictions in double cross hybrids of tropical grain maize

The use of double cross hybrids in maize was suggested to overcome the problem of seed production related to single cross resulting from low vigor and yield associated with the inbred parents. Double cross hybrids were known to perform quite well under a wide range of environmental conditions. As a part of an ongoing grain maize improvement program at Universiti Putra Malaysia, the best performing inbred lines were selected and crossed to produce single crosses. These single crosses were further used to produce some double cross hybrids. In this study, the performance of ten selected double cross hybrids was evaluated at two environments in the research areas of Universiti Putra Malaysia. The predicted performance of these double cross hybrids was also compared with the actual, using the method based on the mean values of non.parental single crosses. The best performing double cross hybrids, DC-26 and DC-34 were found to have high yields at both environments as well as in the combined analysis. DC-26 and DC-34 gave mean grain yields of 6125.0 and 5917.8 kg/ha respectively, at Field 2, 5648.9 and 5676.2 kg/ha respectively, at Share Farm, and 5887.0 and 5797.0 kg/ha respectively, in the combined analysis. From the correlation analysis, the actual and the predicted performances of the double cross hybrids were found to be in good agreement at each location and locations combined (r = 0.38, 0.46 and 0.27, respectively, at Field 2, Share Farm and at the two locations combined), implying that the method used for yield predictions in the crosses was appropriate

Effects of Location on Performance of Selected Tropical Maize Hybrids Developed in Malaysia

Eighteen selected locally-developed maize hybrids involving ten single, four double and four three-way crosses were evaluated with two open-pollinated check varieties (Metro and Suwan 1) at three locations in Peninsular Malaysia. The study was aimed to compare performance among the hybrids at the locations separately and when combined, to evaluate the genotype x location interaction revealed for yield and other important traits, and to estimate the heritability of the traits. Many hybrids were found to have out-yielded the check varieties. Significant effects of location for grain yield and most other traits indicated that the environmental and growth factors characterising the locations considerably affected the performance of the hybrids. Genotype x location interactions were not significant for the important traits, indicating that the ranking in performance of the genotypes was consistent among locations. Performance of the hybrids was best in Terengganu as compared to Selangor and Perlis. Higher heritability estimates for characters when measured in Terengganu further revealed the uniformity of environmental factors governing maize growth in that location. Based on the overall performance, three single crosses (SC-1, SC-2 and SC-8), one double cross (DC-11) and two three-way crosses (TWC-15 and TWC-17) were found to be highly potential for further trials towards new variety release

Inbreeding depression and heterosis in sweet corn varieties Manis Madu and Bakti-1

S1 and full-sib progeny families developed from selfing and crossing between Manis Madu and Bakti-1 sweet corn varieties were evaluated to estimate inbreeding depression and heterosis in the populations. Selfing has caused a significant decrease in the measurements of all characters taken in both selfed populations, except for days to tasseling which has shown an increase. Midparent heterosis estimates for the characters evaluated ranged from -2.83% to 22.34% for the Manis Madu X Bakti-1 cross progeny population (MMB1), and from -2.65% to 16.57% in the Bakti-1 X Manis Madu cross progeny population (B1MM). The two varieties revealed good potential to be used as parents for crosses between improved populations or inbred lines developed from them

PHYLOGENETIC RELATIONSHIPS AMONGST 10 Durio SPECIES BASED ON PCR-RFLP ANALYSIS OF TWO CHLOROPLAST GENES

Twenty seven species of Durio have been identified in Sabah and Sarawak, Malaysia, but their relationships have not been studied. This study was conducted to analyse phylogenetic relationships amongst 10 Durio species in Malaysia using PCR-RFLP on two chloroplast DNA genes, i.e. ndhC-trnV and rbcL. DNAs were extracted from young leaves of 11 accessions from 10 Durio species collected from the Tenom Agriculture Research Station, Sabah, and University Agriculture Park, Universiti Putra Malaysia. Two pairs of oligonucleotide primers, N1-N2 and rbcL1-rbcL2, were used to flank the target regions ndhC-trnV and rbcL. Eight restriction enzymes, HindIII, BsuRI, PstI, TaqI, MspI, SmaI, BshNI, and EcoR130I, were used to digest the amplicons. Based on the results of PCR-RFLP on ndhC-trnV gene, the 10 Durio species were grouped into five distinct clusters, and the accessions generally showed high variations. However, based on the results of PCR-RFLP on the rbcL gene, the species were grouped into three distinct clusters, and generally showed low variations. This means that ndhC-trnV gene is more reliable for phylogenetic analysis in lower taxonomic level of Durio species or for diversity analysis, while rbcL gene is reliable marker for phylogenetic analysis at higher taxonomic level. PCR-RFLP on the ndhC-trnV and rbcL genes could therefore be considered as useful markers to phylogenetic analysis amongst Durio species. These finding might be used for further molecular marker assisted in Durio breeding program

Heritability and Response to Recurrent Selection in Two Sweet Corn Varieties

One cycle of simple and full-sib reciprocal recurrent selection programme was conducted on two sweet corn varieties, Manis Madu and Bakti-1, at Universiti Pertanian Malaysia. The objectives of the study were to compare the response to the two selection procedures, and to estimate heritability of some important characters in the two populations. The presence of higher genetic variance in Bakti-1 S1 population (B1S) compared to that of Manis Madu (MMS) showed that B1S1possessed higher genetic variability than MMS. Broad-sense heritability estimates for the characters studied were moderate to high (42.6% to 65. 7%) in the selfed progeny populations, but were low to moderate (20.0 % to 49.2 %) in the crossed progeny populations. After one cycle of selection, simple recurrent selection was found to be more effective in increasing yield in both populations. Simple recurrent selection increased fresh ear yield in Bakti-1 and Manis Madu by 16. 7% and 10.2% respectively, while full-sib reciprocal recurrent selection increased it in Bakti-1 by 5.9 %, but decreased it in Manis Madu by 6.4 %