Plant mineral nutrition in crop production

International audienc

Genetic control of interactions among individuals: contrasting outcomes of indirect genetic effects arising from neighbour disease infection and competition in a forest tree

Indirect genetic effects (IGEs) are heritable effects of individuals on trait values of their conspecifics. IGEs may substantially affect response to selection, but empirical studies on IGEs are sparse and their magnitude and correlation with direct genetic effects are largely unknown in plants. Here we used linear mixed models to estimate genetic (co)variances attributable to direct and indirect effects for growth and foliar disease damage in a large pedigreed population of Eucalyptus globulus. We found significant IGEs for growth and disease damage, which increased with age for growth. The correlation between direct and indirect genetic effects was highly negative for growth, but highly positive for disease damage, consistent with neighbour competition and infection, respectively. IGEs increased heritable variation by 71% for disease damage, but reduced heritable variation by 85% for growth, leaving nonsignificant heritable variation for later age growth. Thus, IGEs are likely to prevent response to selection in growth, despite a considerable ordinary heritability. IGEs change our perspective on the genetic architecture and potential response to selection. Depending on the correlation between direct and indirect genetic effects, IGEs may enhance or diminish the response to natural or artificial selection compared with that predicted from ordinary heritability

Karyological investigations on several species of genus Rebutia

Abstract These are the first avaiable data about the karyology of the taxa belonging to Rebutia Sect. Digitorebutia, the section of genus Rebutia K. Schum. with more species. Eight species of Sect. Digitorebutia were investigated. Out of the species studied, seven (R. pygmaea, R. raulii, R. steinmannii, R. major, R. diersiana, R. haagei and R. gavazzii) are polyploid, with tetraploid chromosome number 2n=4x = 44, and one (R. leucanthema) is diploid, with chromosome number 2n=2x = 22; x = 11. This is the first karyotype information of all the species investigated

Boron affects the growth and ultrastructure of castor bean plants Boro afeta o crescimento e a ultra-estrutura da mamoneira

The cultivation of oleaginous plants like the castor bean guarantees employment for agricultural families and can contribute in energy and chemical sectors, especially in the northeastern semi-arid regions of Brazil. Boron (B) deficiency is a widespread nutritional disorder despite the fact that various anthropogenic sources with high B content may increase soil B to toxic levels for plants. The present study was designed to investigate the ultrastructural effects of boron deficiency and toxicity on castor bean plants which were grown under greenhouse condition using plastic containers with 10 L of nutrient solution. Boron treatments comprised: control (no B); 0.27 mg L-1, 5.40 mg L-1 B pots (one plant per pot), tested in a completely randomized design with three replicates. The dry matter of all plant parts and B concentration were determined. Cellular ultrastructure was evaluated by transmission and scanning electron microscopy on samples of leaves and petioles. Dry matter yield was affected by the B absence treatment but there was no difference for the 5.4 mg L-1 B (toxic conditions) treatment. A marginal leaf burn at edge and tips of oldest leaves and absence of starch granules in chloroplasts were noted for the B toxicity treatment. The deformation of the youngest leaves, the death of the apical meristem as well as the swelling of the middle lamella, absence of starch granules in chloroplasts and petiole vessels untidily were observed in the B absent treatment. It is concluded that the production and development of castor bean plants is affected by boron deficiency, but not for boron toxicity conditions.<br>A mamoneira é uma oleaginosa com grande potencial para a geração de renda na agricultura familiar e para produção de matéria prima para a indústria química e setor energético brasileiro, especialmente em regiões do semi-árido nordestino. A deficiência de boro (B) ocorre de forma generalizada no Brasil e a aplicação excessiva deste micronutriente pode causar toxicidade. Este estudo avalia o desenvolvimento e os efeitos ultra-estruturais de deficiência e toxicidade de boro em mamoneira. O experimento foi realizado em condições de casa de vegetação, com vasos de 10 L de solução nutritiva. Foram utilizados três tratamentos: testemunha (sem B); 0,27 e 5,40 mg L-1 B, uma planta por vaso, em delineamento experimental inteiramente ao acaso com três repetições. A produção de matéria seca de cada parte da planta foi avaliada e o teor de boro determinado. Foram observados os efeitos morfológicos e as alterações na ultra-estrutura celular nas folhas e pecíolos, através da técnica de microscopia eletrônica de transmissão e varredura. A produção de matéria seca da mamoneira foi afetada em condições de deficiência de boro, mas não em condições de toxicidade (5,4 mg L-1 B). Neste último tratamento foram constatadas cloroses nos bordos de folhas velhas e ausência de grânulos de amido. Na omissão de boro, as plantas apresentaram deformação de folhas novas, morte do meristema apical, engrossamento da lamela média, ausência de grânulos de amido nos cloroplastos e desorganização dos vasos condutores do pecíolo. O desenvolvimento e a produção da mamoneira são afetados em condições de deficiência de boro mas não na condição de toxicidade