The root system of permanent grasslands is of outstanding importance for resource acquisition. Particularly under semi-arid conditions, the acquisition of water and nutrients is highly variable during the vegetation growth period and between years. Additionally, grazing is repeatedly disturbing the functional equilibrium between the root system and the transpiring leaf canopy. However, very few data is available considering grazing effects on belowground net primary productivity (BNPP) and root-shoot dry mass allocation in natural grassland systems. We hypothesise that grazing significantly reduces BNPP due to carbon reallocation to shoot growth. Root biomass and BNPP were estimated by soil coring in 2004, 2005 and 2006 and from ingrowth cores in 2005 and 2006 at one site which has been protected from grazing since 1979 (UG79), at one winter grazing (WG), and one heavily grazed (HG) site. BNPP was estimated from the summation of significant increments of total and live root biomass and from accumulated root biomass of ingrowth cores. Belowground biomass varied from 1,490-2,670 g m −2 and was significantly lower under heavy grazing than at site UG79. Root turnover varied from 0.23 to 0.33 year −1 and was not significantly different between sites. Heavy grazing significantly decreased live root biomass and BNPP compared to site UG79. Taking BNPP estimates from live root biomass dynamics and ingrowth cores as the most Plant Soil (2008) 307:41-50 reliable values, the portion of dry mass allocated belowground relative to total net primary productivity (BNPP/NPP) varied between 0.50-0.66 and was reduced under heavy grazing in 2005, but not in 2006. The positive correlation between cumulative root length density of ingrowth cores and leaf dry matter suggests that the ingrowth core method is suitable for studying BNPP in this semi-arid steppe system. Grazing effects on BNPP and BNPP/NPP should be considered in regional carbon models and estimates of belowground nutrient cycling.

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APETALA2/Ethylene-Responsive Factor (AP2/ERF) gene family is plant specific transcription factor. It plays critical roles in development process, tolerance to biotic and abiotic stresses, and responses to plant hormones. However, limited data are available on the contributions of AP2/ERF gene family in barley (Hordeum vulgare L.). In the present study, 121 HvAP2/ERF genes in barley were identified by using bioinformatics methods. A total of 118 HvAP2/ERF (97.5%) genes were located on seven chromosomes. According to phylogenetic classification of AP2/ERF family in Arabidopsis, HvAP2/ERF proteins were divided into AP2 (APETALA2), RAV (Related to ABI3/VP), DREB (dehydration responsive element binding), ERF (ethylene responsive factors) and soloist sub families. The analysis of duplication events indicated that tandem repeat and segmental duplication contributed to the expansion of the AP2/ERF family in barley. HvDREB1s/2s genes displayed various expression patterns under abiotic stress and phytohormone. Taken together, the data generated in this study will be useful for genome-wide analysis to determine the precise role of the HvAP2/ERF gene during barley development, abiotic stress and phytohormone responses with the ultimate goal of improving crop production.

Manually delaying pollination in maize restricted kernel growth and induced abortion by suppressing cell wall invertase activity and repartitioning assimilates.