Essential plant nutrients are mainly applied to soil and plant foliage for achieving maximum economic yields. Soil application method is more common and most effective for nutrients, which required in higher amounts. However, under certain circumstances, foliar fertilization is more economic and effective. Foliar symptoms, soil and plant tissue tests, and crop growth responses are principal nutrient disorder diagnostic techniques. Soil applications of fertilizers are mainly done on the basis of soil tests, whereas foliar nutrient applications are mainly done on the basis of visual foliar symptoms or plant tissue tests. Hence, correct diagnosis of nutrient deficiency is fundamental for successful foliar fertilization. In addition, there are some more requirements for successful foliar fertilization. Foliar fertilization requires higher leaf area index for absorbing applied nutrient solution in sufficient amount, it may be necessary to have more than one application depending on severity of nutrient deficiency. Nutrient concentration and day temperature should be optimal to avoid leaf burning and fertilizer source should be soluble in water to be more effective. Foliar fertilization of crops can complement soil fertilization. If foliar fertilization is mixed with postemergence herbicides, insecticides, or fungicides, the probability of yield response could be increased and cost of application can be reduced.

Lowland rice is a staple food for more than 50% world population. Iron toxicity is one of the main nutritional disorders, which limits yield of lowland rice in various parts of the world. The toxicity of iron is associated with reduced soil condition of submerged or flooded soils, which increases concentration and uptake of iron (Fe 2+ ). Higher concentration of Fe 2+ in the rhizosphere also has antagonistic effects on the uptake of many essential nutrients and consequently yields reduction. In addition to reduced condition, increase in concentration of Fe 2+ in submerged soils of lowland rice is associated with iron content of parent material, oxidation-reduction potential, soil pH, ionic concentration, fertility level, and lowland rice genotypes. Oxidationreduction potential of highly reduced soil is in the range of -100 to -300 mV. Iron toxicity has been observed in flooded soils with a pH below 5.8 when aerobic and pH below 6.5 when anaerobic. Visual toxicity symptoms on plants, soil and plant tissue test are major diagnostic techniques for identifying iron toxicity. Appropriate management practices like liming acid soils, improving soil fertility, soil drainage at certain growth stage of crop, use of manganese as antagonistic element in the uptake of Fe 2+ and planting Fe 2+ resistant rice cultivars can reduce problem of iron toxicity.

Background: Rice (Oryza sativa L.) germplasm represents an extraordinary source of genes that control traits of agronomic importance such as drought tolerance. This diversity is the basis for the development of new cultivars better adapted to water restriction conditions, in particular for upland rice, which is grown under rainfall. The analyses of subtractive cDNA libraries and differential protein expression of drought tolerant and susceptible genotypes can contribute to the understanding of the genetic control of water use efficiency in rice.

Cosmopolitan pests such as Brevicoryne brassicae, Lipaphis pseudobrassicae, and Myzus persicae (Aphididae) cause significant damage to Brassicaceae crops. Assessment of the important biotic and abiotic factors that regulate these pests is an essential step in the development of effective Integrated Pest Management programs for these aphids. This study evaluated the influence of leaf position, precipitation, temperature, and parasitism on populations of L. pseudobrassicae, M. persicae, and B. brassicae in collard greens fields in the Triângulo Mineiro region (Minas Gerais state), Brazil. Similar numbers of B. brassicae were found on all parts of the collard green plants, whereas M. persicae and L. pseudobrassicae were found in greatest numbers on the middle and lower parts of the plant. While temperature and precipitation were positively related to aphid population size, their effects were not accumulative, as indicated by a negative interaction term. Although Diaeretiella rapae was the main parasitoid of these aphids, hyperparasitism was dominant; the main hyperparasitoid species recovered from plant samples was Alloxysta fuscicornis. Parasitoids seem to have similar distributions on plants as their hosts. These results may help predict aphid outbreaks and gives clues for specific intra-plant locations when searching for and monitoring aphid populations.

Drought stress, particularly during the flowering and grain-filling stages of growth, contributes to serious yield loss in common bean (Phaseolus vulgaris L.). The aim of this study was to identify genes induced in response to drought stress using transcriptome analysis of contrasting genotypes. Using leaf tissues of tolerant (BAT 477) and susceptible common bean genotypes (Pérola), collected at the flowering and grain-filling stages, four complementary deoxyribonucleic acid representational difference analysis subtractive libraries were constructed and then sequenced. A total of 7,203 (77.6 %) sequences with an average sequence size of 570 bp were considered valid, for a combined 4 Mbp sequence. According to a differential display analysis, 802 expressed sequence tags, distributed across 67 contigs, were differentially expressed by the tolerant (37 contigs) and susceptible genotypes (30 contigs) after identification under drought conditions during the two investigated plant developmental stages. Of these differential contigs, the 13 most frequent genes were exclusive to the tolerant genotype. Based on BLAST2GO, 73 % of the gene sequences were annotated and 12 % showed mapping results, with the highest similarity rate corresponding to Glycine max (41 %). According to gene ontology functional analysis, 48 % of the sequences were attributed to cell metabolic processes. Overall, 8.3 % of the transcribed sequences exhibited similarity to transcription factors, predominantly those of the AP2-EREBP family (97.8 %). Of the target sequences validated by quantitative real-time polymerase chain reaction, most genes showed an expression level that agreed with that predicted by in silico analysis. Thus, the drought transcriptome dataset is a valuable Electronic supplementary material The online version of this article