Zvonimir Štafa

Yield and height of alfalfa (Medicago sativa L.) effected by rhizobial inoculation

Forage crops constitute the major component of dairy feeds and legumes have been viewed as excellent sources of N in agriculture.Biological nitrogen fixation by leguminous plants is a significant source of available N in both natural and managed ecosystems and that unique ability makes legumes especially valuble in forage program.Alfalfa is one of the most important protein sources for nutrition of livestock.As a legume, alfalfa forms symbiotic relation with nitrogen fixing bacteria Sinorhizobium meliloti, which symbiotic efficiency is determined by their individual genotype.The aim of this study was to determine the infuence of cultivar type of alfalfa and S.meliloti strain on forage yield and height of plants.Results of 2 years experiment revealed that DM yield was significantly higher with cultivars OS 88 and Mirna compared to other two cultivars (Posavina and OS 66). The effect of cultivars by strains was not significant, so inoculated cultivars performed significantly better DM yields in comparison to control (no inoculation).

Biomass production and ethanol potential from sweet sorghum in Croatia.

Maize (Zea mays L.) genotypes wit It improved nitrogen utilization efficiency (NUE) are of interest to growers. Field experiments were conducted to evaluate the total N uptake in the aboveground biomass and NUE (kg grain per kg of N absorbed in the aboveground biomass). Four commercial hybrids of similar maturity ranking were grown under the high-N (200 kg N ha(-1)) and low-N (1100 kg N ha(-1)) fertilization rates over three years. Growing conditions significantly affected hybrid performance for NUE, which ranged from 42 kg grain kg N-1 in the low-yielding (dry) environment to 55 kg grain kg N-1 under higher yielding environment, When compared to the low-N rate, the average N uptake was by 32% higher at the high-N rate, whereas smaller differences occurred for the aboveground biomass (12%), grain yields (14%), stover N (28%) and grain N (13%) concentrations. Significant differences existed among tested hybrids for grain yield, aboveground biomass, grain and stover N concentration, N uptake and consequently NUE.Hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnatum L.) were evaluated as cover crops during two vegetation seasons in the Mediterranean and Continental area of Croatia. Better tolerance to low winter temperatures was observed for crimson clover. Higher plants (10 to 3 1 cm) before winter and in spring (67 to 117 cm) were measured for hairy vetch, while crimson clover had higher yields of fresh biomass (33.7 to 113.1 t ha(-1)). Concentrations of N (1.53 to 3.34%), P2O5 (0.55 to 1.04%) and K2O (2.02 to 5.32%) in plant tissue were higher for hairy vetch. However, due to higher yields of dry matter, crimson clover accumulated more N (105 to 239 kg ha(-1)), P2O5 (28 to 83 kg ha(-1)), and K2O (105 to 440 kg ha(-1)) than hairy vetch. According to our results crimson clover could be recommended as a cover crop in Mediterranean and Continental area of Croatia.

The effect of harvest date on forage production and crude protein yield of forage pea and small grain cereal mixtures

This research was conducted to determine how forage yield and crude protein (CP) concentration of forage pea-rye (Secale cereale L.), forage pea-triticale (X Triticosecale rimpaui Wittm.) and forage pea-wheat (Triticum aestivum L.) intercrops are affected by harvest at two small grain cereals growth stages (milk and soft-dough).The base seeding rate used in this study was 100 seeds m-2 of forage pea in mixture with 200 seeds m-2 of each cereal. A summary of production treatments involved: fertilisation before plowing (40 kg N ha-1, 130 kg P ha-1, 130 kg K ha-1), plowing at 30 cm, granular topdressing 2 x 30 kg N ha-1. In the early flowering stage of forage pea DM yield was significantly (P=0, 05) lower than when it was cut in early seed vegetative stage. The highest forage pea DM yield was obtained in mixture with wheat. Triticale in mixture with forage pea gained significantly the highest yield of DM among all small grain cereals, and that affected in great portion total DM yield that was also significantly highest with that mixture. In the early flowering stage of forage pea CP yield was significantly lower than when it was cut in early seed vegetative stage. The highest forage pea CP yield was obtained in mixture with wheat. All cereals in mixtures with forage pea significantly better yielded in late boot vegetative stage compared to early head. The conclusion of this research is that the highest yield of DM and CP was obtained with the mixture of forage winter pea and triticale.