FAKTORI KOJI UTJEČU NA EFIKASNOST GENOMSKIH PREDVIĐANJA U TESTKRIŽANCIMA BIPARENTALNE POPULACIJE

Genomic prediction accuracy (r_MP) is affected by many factors, such as the trait heritability, training population size and structure, and the number of markers. This study’s objective was to investigate the factors associated with r_MP for the ear height and the plant height in two planting densities in testcrosses of maize (Zea mays L.) IBM population. Genetic correlations between the training and validation populations were calculated. The high heritability estimates and correlations between the traits were observed. The non-zero estimates of r_MP for all trait-density combinations implied an efficiency of genomic selection. The lower than expected values of genetic correlations were observed between the training and validation populations. However, a strong correlation was observed between a genetic correlation of training and the validation population and r_MP in all three sizes of training populations assessed (20-40%, 40-60%, and 60-80%), suggesting that the size of the training population can be kept low by an appropriate selection while maintaining a high r_MP. Further studies of relationships between the training and validation populations with larger effective population sizes are suggested, as reducing the size of training population while maintaining a high r_MP can facilitate a more effective allocation of resources in a maize breeding program.Mnogi faktori, kao što su heritabilnost svojstva, veličina i struktura radne populacije i broj markera, utječu na efikasnost genomskih predviđanja (r_MP). Cilj ovoga rada bio je ispitati faktore povezane s〖 r〗_MP za visinu klipa i visinu biljke u dvije gustoće sjetve kod test-križanaca IBM populacije kukuruza (Zea mays L.). Izračunane su genetske korelacije između radne i validacijske populacije. Dobivene su visoke procjene heritabilnosti i korelacije između svojstava. Procjene r_MP bile su različite od nule za sve kombinacije svojstvo -gustoća. što ukazuje na efikasnost genomske selekcije. Vrijednosti genetskih korelacija između radne i validacijske populacije bile su niže od očekivanih. Međutim, jaka korelacija dobivena je između genetske korelacije radne i validacijske populacije i r_MP za sve tri veličine radne populacije (20-40%, 40-60% i 60-80%), što ukazuje da se uz odgovarajuću selekciju veličina radne populacije može održati niskom zadržavajući visoku vrijednosti〖 r〗_MP-a . Potrebna su daljnja istraživanja odnosa između radne i validacijske populacije s većom efektivnom veličinom populacije jer smanjivanje veličine radne populacije, uz održavanje visoke vrijednosti〖 r〗_MP-a može omogućiti učinkovitiju alokaciju resursa u oplemenjivačkome programu kukuruza

HETEROSIS AND HETEROBELTIOSIS FOR GRAIN YIELD COMPONENTS IN SOYBEAN

Cilj ovog istraživanja bio je procijeniti heterozis i heterobeltiozis za četiri komponente uroda zrna soje te usporediti vrijednosti svojstava F1 hibrida sa roditeljima. Ispitivano je 29 genotipova: 11 roditeljskih i 18 F1 hibrida. Pozitivni heterozis i heterobeltiozis procijenjen je za broj mahuna po biljci (18,75%; 7,9%), broj zrna po biljci (16,14%; 3,98%) te za masu zrna po biljci (25,72%; 11,87%). Za žetveni indeks po biljci dobiven je niski pozitivni heterozis (6,62%) i negativni heterobeltiozis (-1,08%). Kombinacije križanja koje se odlikuju visokim prosječnim vrijednostima i pozitivnim procjenama heterozisa za većinu analiziranih svojstava (Ika x Vita, Podravka 95 x Ika, Ika x OS-1212-05) su populacije iz kojih se očekuje izbor novih superiornih linija. U cjelini, dobiveni rezultati ovog istraživanja doprinjet će učinkovitosti oplemenjivačkog postupka u povećanju genetskog potencijala rodnosti domaće germplazme soje.The objective of this research was to evaluate heterosis and heterobeltiosis for four grain yield components in soybean and to compare performances of the F1 hybrids with those of the parents. The research involved 29 genotypes: 11 parental and 18 F1 hybrids. Positive heterosis and heterobeltiosis were evaluated for the pod number per plant (18.75%; 7.9%), seed number per plant (16.14%; 3.98%) and for the seed weight per plant (25.72%; 11.8%). Low positive heterosis (6.62%) and negative heterobeltiosis (-1.08%) were determined for the trait harvest index per plant. The cross combinations characterized by high mean values and positive evaluations of heterosis for most analyzed traits (Ika x Vita, Podravka 95 x Ika, Ika x OS-1212-05) are populations from which selection of new superior lines are expected. Generally, the obtained results of this study will contribute to the efficiency of the breeding process to the increasing of yield genetic potential in the domestic soybean germplasm

Influence of Relative Humidity and Temperature on the Changes in Grain Moisture in Stored Soybean and Maize

