不同滴灌水肥配施模式对土壤硝态氮与棉花根系形态的影响

为探明不同滴灌水肥配施模式对土壤硝态氮与棉花根系形态的影响,在N-W-N(前期滴入氮肥、中间滴清水、后期再滴入氮肥)的常规水肥配施模式基础上,通过设置4种不同的施肥时段W1(1/3,1/3,1/3)(在一次施肥的两端时间滴肥,中间1/3时间段仅灌清水)、W2(1/2,1/4,1/4)(在一次施肥的前1/2和后1/4时间段滴肥,中间1/4时间段仅灌清水)、W3(1/4,1/4,1/2)(在一次施肥的前1/4和后1/2时间段滴肥,中间1/4时间段仅灌清水)和W4(1/4,1/2,1/4)(在一次施肥的前1/4和后1/2时间段滴肥,中间1/4时间段仅灌清水)],探究其对0～20、20～40和40～60 cm土壤硝态氮累积规律及棉花根系形态指标的影响。结果表明:滴灌棉田不同生育时期各土层硝态氮质量分数表现为60 cm20 cm40 cm,棉花根系各形态指标的生长表现为40 cm60 cm20 cm;在不同水肥配施模式下,各土层硝态氮质量分数表现为W4W3W2W1,根系各形态指标的生长表现W1W2 W3 W4;通过不同滴灌水肥配施模式与根系形态指标相关分析结果表明,各处理对总根长、总根表面积、总根体积、根尖数均有显著影响,其中W1模式效果最佳。表明合理的水肥配施模式对滴灌棉花根系生长有促进作用,从而协同增加地上部分干物质积累,促进棉花高产。

Effects of Different Drip Fertigation Modes on Soil Nitrate Nitrogen and Cotton Root Morphology

Drip fertigation mode is the key yield improvement technologies in crop production systems. In this study,a field experiment was conducted to investigate the effects of four drip fertigation modes,W1(time drip fertigation at both ends of one fertilization and only clear water in the middle of one third time),W2(time drip fertigation in the first 1/2 and the last 1/4 period and only clear water in the middle 1/4 period),W3(time drip fertigation in the first 1/4 and the last 1/2 period and only clear water in the middle 1/4 period),and W4(time drip fertigation in the first 1/4 and the last 1/4 period and only clear water in the middle 1/2 period) on the accumulation rules of nitrate nitrogen and cotton root morphological index in the soil depth of 0-20 cm,20-40 cm and 40-60 cm on the basis of conventional N-W-N fertigation modes(early drip of nitrogen fertilizer,intermediate drip of clear water and later drip of nitrogen fertilizer). The results showed that nitrate nitrogen mass fraction in different depth decreased in the order 60 cm>20 cm>40 cm at all growth stages,while the cotton root morphological index decreased in the different order 40 cm>60 cm>20 cm. Nitrate nitrogen content in different depth decreased in the order W4>W3>W2>W1 under different fertilization patterns,while the root morphological index decreased in the opposite order W1>W2>W3>W4. The correlation analysis between different drip fertigation modes and root morphological index showed that all four modes had significant effects on the total root length,total root surface area,total root volume and root tip number,of which W1 had the most significant effect. These results showed that reasonable fertigation mode could promote the growth of cotton root system leading to synergistically increase the dry matter accumulation of aboveground part and obtain high yield.