Phosphorus and Biomass Distribution, and P-efficiency by Diverse Brassica Cultivars Exposed to Adequate and P-stress Environment

To acclimate under orthophosphate (Pi) starved environment, plant species and cultivars display an elegant myriad of Pi-adaptive and rescue responses via reprioritizing internal Pi use and maximizing external Pi acquisition by reprogramming metabolism and restructuring root system architecture.Exploitation of considerable genetic diversity both between and within crop species and harnessing of these genetic variations can lead us to develop smart plants with improved P-acquisition, growth and yield under P-deprivation. To elucidate the effect of P-stress on plant growth, and P-efficiency under Pstarvation, 14 diverse Brassica cultivars were grown hydroponically in a climatically controlled chamber using sufficient (200 and 400 μM) and stress (10 and 20 μM) P-levels using ammonium phosphate (NH4H2PO4) as a P source. Cultivars showed differential growth behaviour in terms of biomass accumulation (shoot and root dry matter partitioning), percent distribution of Pi-concentration ([P]) and P-contents in plant parts (roots and shoots), and P-efficiency ratio (% PER)(relative shoot growth) indicating considerable genetic diversity among the tested Brassica cultivars. PER and the proportional increases in shoot dry matter (SDM) accumulation (SDMmax/SDMmin) in response to the P levels assisted in categorizing the cultivars into efficient and inefficient utilizers of the absorbed P from an ambient environment. Cultivars were classified into efficient responsive (ER), efficient non-responsive (ENR), non-efficient responsive (NER) and non-efficient non-responsive (NENR) by plotting ordination plots between PER and SDMmax/SDMmin under P-stress environment. Differential PER values at stress P levels corresponds to high P levels suggest that P efficiency mechanisms can be different from one cultivar to another within a give plant species and cultivars exhibiting high PER values are better choice to thrive under P-starvation.