Nitrogen mobilization in the grain filling period of spring barley

Abstract

An understanding of the partition between pre-anthesis and post-anthesis N uptake and their contribution to total grain N and protein content in spring two-rowed barley (Hordeum vulgare ssp. distichum L.) are important to achieve additional breeding progress for both fodder and malting barley. N translocation from the vegetative tissues at anthesis to the kernel, N translocation efficiency, and N harvest index (NHI) were studied in field experiments during four years (1995-1998). Plants were harvested at anthesis and maturity and divided into leaf+culm, chaff and grain. Significant cultivar differences in N translocation, N translocation efficiency and NHI were determined. Across cultivars, the highest N translocation was in a favorable year (93kg ha-1) and the lowest in a year with poor growing conditions (40kg ha-1). Cultivar differences in N translocation were related to dry matter and pre-anthesis N accumulation (R2>0.70). N translocation efficiency varied more among the cultivars (0.27-0.66) than years (0.47-0.52). Post-anthesis N uptake was in significant negative (P lt 0.01) correlation with N translocation. NHI ranged among the cultivars, i.e. the years from 0.49 to 0.73, i.e. 0.57 to 0.74, respectively. The cultivars Arapiles, Schooner, Cantala, Kaskade and Rek stored in the grain more than 70% and Hiproly less then 50% of aboveground N at maturity. Translocated N participated with 85%, 56%, 42%, and 61% in grain N in 1995, 1996, 1997, and 1998, respectively. The ratio of translocated N to grain N could be an indicator of growing conditions - a higher ratio indicates good growing conditions over the entire growth period, a lower ratio indicates poor conditions during pre-anthesis, and a medium ratio indicates some temperature and water deviations from the long-term average. Straw N concentration was in significant positive (P lt 0.01) correlation with N translocation and translocation efficiency. Moreover, straw N concentration adequately represents N efficiency utilization for synthesis of grain protein, and because it saves time and money compared to N harvest index determination, it can be used for the testing of breeding materials in the development of new barley cultivars.

Azot (N) u proteinima zrna ječma (Hordeum vulgare L.) može voditi poreklo od azota usvojenog do cvetanja i translociranog u zrno tokom njegovog nalivanja i azota usvojenog tokom perioda rasta i razvoja zrna. Poznavanje udela ova dva izvora N je važno u programu stvaranja ekonomičnih sorti pivskog i stočnog ječma dobrih tehnoloških osobina. U ovom radu su prikazani četvorogodišnji rezultati proučavanja translokacija N i žetvenog indeksa azota kod 20 sorti jarog ječma. Sadržaj N u pojedinim biljnim organima određivan je u fazi cvetanja i zrenja, a na osnovu toga izračunate su vrednosti translokacije azota (TN), efikasnosti translokacije azota (ETN) i žetveni indeks azota (NHI). TN je zavisila od uslova tokom vegetacionog perioda, sorte i njihove interakcije. TN se kretala od 40kg ha-1 u nepovoljnim do 93kg ha-1 u povoljnim proizvodnim uslovima. Razlika između sorti u TN bila je u korelaciji sa akumuliranom m&som suve materije i usvojenim N do cvetanja (R2>0,70). ETN je varirala vise između proučavanih sorti (0,27-0,66) nego između godina ispitivanja (0,47-0,52). TN je bila u negativnoj korelaciji sa količinom N usvojenim posle cvetanja. NHI je varirao između sorti u intervalu 0,49-0,73 a između godina u intervalu 0,57-0,74. NHI kod sorti Arapiles, Schooner, Cantala, Kaskade i Rek je bio viši od 0,70, a kod sorte Hiproly niži od 0,50. Zavisno od godine, odnosno od spoljašnjih činilaca, translocirani N je predstavljao od 41 do 85% N zrna. Efikasnost iskorišćavanja N iz vegetativnog dela u sintezi proteina zrna može se uspešno odrediti na osnovu koncentracije N u slami. Pošto se radi o jeftinoj i jednostavnoj analizi, koncentracija N u slami može biti primenjena u testiranju obimnog oplemenjivačkog materijala.