Optimum Castor Meal Application in the Cultivation of Pak Choi (Brassica chinensis L.) with Toxicity Survey for Earthworms (Eisenia andrei)

In Taiwan, castor meal (CM) is often used by farmers as an organic fertilizer for the supplement of plant nutrition. It can rapidly increase nitrogen availability for crops. However, the excessive application of CM will affect the ecosystem. This study was conducted to evaluate the optimum concentration of CM that can be used as a fertilizer for balancing crop production and soil ecosystem health (by considering earthworms). Pak choi was selected for the experiment. A randomized block design with three replications was used, with treatments consisting of five concentrations of CM (namely 25, 50, 100, 150, and 200 kg/0.1 ha) and fermented livestock compost 800 kg/0.1 ha, represented as CM25, CM50, CM100, CM150, CM200, and LC800, respectively. The results revealed that soil properties, leaf nutrient concentration, and plant traits, namely plant diameter, plant height, and fresh and dry root and shoot matter, improved with the increasing concentrations of CM, and CM100–CM200, and led to the highest production of pak choi which was equivalent to that with LC800. However, the weight of earthworms decreased as CM concentrations increased. The weight of earthworms was similar between CM25, CM50, CM100, and LC800. In conclusion, given the characteristics of high nitrogen as a fertilizer, the optimal dose of CM was 100–150 kg/0.1 ha for obtaining a balance between crop production and ecosystem safety.

Genetic diversity in Coffea canephora genotypes for leaf nutrient concentration

This study analyzed the genetic diversity in Coffea canephora genotypes by univariate and multivariate statistical analysis, based on concentrations of macro- and micronutrients in coffee leaves in the stages of pre-flowering and grain filling. The experiment was arranged in randomized blocks with three replications, in a 42x2 factorial design, in which factor one represented the evaluated genotypes and factor two the periods of leaf sampling, i.e., pre-flowering and grain filling. The data of leaf nutrient concentrations were subjected to analysis of variance by the F test (p <0.01), and genetic parameters were estimated. For the study of genetic diversity, the genotypes were grouped by the hierarchical unweighted pair-group method using arithmetic averages (UPGMA). The relative importance of a trait to predict genetic diversity was also studied. There is genetic divergence for leaf nutrient concentration in C. canephora genotypes. With a maximum limit of 60% of dissimilarity between genotypes, four groups were also formed by UPGMA. For the 42 evaluated genotypes, leaf S concentration was the most important trait for genetic diversity; this genotypic variability should be investigated to enhance the efficiency of nutritional diagnosis. Highlights There is genetic variability for leaf nutrient concentration in Coffea canephora The leaf concentration of nutrients in the phenological stage of pre-anthesis is different from the leaf concentration of nutrients in the coffee bean filling period. Leaf concentration of sulfur was the characteristic that contributed most to the genetic diversity among the 42 genotypes, followed by the concentration of copper, boron and magnesium. Genotypic variability for leaf nutrient concentration should be considered for better nutritional management.

Cultivar-rootstock interactions on growth, yield and mineral nutrition of newly planted peach trees in a pot experiment

Two peach cultivars, i.e. ‘Andross’ and ‘Mercil’ were budded onto four rootstocks of varying vigor (‘Garnem’, ‘GF 677’, ‘Rootpac R’ (RPR) and ‘Rootpac 20’ (RP20)) and planted in pots. The plants were grown for three years, and each year the growth of the trees (in terms of trunk cross sectional area, tree height, and shoot length), fruit production and leaf nutrient concentration were assessed. The rootstock exerted a significant effect on the above-measured variables, as the lowest tree height in both cultivars was recorded when these were grafted on RP20 (the most dwarfing rootstock of all four used). The yield per tree was highest when the most vigorous rootstocks. ‘Garnem’ resulted in the highest upper plant dry weight, while ‘RP20’ in the lowest. Cultivar exhibited a significant effect regarding leaf nutrient concentration, as ‘Andross’ presented higher concentrations of N, K, Ca and Fe in most combinations and lower concentrations of P and Cu. The discriminant analysis, using all growth and nutrient data from the last two years, revealed that irrespective of the cultivar budded, ‘RP20’ and ‘GF 677’ were clearly distinguished from each other and from ‘RPR’ and ‘Garnem’. On the other hand, the hierarchical agglomerative analysis pointed out the crucial role of ‘RP20’ and ‘Garnem’ on tree growth and leaf nutrient concentration, with the cultivar budded on them playing a minor role. In conclusion, the fertilization program of a young, newly established orchard, should take into account the singularity of each scion-rootstock combination, to achieve the optimum tree performance.