Variation in seed nutrient content, seedling growth and yield of rice varieties grown in a paddy field without application of fertilisers for forty years

Abstract

Knowledge on the growth of rice (Oryza sativa L.) in low-fertility field conditions is essential to ensure their sustainability and enhance productivity. The key variables determining the productivity of such systems were studied in 40 recommended rice varieties grown in a low-fertile field. The paddy field had received no form of fertiliser or straw for the past 40 years, but it was used for rice cultivation two times per year under other standard crop-management practices. Harvests were made at 6 weeks after planting and at physiological maturity. The same varieties were also grown for 14 days in glass boxes containing distilled water only. Stepwise regression was used to identify the important variables for predicting dry weight (DW) at 14 days, 6 weeks and maturity. Thousand-seed weight and seed phosphorus (P) content of seed paddy (grains used for planting) had strong positive correlations with DW of seedlings after 14 days (r = 0.91, P < 0.0001) and 6 weeks (r = 0.7, P < 0.0001), respectively. However, initial growth performances did not correlate well with aboveground DW or grain yield at maturity. DW at maturity positively correlated with time taken to maturity (r = 0.78, P < 0.0001), shoot K content (r = 0.28, P = 0.008), root DW (r = 0.22, P < 0.02), and uptake rates of K (r = 0.32, P < 0.01) and P (r = 0.33, P < 0.01) at 6 weeks. Seed N concentration decreased (r = −0.63, P < 0.001) and growth rate increased (r = 0.65, P < 0.001) with time taken to maturity. Although seed weight and seed P content of rice are key determinants of early crop establishment, capacity to produce large roots, amount of K taken up, P and K uptake rates at 6 weeks, and time taken to maturity are the key determinants of maturity biomass and grain yield in low-fertile field conditions.

Plant DNA methylation is sensitive to parent seed N content and influences the growth of rice

“…Some previous studies suggest that early growth guarantees higher biomass and grain yield under optimal management conditions [ 42 , 43 ], while others report that early vigorous growth does not ensure a higher yield at maturity [ 44 ]. Mayamulla et al (2017) reported that dry weight of rice in low-fertility field conditions correlated well with seed phosphorus content but less with seed N concentration [ 44 ]. In our study, HPSN led to better seedling growth and resulted in higher grain yield and N content in Ox1 under the N fertilizer condition.…”

Rice production in nutrient-limited soils: Strategies for improving crop productivity and land sustainability

“…Declining soil fertility is one of the main factors for stagnating rice yields in Africa and Asia (Timsina & Connor, 2001;Dobermann et al, 2002;Saito & Futakuchi, 2009;Weerakoon et al, 2011;Rodenburg et al, 2014;Katsura et al, 2016;Mayamulla et al, 2017;Stewart et al, 2020). This has been caused to a considerable extent by the continuous crop and residue removal, negative nutrient balances and soil degradation (Cassman et al, 1998;Dobermann et al, 2002;Nhamo et al, 2014;Kekulandara et al, 2019).…”

“…Even though improving soil fertility to achieve high productivity is desirable, one of the main problems faced by many rice farmers in Asia and Africa is the difficulty in applying recommended rates of synthetic fertilisers. This is due to their poor economic status, high fertiliser costs, unavailability of inputs, and/ or production risks (Weerakoon et al, 2011;Haefele et al, 2003Haefele et al, , 2014Nhamo et al, 2014;Mayamulla et al, 2017;Stewart et al, 2020).…”

Degree-day requirement for heading and maturity of three most popular rice varieties in Sri Lanka as influenced by location and season

“…Therefore, the degree-day required for heading, ripening and maturity differed largely among locations and affected by T min . As reported in literature, soil characteristics such as fertility and moisture availability may also contribute to determine the timing of developmental events (Sahrawat et al, 1995;Franks, 2011;Mayamulla et al, 2017). However, the sensitivity of crop development to location-specific soil characteristics was largely ignored when calculating degree days.…”

“…However, the sensitivity of crop development to location-specific soil characteristics was largely ignored when calculating degree days. It is reported that, development events may either be advanced or delayed depending on the limitation in soil e.g., early heading was observed when nitrogen or moisture limitations were occurred (Kleinig and Noble, 1967;Franks, 2011;Minh-Thu et al, 2018;Ye et al, 2019), whereas development events were delayed under phosphorus deficiency (Sahrawat et al, 1995;Mayamulla et al, 2017). Thus, the potential impact of soil in determining the timing of development events such as heading cannot be ignored for field grown crops.…”