Effects of plant density and nitrogen splitting on grain yield and nitrogen uptake in rice re-cropping

Abstract

Rice (Oryza sativa L.) re-cropping has a special place in the crop rotation of rice plants in terms of increasing the efficiency of land productivity. A two-year research (2013–2014) was done with three replications to determine the best planting density and appropriate nitrogen splitting in rice re-cropping at Qaemshahr Agricultural Faculty, Mazandaran, northern Iran. For this purpose, a split plot design in RCBD format was used. Experimental factors consisted of plant density (33.3, 25, and 16 plants per sq m at intervals of 30 × 10, 20 × 20, and 25 × 25 cm², respectively) as the main factor, and nitrogen splitting (NS1: all as a base, NS2: $\frac{1}{2}$ base + $\frac{1}{2}$ tillering, NS3: $\frac{1}{2}$ base + $\frac{1}{2}$ panicle formation, NS4: $\frac{1}{3}$ base + $\frac{1}{3}$ tillering + $\frac{1}{3}$ panicle formation, and NS5: $\frac{1}{3}$ base + $\frac{1}{3}$ panicle formation + $\frac{1}{3}$ end of panicle emergence) as subfactors. The results showed that the grain yield was higher for 2014 than in 2013 by 60.0%, due to increasing the number of panicles per sq m (27.2%) and the weight of 1000 grains (7.2%). The maximum grain yield was achieved at a density of 33.3 plants per sq m along with NS4 treatment. The highest straw nitrogen uptake was observed in 2013 by NS4 treatment. The maximum grain nitrogen concentration, nitrogen harvest index, and grain protein yield were recorded in 2014 along with NS4 treatment. The density of 33.3 plants per sq m and NS of $\frac{1}{3}$ base + $\frac{1}{3}$ tillering + $\frac{1}{3}$ panicle formation are suggested for rice re-cropping.

Keywords:

• Fertilizer splitting
• N harvest index
• paddy yield
• planting spaces
• second crop of rice

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 BBCH-Code 21: first tiller detectable.

2 BBCH-Code 32: panicle 1–2 mm in length.

3 BBCH-Code 59: neck node level with the flag leaf auricle, anthers not yet visible.