Impacts of nitrogen and zeolite managements on yield and physicochemical properties of rice grain

Zeolite (Z) can hold soil water and nutrient to obtain a higher yield on introduction into moist soil. However, the effects of Z and nitrogen (N) managements on rice grain quality is unclear. Therefore, the effects of different amounts of Z (Z^sub 0^: 0 t/hm^sup 2^; Z^sub 0.9^ and Z^sub 0.22^: 10 t/hm^sup 2^ in different particle sizes of 0.45-0.9 mm and 0.17-0.22 mm in diameter) and N (N^sub 0^, N^sub 52.5^, N^sub 105^, N^sub 157.5^: 0 kg/hm^sup 2^, 52.5 kg/hm^sup 2^, 105 kg/hm^sup 2^, 157.5 kg/hm^sup 2^), and Z (Z^sub 0^, Z^sub 10^: 0 t/hm^sup 2^, 10 t/hm^sup 2^) and application frequencies of N on rice yield and grain quality were investigated in 2014 and 2015 in Northeast coastal region of China where Z^sub 10^ was extended to use in large areas. Results showed that both N and Z applications significantly increased the yields of rough rice (RRY), brown rice, milled rice and head rice. However, there was no significant difference between Z^sub 09^ and Z^sub 0.22^. The chalkiness area, length-width ratio and head rice rate were not influenced by Z and N applications. However, Z application significantly decreased the chalk rate and slightly increased amylose content (AC) but mattered little to taste value (TV) of rice and rice cooking quality. N could significantly increase rice protein content (PC) but lessen the TV and breakdown value; the order of influence degree on rice yield increasing was as follows: CRF2 (third-split fertilization with Z^sub 10^), CRF1 (basal fertilization one time with Z^sub 10^), U2 (urea: third-split fertilization without Z) and U1 (basal fertilization one time without Z). Both CRF1 and CRF2 greatly enhanced the RRY. However, CRF1 was recommended for clear decrease in labor and fuel for growers. Compared with treatments of U1 and CRF1, CRF2 and U2 significantly decreased the AC. PC exhibited significant negative relation to TV and greatly determined the rice eating quality and cooking quality.