间作对马铃薯根系及坡耕地红壤结构稳定性的影响

Effects of Intercropping on the Potato Roots and Soil Structure Stability in Slopping Land of Red Soil Region

为了揭示间作对马铃薯根系和坡耕地红壤结构稳定性的影响,田间试验采用随机区组设计,设置马铃薯单作、玉米马铃薯间作2个处理,测定马铃薯各生育阶段的土壤团聚体稳定性指标、根系形态特征及其分泌物含量,分析了不同种植模式下马铃薯的根系形态及其分泌物对土壤团聚体稳定性的影响。结果表明:(1)在同一种植模式下,除根平均直径外的马铃薯根系形态特征指标均随生育期的推移呈先增加后降低的趋势。在马铃薯的开花期和块茎膨大期,间作马铃薯根系总根长、总根表面积和总根体积与单作相比均较高,且在块茎膨大期间作马铃薯根系总根长、总根表面积和总根体积相对于单作分别显著增加了24.41%,24.75%,35.03%(p<0.05)。(2)马铃薯根系分泌物总糖和总有机酸含量随生育期推移的变化趋势与形态指标变化相同,呈先增加后降低趋势。马铃薯块茎膨大期的根系分泌物总糖、总有机酸含量与单作相比分别显著增加了37.85%,34.64%(p<0.05)。(3)在单间作种植模式下,土壤团聚体稳定性指标R0.25,MWD和GMD均随生育期的推移呈增加趋势(p>0.05),D呈显著下降趋势(p<0.05)。除开花期的MWD外间作模式下的R0.25,MWD和GMD均显著高于单作(p<0.05),D呈降低趋势,且间作显著低于单作(p<0.05)。(4)在开花期和块茎膨大期,马铃薯根系总根长、总根表面积、总根体积、分泌物总糖和总有机酸与土壤团聚体稳定性指标R0.25,MWD,GMD均呈正相关,与D呈负相关,其中块茎膨大期大部分指标间的相关性达到显著(p<0.05)或极显著(p<0.01)水平。在成熟期时,马铃薯根系分泌物与土壤团聚体稳定性指标所呈相关关系与前两个时期相同,而根系形态特征与土壤团聚体稳定性指标所呈相关关系与前两个时期相反。综上,间作条件下马铃薯改善土壤结构稳定性的效果优于单作马铃薯。

In order to reveal the effect of intercropping on potato roots and structural stability of red soil in sloping farmland, the randomized block design was used in the field experiment, two treatments of potato monoculture and maize-potato intercropping were set to determine the soil aggregate stability index, root morphological characteristics and exudate contents at different growth stages of potato, and the effects of root morphology and exudates of potato on soil aggregate stability under different planting patterns were analyzed. The result showed that:(1) under the same planting pattern, the root morphological characteristics of potato system except root average diameter increased first and then decreased with the growth period;in potato flowering and tuber bulking period, the total root length, total root surface area and total root volume of intercropping potato were higher than those of monoculture, and the total root length, total root surface area and total root volume of intercropping potato during tuber bulking increased by 24.41%, 24.75% and 35.03%(p<0.05), respectively, compared with those of monoculture;(2) the variation trend of total sugar and total organic acid content in root exudates of potato with the growth period was the same as that of morphological indexes, which increased first and then decreased;the contents of total sugar and total organic acid in root exudates of potato tuber bulking stage significantly increased by 37.85% and 34.64%(p<0.05) compared with those of monoculture;(3) soil aggregate stability index R0.25, MWD and GMD showed an increasing trend with the passage of growth period under the monoculture and intercropping planting mode(p>0.05), and D showed a significant downward trend(p<0.05). R0.25, MWD and GMD under intercropping mode were significantly higher than those under monoculture except for MWD at flowering period(p<0.05);D showed a decreasing trend, and intercropping was significantly lower than monoculture(p<0.05);(4) at flowering period and tuber bulking period, the total root length, total root surface area, total root volume, total sugar in exudates and total organic acid of potato roots were positively correlated with soil aggregate stability indexes R0.25, MWD and GMD, and negatively correlated with D;the correlation among most indexes at tuber bulking period reached the significant(p<0.05) or extremely significant(p<0.01) level;at maturity period, the correlation between potato root exudates and soil aggregate stability index was the same as those in the previous two periods, while the correlation between root morphological characteristics and soil aggregate stability index was opposite to those in the previous two periods. To sum up, the effect of intercropping potato on improving soil structure stability is better than monoculture potato.