EcoMeristem, a model of morphogenesis and competition among sinks in rice. 2. Simulating genotype responses to phosphorus deficiency

Abstract

Phenotypic plasticity enables plants to adjust their morphology and phenology to variable environments. Although potentially important for crop breeding and management, the physiology and genetics of plasticity traits are poorly understood, and few models exist for their study. In the previous paper of this series, the structural–functional model EcoMeristem was described and field validated for vegetative-stage rice. This study applies the model to an experimental study on phosphorus deficiency effects on two morphologically contrasting rice cultivars, IR64 and Azucena, grown in controlled environments under hydroponics culture. Phosphorus deficiency caused severe biomass growth reductions in the shoot but not in the root, thus increasing the root / shoot weight ratio. It also inhibited tiller formation and leaf elongation, prolonged the phyllochron, and increased carbohydrate reserve pools in the plant. Analysis aided by the model identified inhibition of leaf extension and tillering as primary effects of the stress. Physiological feedback probably led to longer phyllochron, greater reserve accumulation and root growth stimulation. The main effect of P deficiency appeared to be a reduction in demand for assimilates in the shoot while photosynthetic radiation use efficiency remained nearly constant, resulting in spill-over of excess assimilates into reserve compartments and root growth. The results are discussed in the light of future applications of EcoMeristem for phenotyping and genetic analyses of phenotypic plasticity.

Developmental and growth controls of tillering and water-soluble carbohydrate accumulation in contrasting wheat (Triticum aestivumL.) genotypes: can we dissect them?

“…The timing of transition of the apex to the reproductive stage, which depends on the combination of genes regulating flowering time and the interaction with photoperiod and temperature, also influences tillering and C allocation (Hay and Kirby, 1991). The availability of carbohydrates for new tillers versus their demand was a key factor behind the final tiller number of wheat (Rodriguez et al ., 1998), rice (Dingkuhn et al ., 2006), and sorghum in different environments (Kim et al ., 2010 b ) or across genotypes contrasting for tillering (Kim et al ., 2010 a ). The maximum tiller number per plant and survival after the onset of stem elongation have been linked to an increased demand by main shoots with high leaf area in sorghum (van Oosterom et al ., 2010 b ).…”

Performance of low phosphorus tolerant rice genotypes under drought stress

“…According to Dingkuhn et al (2006), the main effect of P deficiency appeared to be a reduction in demand for assimilates in the shoot while photosynthetic radiation use efficiency remained nearly constant; resulting in spillover of excess assimilates into reserve compartments and root growth. Increased root growth relative to shoot was associated with increased sucrose concentration in roots, and thus possibly resulted from assimilates liberated by shoot growth inhibition (Luquet et al, 2005).…”

Performance of Some Promising Egyptian Rice Genotypes Under Diffrenet Locations

“…Grain yield depends on genotype, environment and their interaction with each other. Under the same management conditions, variation in grain yield is principally explained by the effects of genotype and environment (Dingkuhn et al, 2006). Interaction between these two explanatory variables gives insight for identifying genotype suitable for different environments.…”