营养液浓度对水稻机插水培毯状苗秧苗素质及产量的影响

为探明机插水稻育秧新方法——水培毯状苗育秧方法壮秧培育适宜的营养液浓度,以武运粳24号(常规粳稻)和6两优9368(杂交籼稻)为试验材料,分析不同水培营养液浓度(S1、S2、S4、S8,分别表示营养液浓度为原液浓度的1、2、4、8倍,原液组成为:0.643 g/kg N、0.615 g/kg P2O5、0.359 g/kg K2O、127.2 mg/kg Mg、26.34 mg/kg Fe、8.26mg/kg Mn、0.11 mg/kg Mo、0.66 mg/kg B、0.99 mg/kg Zn、1.405 mg/kg Cu、49 mg/kg SiO2、709.1 mg/kg Ca)对水培毯状苗育秧方法秧苗素质、机插质量、大田群体生长及产量形成的影响。结果表明,移栽前秧苗地上部干物质积累量、苗基宽、发根力、叶片和根系氮含量、叶面积指数、光合速率总体上均随着营养液浓度的增加呈增加趋势;然而,高营养液浓度处理时秧苗根系生长受到抑制(干物质积累小、根系活性低),叶片和根系丙二醛(malonaldehyde,MDA)含量升高、抗氧化酶活性(超氧化物歧化酶(superoxidedismutase,SOD)、过氧化物酶(peroxidase,POD))下降,成苗率变差,机插空穴率升高。低营养液浓度(S1)处理的秧苗素质弱、机插大田后返青活棵慢、分蘖发生延迟、干物质积累量低、穗数不足而影响产量(武运粳24号为10.74 t/hm~2,6两优9368为10.96 t/hm~2);随着营养液浓度的增加(S2～S4),产量呈增加趋势(S2和S4处理下,武运粳24号产量分别为12.09和11.64 t/hm~2,6两优9368分别为12.16和12.47 t/hm~2);但产量并没有随着营养液浓度的升高而持续增加,S8处理下,武运粳24号产量为11.59t/hm~2,6两优9368产量为11.48 t/hm~2),主要受限于穗数不再增加,且穗粒数有下降趋势。因此,水培毯状苗育秧方法适宜的水培营养液浓度,常规粳稻武运粳24号为S2(2倍于原液浓度),杂交籼稻6两优9368为S2～S4(2～4倍于原液浓度)。

Effects of nutrient solution concentrations on quality and yield of hydroponically grown long-mat rice seedlings under mechanical transplanting

Hydroponically grown long-mat rice seedlings (HLMS) is a novel seedling cultivation method that improves work efficiency with lower labor costs, increases flexibility of seedling age, enables high-yield and high-efficiency rice production. Seedbed nutrient management is very important for the cultivation of vigorous rice seedlings under mechanical transplanting. Thus, it is of great importance for high yield formation to understand rice seedling quality, mechanical transplanting quality, field growth characteristics and yield formation affected by different nutrient solution concentrations. In this paper, field experiment was conducted in 2014 by using two different cultivars japonica rice (Wuyunjing 24) and indica hybrid rice (6 Liangyou 9368) under different nutrient solution concentrations S1, S2, S4 and S8 for HLMS. Those treatments mean 1, 2, 4, 8 times as much as original nutrient solution concentration, respectively, and the composition of original nutrients in the solution were 0.643 g/kg N, 0.615 g/kg P2O5, 0.359 g/kg K2O, 127.2 mg/kg Mg, 26.34 mg/kg Fe, 8.26 mg/kg Mn, 0.11 mg/kg Mo, 0.66 mg/kg B, 0.99 mg/kg Zn, 1.405 mg/kg Cu, 49 mg/kg SiO2, 709.1 mg/kg Ca. The results showed that there were increases in shoot dry biomass, seedling base stem diameter, root-developing ability, plant nitrogen content, leaf area index and photosynthetic rate along with the increase of nutrient solution concentrations for both cultivars before transplantation. However, under the high nutrient solution concentration (S8), the root growth (dry matter accumulation, root activity) was inhibited, seedling emergence rate and antioxidant enzymes activities (superoxide dismutase (SOD), peroxidase (POD)), malonaldehyde (MDA) contents in leaves and roots were decreased. Further, the missing hill rate was increased along with the increase of nutrient solution concentrations in both Wuyunjing 24 and 6 Liangyou 9368 cultivars, and it was significantly higher in S8 than that of S1, S2 and S4. The floating seedling rate was increased firstly and then decreased with the increase of nutrient solution concentrations. The differences of seedlings per hill among all treatments were not obvious for Wuyunjing 24, but the seedlings per hill of S1, S2, S4 treatments were respectively significantly higher than that of S8(P?0.05) for 6 Liangyou 9368. There was no significant difference in dry matter accumulation among treatments S2, S4 and S8 at maturity stage of Wuyunjing 24.; but for 6 Liangyou 9368, the dry matter accumulation at maturity of treatment S2 and S4 were significantly higher than that of treatment S1 and S8 , respectively. The period dry matter accumulation ratio from heading to maturity stage was increased firstly and then decreased with the increase of nutrient solution concentrations. The reduction of grain yield under treatment S1 (10.74 t/hm2 for Wuyunjing 24 and 10.96 t/hm2 for 6 Liangyou 9368) resulted from weaker seedling quality, slower seedling reviving in the paddy field, delayed tiller emergence, lower dry matter accumulation in the paddy field and less panicles. Under the treatment S2 and S4, the grain yield of Wuyunjing 24 was 12.09 and 11.64 t/hm2 respectively, and 6 Liangyou 9368 were 12.16 and 12.47 t/hm2. The grain yield increased with the increase of nutrient solution concentrations when the concentration of nutrient solution was equal or less than 4 times of the original solution. However, the grain yield did not continue to increase with the increase of nutrient solution concentration due to the non-increased panicles and the decreased spikelets number per panicle. The grain yield of Wuyunjing 24 and 6 Liangyou 9368 were 11.59 and 11.48 t/hm2 under S8 treatment). Therefore, the suitable nutrient solution concentration of HLMS was S2 for Wuyunjing 24 and S2-S4 for 6 Liangyou 9368.