灌溉量和施氮量对油用亚麻茎秆抗倒性能及产量的影响

为明确灌水和施氮对油用亚麻(Linum usitatissimum L.)抗倒伏能力和产量的影响,以‘陇亚杂1号’为材料,于2012—2013年以灌溉量为主处理(W1:2 700 m3·hm-2;W2:3 300 m3·hm-2),施氮量为副处理纯氮量分别为N0:0 kg·hm-2(CK);N1:37.5 kg·hm-2(低氮);N2:112.5 kg·hm-2(中氮);N3:225 kg·hm-2(高氮)],研究灌溉量和施氮量对与油用亚麻抗倒性能相关的形态学特性、茎秆强度、抗倒伏指数及茎秆化学组分含量、产量构成因子及产量的影响。结果表明,随灌溉量的增加,茎秆强度和抗倒伏指数下降,株高增加,重心上移,茎粗、茎壁厚度降低,地上部干重增加,根干重减少,根冠比下降,同时茎秆中纤维素、木质素、可溶性糖和淀粉的含量下降;随施氮量的增加,茎秆强度和抗倒伏指数先升高后降低,株高和重心高度增加,茎粗、茎壁厚度、根干重和根冠比先增后减,地上部干重增加,茎秆中各化学组分含量及产量也先增加后降低。进一步分析发现抗倒伏指数与茎秆强度、茎粗、茎壁厚度、根干重、根冠比、纤维素含量、木质素含量、可溶性糖含量及淀粉含量均呈正相关关系,与株高、重心高度、地上部干重呈负相关关系。低灌水处理(W1)的茎秆强度、抗倒伏指数和产量分别比高灌水处理(W2)高30.55%、41.06%和0.53%,过多灌水不利于油用亚麻茎秆抗倒伏性能和产量的提高;中氮处理(N2)的茎秆强度分别比不施氮(CK)和高氮(N3)处理高36.8%和3.95%,产量分别高15.9%和0.8%,可见油用亚麻的栽培中施氮量不能过高或过低。因此,生产上采用适宜的灌溉量和施氮量是防止油用亚麻倒伏、获得高产、提高生产效益的重要措施。在本试验区,同等肥力土壤条件下,以灌溉量2 700 m3·hm-2和纯施氮量112.5 kg·hm-2为宜。

Effects of irrigation and nitrogen fertilizer rates on oilseed flax stem lodging resistance and yield

Although market demands for oilseed flax (Linum usitatissimum L.) gradually expanded in recent years, low yields restricted the development of oilseed flax. Lodging is a common problem in oilseed flax production which causes yield loss and quality deterioration. Effective water and fertilizer management is an important measure for improving oilseed flax yields. In order to investigate the effects of irrigation and nitrogen fertilizer application on lodging resistance and yield of oilseed flax, a field experiment was conducted in 2012-2013 with hybrid variety of "Longyaza1" oilseed flax in Yuzhong County, Gansu Province. In the experiment, the main plots were irrigated at 2 700 m³·hm^-2 (W₁) and 3 300 m³·hm^-2 (W₂), while the subplots were fertilized with nitrogen (N) at 0 kg·hm^-2 (N₀ or CK), 37.5 kg·hm ^-2 (N₁), 112.5 kg·hm^-2 (N₂) and 225 kg·hm^-2 (N₃). Water meter was used to strictly control irrigation amount, urea was used as N fertilizer, two-thirds as base fertilizer and one-third as top-dresser before budding stage. Then the effects of irrigation and nitrogen fertilization rates on lodging resistance traits (i.e., lodging resistance index, stem strength, stem chemicals contents) and yield of oilseed flax were determined. The results showed that with increasing irrigation, stem strength and lodging resistance index of oilseed flax declined. Then the plant height and gravity center height increased while stem diameter and culm wall thickness decreased. Also while above-ground dry weight increased, below-ground dry weight and the root-shoot ratio decreased with increasing irrigation. The contents of cellulose, lignin, soluble sugars and starch of oilseed flax stem decreased. Also with increasing nitrogen input, oil flax stem strength and lodging resistance index initially increased and then decreased. The height and gravity center height of the plant increased while stem diameter, culm wall thickness, root dry weight and root-shoot ratio initially increased and later decreased. Furthermore, above-ground dry weight increased and stem contents of various biochemical components and yield initially increased and then decreased. Further analysis showed that lodging resistance index of oilseed flax was positively correlated with stem strength, stem diameter, culm wall thickness, root dry weight, root-shoot ratio and then cellulose, lignin, soluble sugar and starch contents. Lodging resistance index of oilseed flax was also negatively correlated with plant height, gravity center height and above-ground dry weight. Compared with high irrigation, low irrigation increased stem strength, lodging resistance index and yield respectively by 30.55%, 41.06% and 0.53%. Thus excessive irrigation was did not enhance lodging resistance of oilseed flax. The highest stem strength and yield occurred under N₂ treatment. Compared with CK, N₂ treatment increased stem strength and yield respectively by 36.8% and 15.9%. Compared to high nitrogen treatment (N₃), N₂ treatment increased stem strength and yield respectively by 3.95% and 0.8%. Thus, neither too high nor too low nitrogen fertilization was necessary in oilseed flax cultivation. The appropriate amounts of irrigation and nitrogen fertilizer was very important for preventing lodging, ensuring high production and increasing productivity of oilseed flax. Under the experimental condition in this study, W1N2 treatment (of 2 700 m³·hm^-2 irrigation and 112.5 kg·hm^-2 pure N) was the proper combination of irrigation and nitrogen fertilizer for high oilseed flax yield.