生物炭对干旱胁迫下咖啡苗生长及非结构性碳水化合物的影响

为明确在干旱胁迫下施用生物炭对咖啡苗生长及非结构性碳水化合物（NSC）含量的影响，以正常水分处理（W1：土壤水分为最大持水量的65%~70%，不施用生物炭；W2：土壤水分为最大持水量的65%~70%，施用相当于烘干土质量5%的生物炭）为对照，设置不同生物炭处理（D1：不施生物炭；D2：施用量为干土质量的5%）下进行持续干旱与复水的盆栽试验，干旱与复水共设4个处理，分别为持续干旱9 d（DL）、持续干旱13 d（DS）、持续干旱9 d+复水后3 d（DL+R）、持续干旱13 d+复水后3 d（DS+R），分析各器官（根、茎、叶）干物质量、NSC组分含量及其质量的变化。结果表明：与正常水分处理（W1）相比，持续干旱9 d时（DL），D1处理咖啡苗叶的可溶性糖含量、淀粉含量和NSC比率分别下降22.5%、21.1%和21.1%，根的可溶性糖含量和NSC比率分别显著提高8.7%和62.8%，茎的可溶性糖含量和NSC比率分别显著提高22.0%和28.2%。持续干旱13 d时（DS），D1处理较W1处理的根、茎、叶干质量和总干物质量分别下降30.6%、22.2%、34.8%和30.8%，叶的NSC含量和NSC比率分别下降23.7%和16.4%，根的NSC含量和NSC比率分别增加33.8%和57.9%；生物炭处理（D2）较不施生物炭的处理（D1）总干质量增加16.7%，根的NSC含量和茎的NSC比率分别下降18.0%和24.1%，叶的NSC含量和NSC比率分别增加22.8%和15.0%。持续干旱9 d复水后3 d时（DL+R），生物炭处理（D2）对各器官NSC含量恢复作用显著，且与正常水分处理（W1）间无显著差异；干旱13 d复水后3 d时（DS+R），不施生物炭处理（D1）的咖啡苗生长未恢复，而生物炭处理（D2）对咖啡苗恢复作用显著，D2较D1处理的总干质量增加20.3%，叶的NSC含量增加22.7%，根和茎的NSC含量分别下降11.8%和15.3%。可见，施用生物炭是增强咖啡抗旱性和减缓咖啡NSC组分剧烈变化的有效途径。

Effects of biochar on growth and non|structural carbohydrates of coffee seedlings under drought stress

The purpose of this study was to clarify the effects of biochar applicationon the growth of coffee seedlings and non|structural carbohydrates (NSC) under drought stress. The normal water treatment was as control (W1: 65%~70% soil moisture of the maximum water holding capacity with no biochar applied; W2: 65%~70% soil moisture of the maximum water holding capacity with 5% biochar applied to dry soil). The pot experiment of continuous drought and rewatering under different biochar treatments was set up as D2 of 5% of soil dry weight and D1 of no biochar applied under the same drought stress.Four treatments were set up for drought and rewatering, which were continuous drought for 9 days (DL), continuous drought for 13 days (DS), continuous drought for 9 days and rewatering for 3 days (DL + R), and continuous drought for 13 days and rewatering for 3 days (DS+R). The changes of dry mass, NSC component content and quality of each organ (root, stem and leaf) were analyzed. The results showed that after 9 days of continuous drought (DL), compared with normal water treatment (W1), the soluble sugar content, starch content and NSC ratio of coffee seedling leaves in D1 treatment decreased by 22.5%, 21.1% and 21.1%, respectively. The soluble sugar content and NSC ratio of roots were significantly increased by 8.7% and 62.8%, and the soluble sugar content and NSC ratio of stems were significantly increased by 22.0% and 28.2%，respectively. At 13 days of continuous drought (DS), compared with normal water treatment (W1), the dry mass of roots, stems, leaves and total dry mass of D1 treatment decreased by 30.6%, 22.2%, 34.8% and 30.8%, respectively; the NSC content and NSC ratio of leaves decreased by 23.7% and 16.4%, respectively; and the NSC content and NSC ratio of roots increased by 33.8% and 57.9%, respectively. Meanwhile, compared with the treatment without biochar (D1), the total dry mass of biochar treatment (D2) increased by 16.7%, NSC content in roots and NSC ratio in stems decreased by 18.0% and 24.1%, and NSC content and NSC ratio in leaves increased by 22.8% and 15.0%. After 9 days of continuous drought and 3 days of rewatering (DL+R), biochar treatment (D2) significantly restored the NSC content of each organ, and there was no difference between biochar treatment and normal water treatment (W1); and rewatering 3 days after 13 days of drought (DS+R), coffee seedlings without biochar treatment (D1) did not recover, while biochar treatment (D2) had a significant recovery effect on coffee seedlings, compared with D1 treatment. The total dry mass of D2 increased by 20.3%, the NSC content of leaves increased by 22.7%, and the NSC content of roots and stems decreased by 11.8% and 15.3%. The findings indicated that the application of biochar to soil was an effective way to enhance the drought resistance of coffee and to slow down the drastic changes of NSC components in coffee.