Evaluation of Bangladeshi Rice Genotypes and Improved lines for Shoot Biomass under higher levels of Phosphorus Deficiency at vegetative stage

Abstract

Phosphorus is vital nutrient for the plant growth, and inevitable to maintain the yield of rice. Current practices of chemical phosphorus fertilization is not sustainable because of its limited sources and non-renewable nature together with higher expenses. Breeding low phosphorus tolerant or resistant with higher uptake and assimilation efficient rice variety is the best alternative for sustainable production. This study aimed to evaluate the selected Bangladeshi rice germplasms and improved lines under phosphorus deficient soil to know their level of deficiency tolerance or resistance. A total of 28 rice genotypes from various ecotypes such as Aus, Aman, Boro and Jhum were collected and grown in pot contained highly phosphorus deficient soil in the rooftop polythene shed house during October 2019 to March 2020. A phosphorus deficiency susceptible variety, IR 64, was used as control, and experiment was conducted following randomized complete block design with two replications. Biomass related traits such as dry weight (DW) and relative dry weight (RDW, %) were analyzed at early vegetative stage. Visual score based on the responses to artificial drought occurred appeared due to absence of water for 5 consecutive days because of government imposed Covid-19 lockdown were also evaluated in a scale of 0 to 4. Plants showed wide variation in the measured traits in both in the phosphorus added normal or phosphorus deficient conditions. Two patterns of responses were observed. One patterns was similar to susceptible control IR 64 and another is highly sensitive to P- deficiency. Cluster analysis resulted four groups (I to IV). Group I consist of 4 rice cultivar including Pathar kuchi, lal dhan, INL-9 and 30, and showed lower DW under both phosphorus added & deficient conditions together with higher susceptibility to artificial drought. IR 64 belongs to the Group- II together with Murali, Kuti Agrani, Kernaicha and other 5 INLs. They have higher DW in phosphorus added condition but very low RDW in phosphorus deficient condition and also susceptible to artificial drought. Group III cultivars have medium DW under phosphorus added and low RDW under phosphorus deficient condition and Kali jira and Aus (Awned) are belong to this group. Two jhum variety, Renkhoa Dhan and Galongpru and 7 INLs are belong to the group IV which has moderate to high RDW under both phosphorus added and phosphorus deficient conditions. Rice cultivars of this group showed higher levels of tolerance to artificial drought and are promising for further breeding program to develop phosphorus deficiency tolerant variety.