Efficient phosphorus application strategy to improve rice yields under cold stress-prone and P-deficient environments

Related Research Project

SATREPS Madagascar

Country

Madagascar

Description

Despite a general perception that phosphorus (P) deficiency delays phenological development in annual crops, the impacts of interaction between this phenological delay and climatic conditions on crop productivity remain poorly understood. On-farm experiments were conducted in the central highlands of Madagascar, where P deficiency and late-season low temperature stress frequently restrict rice yields. Rice X265 was grown under four different fertilizer treatments with different combinations of N and P during early and late transplanting dates (ETP and LTP, respectively). Plants subjected to no fertilizer or single N treatments (-P) showed delayed heading by 9–16 days relative to the single P and N and P combined plots on average (Table 1). The delay in phenological development without P application (-P) and the delay in transplanting date (LTP) additively increased the risk of low temperature stresses at the heading periods (Fig. 1). As a result, -P plots at LTP increased the cooling degree days and spikelet sterility while the delay in phenological development without P application little affected the cooling degree days and spikelet sterility when transplanted early or ETP (Fig. 2). With this significant interaction between P application and transplanting dates on cold stresses, the effect of P on rice yield was much greater in LTP than in ETP because P application alleviated not only P deficiency but low temperature stress as well by shortening day to heading (Table 1). This study provides field evidence that the effects of P application on rice yield were greatly dependent on transplanting date via their impact on phenological development under P-deficiency in climate stress-prone environments. Changes in phenological development due to plant nutrient status and its interaction with climate-induced stress needs further attention for improving fertilizer management practice.

Figure, table

Table 1. Effect of P application and transplanting date on days to heading and yield of rice grown on P-deficient fields
- -P indicates the means of the plots without fertilizer and with N applied as urea at the rate of 80 kg N ha^-1.
- +P indicates the means of plots with P applied as triple super phosphate at the rate of 50 kg P₂O₅ ha^-1 and with N and P combined.
- ETP refers to early transplanting plots (November 2829). LTP refers to late transplanting plots (December 27–30).
- Underlined values indicate significant differences between -P and +P plots at 5% by Tukey HSD.
- ANOVA detected a significant interaction between P treatment and transplanting dates on yield.
Fig. 1. Changes in daily mean temperatures at the heading periods as affected by transplanting dates and P application
Fig. 2. Effect of transplanting dates and P application on the cooling degree days (CDD) and spikelet sterility
CDD is the sum of daily mean temperatures below 22ºC from 15 days before to 7 days after heading.

Figures and table reprinted/modified with permission from Andrianary et al. (2021).