These investigations aimed to determine influence of the changes in relative humidity and temperature in storage facilities on the moisture in grain of stored soybean and maize. Soybean (“Podravka 95” variety) and maize (“OSSK 644” hybrid) were stored during 34 days at the temperatures of 0oC and 20oC, and relative humidity of 55%, 73%, 80% and 98%. At the temperature of 0oC and relative humidity of 55% and 73%, moisture in soybean grain decreased, 2.4% and 1.9%, while at the relative humidity of 80% and 98% it increased, 0.2% and 0.6% aft er 34 days storage. At the temperature of 20°C and relative humidity of 55% and 73%, moisture in soybean grain decreased 4.0% and 0.7%, while at the relative humidity of 80% and 98% it increased 0.8% and 2.3%, as following. During 34 days storage at 0°C and relative humidity of 55%, moisture in maize grain decreased 0.2%, while at the relative humidity of 73%, 80% and 98% it increased 0.4%, 1% and 1.5%. At the temperature of 20°C and relative humidity of 55%, moisture in maize grain decreased 1.5% and at the relative humidity of 73%, 80% and 98% increased, 0.2%, 0.9% and 1.7%. Such investigations enable additional insights into the rate of changes in grain, and the influence on the grain viability in changed storage conditions

UTJECAJ GUSTOĆE SJETVE NA AGRONOMSKA SVOJSTVA I FOTOSINTETSKU UČINKOVITOST IBM POPULACIJE KUKURUZA

Photosynthesis is a vital process in plant physiology. Performance index is an indicator of plant vitality and is used as a main parameter in chlorophyll fluorescence measurements. Plant density is an important factor in maize production that can affect grain yield. Objective of this paper was to estimate the effect of plant density on agronomic traits and photosynthetic efficiency in the maize IBM population. The results showed a decrease in grain yield per plant basis (20 plants per plot) in higher plant density (normal density - 3.88 kg per plot, high density - 2.95 kg per plot) and an increase in grain yield per unit area (yield/ha) in higher plant density (normal density - 11.03t ha-1, high density - 13.64 t ha-1). Performance index was decreased in higher plant density (normal density - 5.31, high density - 4.95). Statistical analysis showed highly significant effect (p<0.001) of density on performance index and highly significant effects (p<0.001) of plant density and genotype on maize yield. Low positive correlation was observed between grain yield per plot and performance index (r = 0.36, p<0.001).Fotosinteza je vitalni dio biljne fiziologije. Indeks fotosintetske učinkovitosti (eng. performance index) indikator je vitalnosti biljke i koristi se kao glavni parametar u mjerenju fluorescencije klorofila. Gustoća sklopa važan je faktor proizvodnje kukuruza, koji može utjecati na prinos zrna. Cilj ovoga istraživanja bio je procijeniti utjecaj gustoće sklopa na agronomska svojstva i fotosintetsku učinkovitost kod IBM populacije kukuruza. Rezultati su pokazali smanjenje prinosa zrna na osnovijedne biljke (20 biljaka po parceli) u gušćem sklopu (manja gustoća sklopa - 3,88 kg po parceli, veća gustoća sklopa - 2,95 kg po parceli) i povećanje u prinosu zrna na osnovi prinosa po jedinici površine (prinos/ha) u gušćem sklopu (manja gustoća sklopa - 11,031 ha-1, veća gustoća sklopa 13,641 ha-1). Indeks fotosintetske učinkovitosti smanjio se s povećanjem gustoće sklopa (manja gustoća sklopa - 5,31, veća gustoća sklopa 4,95). Statističkom analizom utvrđen je značajan utjecaj (p<0,001) gustoće sklopa na indeks učinkovitosti fotosinteze i statistički značajni utjecaji (p<0,001) gustoće sklopa i genotipa na prinos zrna. Uočena je slaba pozitivna korelacija između prinosa zrna po parceli i indeksa učinkovitosti fotosinteze (r=0.36, p<0,001)

Use of chlorophyll a fluorescence in indirect selection for agronomic characteristics of maize

