Gordana Bukvić

Response of red clover to phosphorus fertilization

Introduction Red clover is a perennial legume, productive for 2 to 3 years. Maximum yields and the highest quality are realised in the second year of its life if the first cutting is done in early flowering (20%) and further cuttings about 45 days after the previous cut (Wiersma et al., 1998). Red clover is a highly adaptable species to various climatic conditions and soil types and therefore grows widely in numerous regions of the world (Ball et al., 1996). According to the FAO data (Statistical Databases, 2000), red clover totalled almost 2.5 million hectares in the world. Most frequently is sown at less intensively used soils (Frame et al., 1998) with moderate wet and cold weather and shorter vegetation. These conditions are dominant in mountain parts of Croatia, which take 47% of state land area (Knezevic et al., 1995). The aim of the investigation was to evaluate the possibility to establish red clover at acid, potassium-poor and extremely phosphorous-poor soil of Croatian mountain region after several years of ameliorative fertilization with P2O5. Yield of hay and content of macro and microelements in plant dry matter were examined.

Phosphorus, calcium and magnesium status in maize genotypes grown on acid soil

The response of five maize inbred lines and their three commercial hybrids to acid soil with low nutrients availability were studied in a field trial over a three year period (2003 to 2005) in the east Croatia. Grain yield and P, Ca and Mg concentration in leaves were analysed. Highly significant effects of the both, year and genotype for all traits were determined. Grain yield of maize genotypes ranged from 5.11 t ha-1 in dry year to 7.39 t ha-1 in more favourable year. Regardless of low soil P content, an adequate P status (3.17 g kg-1) in maize were found, while lower Ca (5.62 g kg-1) and Mg (2.36 g kg-1) mean concentrations in leaves are consequences of their low level in soil. However, considerable differences in P, and especially Ca and Mg status were found among parental lines, what was reflected on their progeny. The results indicated that origin of inbred line may have an important role for nutrient content inheritance.