Impact of cytoplasmic male sterility and xenia on grain yield and agronomic traits of maize

Citoplazmatična muška sterilnost (CMS) odavno se koristi u proizvodnji hibridnog semena kukuruza, jer povećava kvalitet, a pritom smanjuje troškove proizvodnje. Ksenija predstavlja efekat stranog oprašivača na zrno majčinskog genotipa u godini oprašivanja. Kombinovani uticaj CMS i ksenija nazvan je Plushibrid efekat, a ideja je da se u smeši gaji 80% sterilnog hibrida kao majke i 20% drugog fertilnog hibrida, kao oca. Mnogi autori su dobili značajno povećanje prinosa u ovakvom sistemu proizvodnje, bez pogoršanja kvaliteta zrna. Cilj istraživanja bio je da se u našim uslovima i na domaćim hibridima ispita pojedinačni i kombinovani uticaj citoplazmatične muške sterilnosti i ksenija na najvažnije osobine kukuruza i mogućnost uvođenja ovakvog sistema gajenja u komercijalnu proizvodnju u Srbiji. Ogled je bio postavljen po potpuno slučajnom blok (RCB) split-split plot eksperimentalnom dizajnu u tri ponavljanja u Zemun Polju od 2009. do 2011. godine. Kao majke su se koristili sterilne (CMS-S tip) i fertilne verzije hibrida ZP 1 i ZP 2, dok su očevi bili hibridi ZP 1ft, ZP 2ft, ZP 3ft, ZP 4ft i ZP 5ft. Ispitivan je pojedinačni, kao i kombinovani uticaj CMS i ksenija na najbitnije osobine kukuruza. Takođe, pomoću SSR markera utvrđena je genetička distanca između korišćenih genotipova, da bi se našla veza između distance i efekta ksenija u Plus-hibrid kombinaciji. Samo kod jednog CMS hibrida, ZP 2st, je došlo do neznačajnog povećanja prinosa zrna (0,45 t/ha), kod kog je došlo i do značajnog povećanja težine zrna i broja zrna po jedinici površine. Slab odgovor genotipova na sterilnost objašnjava se time što je korišćen CMS-S tip, kod koga pozitivan efekat sterilnosti ne dolazi do izražaja kao kod ostala dva tipa. CMS je uticala na značajno povećanje sadržaja ulja u zrnu kod ZP 2 (0,21%). Infekcija zrna sa Fusarium verticillioides bila je veća kod oba sterilna hibrida, dok je sadržaj mikotoksina specifičnog za ovu vrstu gljive,..Because it increases quality and reduces costs at the same time, cytoplasmic male sterility (CMS) has been used in maize hybrid seed production since long ago. Xenia is the effect of foreign pollinator on the kernel of maternal genotype in the year of crossing. The combined effect of CMS and xenia is referred to as a Plushybrid effect and the idea is to grow in mixture 80% of one sterile hybrid as mother and 20% of the other fertile hybrid as father. Many authors got significant increase in grain yield in this production system, without grain quality deterioration. The aim of the research was to examine individual and combined effect of cytoplasmic male sterility and xenia on the most important maize traits of domestic hybrids, in our environment, as well as the possibility of introduction of this kind of growing system in the commercial production in Serbia. The three-replicate trial was carried out according to randomized complete block (RCB) split-split plot design in Zemun Polje during 2009, 2010 i 2011. Sterile (CMS-S type) and fertile versions of ZP 1 and ZP 2 hybrids were used as mothers, while ZP 1ft, ZP 2ft, ZP 3ft, ZP 4ft and ZP 5ft hybrids were fathers. Individual and combined effects of CMS and xenia on the most important maize traits were examined. Also, genetic distance between used genotypes was determined using SSR markers, to find the relationship between distance and xenia effect in a Plushybrid combination. Only one CMS hybrid, ZP 2st, had insignificant increase in grain yield (0,45 t/ha), and at the same time significant increase in kernel weight and kernel number per unit area. Weak response of the genotypes to sterility is explained with the use of CMS-S type, in which positive effect of sterility doesn’t come to the fore as in the other two types. CMS had significant impact on kernel oil content increase in ZP 2 (0,21%). Kernel infection with Fusarium verticillioides was higher for both sterile hybrids, while kernel content of mycotoxin fumonisin B1, specific for this fungi species, in ZP 1st was significantly lower, and in ZP 2st insignificantly higher then in fertile analogue..