Kukuruz je jedna od najvažnijih žitarica na svijetu te je cilj oplemenjivačkih programa maksimizacija genetičke dobiti po jedinici vremena. Stoga je važno pronaći sekundarna svojstva koja su u korelaciji s prinosom i imaju visoku heritabilnost, što omogućuje indirektnu selekciju za svojstva od interesa. Pristup indirektnoj selekciji statističkim modeliranjem korištenjem senzorskih, fiziološki relevantnih podataka predstavlja novi izazov modernog oplemenjivanja bilja. Analiza fluorescencije klorofila jedna je od najkorištenijih tehnika za proučavanje utjecaja stresa na fotosintezu. Primjena fluorescencije klorofila značajno je poboljšana u zadnja dva desetljeća, a formirani su i mnogi drugi informativni parametri za određivanje učinkovitosti PSII i raspodjele svjetlosne energije alternativnim mehanizmima. U ovome radu utvrđivala se genetička varijabilnost u svojstvima fluorescencije klorofila a, genetičke korelacije između svojstava fluorescencije klorofila a i agronomskih svojstava te struktura varijance kod 16 hibrida kukuruza. Dodatni ciljevi bili su izraditi regresijski model sa svojstvima fluorescencije klorofila a kao prediktorima i agronomskim svojstvima kao zavisnim varijablama, istražiti strukturu varijance i heritabilnosti predviđanja te procijeniti učinkovitost indirektne selekcije u odnosu na izravnu selekciju. Analiza varijance pokazala je statistički značajne učinke genotipa, godine, ponavljanja i bloka za svojstvo Fv/Fm. Utvrđene su značajne razlike u Fv/Fm vrijednostima između ispitivanih hibrida kukuruza. Model s 10 latentnih varijabli ima veću prediktivnu sposobnost za predviđanje prinosa od ostalih modela. Korištenje tranzijenata fluorescencije može biti korisno u predviđanju vlažnosti zrna u berbi. Učinkovitost indirektne selekcije za prinos zrna bila je niža nego kod izravne selekcije, dok je učinkovitost indirektne selekcije za vlagu zrna bila relativno visoka. Rezultati ovoga istraživanja naglašavaju važnost i upotrebljivost parametara fluorescencije klorofila a u oplemenjivačkim programima kukuruza.Maize is one of the most important cereals in the world. The goal of breeding programs is to maximize genetic gain per unit of time, therefore in breeding programs it is important to find secondary traits that are correlated with yield and have high heritability, which enables indirect selection for traits of interest. The approach to indirect selection by statistical modeling using sensors and physiological data represents a new challenge of modern plant breedingl. The study of photosynthetic mechanisms is a very important line of research in order to achieve a better understanding of the impact of unfavorable external conditions on maize production. Chlorophyll fluorescence analysis is one of the most used techniques for studying the effects of stress on photosynthesis. The application of chlorophyll fluorescence has significantly improved in the last two decades. Many different informative parameters have been developed to determine the efficiency of PSII and the distribution of light energy by alternative mechanisms. In this study, genetic variability in chlorophyll a fluorescence parameters, genetic correlations between chlorophyll a fluorescence parameters and agronomic properties, and variance structure in 16 corn hybrids were determined. Additional goals were to develop a regression model with chlorophyll a fluorescence parameters as predictors and agronomic traits as dependent variables, to investigate the structure of variance and heritability of predictions, and to evaluate the effectiveness of indirect selection in relation to direct selection. Analysis of variance showed statistically significant effects of genotype, year, replication and block for the trait Fv/Fm. Significant differences in Fv/Fm values were found between the evaluated maize hybrids. The model with 10 latent variables has a higher predictive ability for yield prediction compared to other models. The use of fluorescence transients can be useful in predicting grain moisture at harvest. The efficiency of indirect selection for grain yield was lower than that of direct selection, while the efficiency of indirect selection for grain moisture was relatively high. The results of this research emphasize the importance and applicability of chlorophyll a fluorescence parameters in maize breeding programs

Factors affecting the accuracy of genomic predictions in testcrosses of maize biparental population

Genomic prediction accuracy (r_MP) is affected by many factors, such as the trait heritability, training population size and structure, and the number of markers. This study’s objective was to investigate the factors associated with r_MP for the ear height and the plant height in two planting densities in testcrosses of maize (Zea mays L.) IBM population. Genetic correlations between the training and validation populations were calculated. The high heritability estimates and correlations between the traits were observed. The non-zero estimates of r_MP for all trait-density combinations implied an efficiency of genomic selection. The lower than expected values of genetic correlations were observed between the training and validation populations. However, a strong correlation was observed between a genetic correlation of training and the validation population and r_MP in all three sizes of training populations assessed (20-40%, 40-60%, and 60-80%), suggesting that the size of the training population can be kept low by an appropriate selection while maintaining a high r_MP. Further studies of relationships between the training and validation populations with larger effective population sizes are suggested, as reducing the size of training population while maintaining a high r_MP can facilitate a more effective allocation of resources in a maize breeding program.Mnogi faktori, kao što su heritabilnost svojstva, veličina i struktura radne populacije i broj markera, utječu na efikasnost genomskih predviđanja (r_MP). Cilj ovoga rada bio je ispitati faktore povezane s〖 r〗_MP za visinu klipa i visinu biljke u dvije gustoće sjetve kod test-križanaca IBM populacije kukuruza (Zea mays L.). Izračunane su genetske korelacije između radne i validacijske populacije. Dobivene su visoke procjene heritabilnosti i korelacije između svojstava. Procjene r_MP bile su različite od nule za sve kombinacije svojstvo -gustoća. što ukazuje na efikasnost genomske selekcije. Vrijednosti genetskih korelacija između radne i validacijske populacije bile su niže od očekivanih. Međutim, jaka korelacija dobivena je između genetske korelacije radne i validacijske populacije i r_MP za sve tri veličine radne populacije (20-40%, 40-60% i 60-80%), što ukazuje da se uz odgovarajuću selekciju veličina radne populacije može održati niskom zadržavajući visoku vrijednosti〖 r〗_MP-a . Potrebna su daljnja istraživanja odnosa između radne i validacijske populacije s većom efektivnom veličinom populacije jer smanjivanje veličine radne populacije, uz održavanje visoke vrijednosti〖 r〗_MP-a može omogućiti učinkovitiju alokaciju resursa u oplemenjivačkome programu kukuruza