This study aimed to investigate the impact of cold stress and priming on photosynthesis in the early development of maize and soybean, crops with diverse photosynthetic pathways. The main objectives ...were to determine the effect of cold stress on chlorophyll
fluorescence parameters and spectral reflectance indices, to determine the effect of cold stress priming and possible stress memory and to determine the relationship between different parameters used in determining the stress response. Fourteen maize inbred lines and twelve soybean cultivars were subjected to control, cold stress, and priming followed by cold stress in a walk-in growth chamber. Measurements were conducted using a portable fluorometer and a handheld reflectance instrument. Cold stress induced an overall downregulation of PSII-related specific energy fluxes and efficiencies, the inactivation of RCs resulting in higher energy dissipation, and electron transport chain impairment in both crops. Spectral reflectance indices suggested cold stress resulted in pigment differences between crops. The effect of priming was more pronounced in maize than in soybean with mostly a cumulatively negative effect. However, priming stabilized the electron trapping efficiency and upregulated the electron transfer system in maize, indicating an adaptive response. Overall, this comprehensive analysis provides insights into the complex physiological responses of maize and soybean to cold stress, emphasizing the need for further genotype-specific cold stress response and priming effect research.
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.
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).
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.
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.
The effectiveness of biological nitrogen fixation in soybean linked to genotype and environment was tested using the number and dry weight of nodules per plant, above-ground plant mass, nitrogen ...content in the above-ground part of plant and grain yield. A field study conducted in eastern Croatia from 2004 to 2007 year and involved 8 cultivars in two variants of seed inoculation byBradyrhizobium japonicum(uninoculated and inoculated). Significant increasing of grain yield affected by inoculation was determined. Effectiveness of biological nitrogen fixation was significantly varied depends on genetic factor, environmental variables and their interaction. Genetic improvement of soybean for biological nitrogen fixation has economical and ecological benefits for soybean production.
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 0 degree C and 20 degree C, and relative humidity of 55%, 73%, 80% and 98%. At the temperature of 0 degree C 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% after 34 days storage. At the temperature of 20 degree 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 degree 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 degree 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.
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.
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).
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.
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