The nitrogen topdressing mode of indica-japonica and indica hybrid rice are different after side-deep fertilization with machine transplanting

Abstract

Determination of the optimal fertilization method is crucial to maximize nitrogen use efficiency and yield of different rice cultivars. Side-deep fertilization with controlled-release nitrogen, in conjunction with machine transplanting and subsequent topdressing, was applied to Indica–japonica hybrid rice ‘Yongyou1540’ (YY1540) and indica hybrid rice ‘Tianyouhuazhan’ (TYHZ). Four nitrogen treatments were applied in 2018 and 2019: traditional nitrogen application with quick-release nitrogen (T1), single-dose deep fertilization at transplanting with 100% controlled-release nitrogen (T2), and deep fertilization of 70% controlled-release nitrogen and topdressing of 30% quick nitrogen at tillering (T3), or at panicle initiation (T4). Side-deep fertilization reduced the fertilizer application frequency without causing yield loss, T4 enhanced the yield of YY1540 by increasing the number of productive tillers and number of spikelets per panicle compared with T1, T2 and T3. The yield of TYHZ showed no significant difference among treatments. The T4 treatment decreased the number of tillers at the tilling peak stage and increased the percentage productive tillers and number of differentiated spikelets. Compared with the other treatments, T4 increased dry matter accumulation and leaf area index during panicle initiation and grain ripening, and contributed to enhanced nitrogen uptake and nitrogen utilization in YY1540. On average, nitrogen uptake and utilization in YY1540 were highest in T4, but no significant differences among treatments were observed in TYHZ. Dry matter accumulation and nitrogen uptake from panicle initiation to heading of YY1540 were correlated with number of spikelets per panicle, but no significant correlations were observed for TYHZ. Supplementary topdressing with quick-release nitrogen at the panicle initiation stage was required to increase yield of indica–japonica hybrid rice, whereas single-dose deep fertilization with controlled-release nitrogen is satisfactory for the indica hybrid cultivar.

Side Deep Fertilizing of Machine-Transplanted Rice to Guarantee Rice Yield in Conservation Tillage

“…However, the results of Wang et al [27] concern long-term (14 years) tillage effects on soil and rice. Long-term NT or RT could increase soil compactness, restrict air from entering deep soil, accumulate reducing substances in deep soil, and limit the growth of rice roots [28]. Das et al [11] reported that short-term (4 years) NT increased soil organic carbon, microbial biological carbon, and dehydrogenase activity, and provided superior conditions for root growth.…”

Reasonable Nitrogen Regime in the Main Crop Increased Grain Yields in Both Main and Ratoon Rice

“…Previous studies reported that appropriately increasing the panicle N application rate reduced the number of ineffective tillers and increased the percentage of productive tillers, leading to an increase in the dry matter weight per stem [32][33][34]. The canopy transmittance and root activity were improved by applying more N in the late stage of rice [17,35].…”

Development status and trends in side-deep fertilization of rice

“…If fast-acting fertilizer is used for side-deep fertilization, the nitrogen concentration in the soil layer will be reduced 30 days after rice transplanting, avoiding lodging caused by overgrowth, fully reducing ineffective rice tillers, and promoting early rice development (Zhu et al ., 2019 b ). If side-deep fertilization is done with a controlled-release fertilizer, nutrients can be released slowly over the entire growth period, and can release nutrients at a suitable rate for the rice plant's requirements (Xiao-Dan et al ., 2021). But there are also studies that point out (Lyu et al ., 2021), since a controlled-release fertilizer has a slow release of nutrients in the early stage of rice growth, it is not conducive to rice tillering.…”

“…Therefore, the fertilizer requires a stable composition, good surface compression resistance, uniform particle size distribution and stable water absorption characteristics (Massoudi, 2001;Linquist et al, 2012). Wang et al (2020) analyzed more than ten mainstream granular fertilizers, including slow-and controlled-release fertilizers, special rice fertilizers, compound fertilizers, blended fertilizers and controlled-release urea, and finding that their average particle size was 3-4 mm. The fertilizer with the best stability was 'Heart to Heart' controlled-release urea, which basically does not absorb water.…”

“…According to recent research, the fertilization mode should be determined according to the rice season and variety type (Wang et al, 2020). For double-cropping rice or single-cropping conventional rice with a short growth period, the yield difference between single and multiple fertilization is not obvious, and onetime side-deep fertilization can be used.…”