Abstract:

【Objective】 The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation. 【Method】 Based on the field experiments, three treatments of soil water content were conducted with 90%θf, 75%θf, 60%θf (θf is field water capacity). Cotton roots and root-shoot ratio were studied with digging method, and the soil moisture was observed with TDR, and cotton yield was measured. 【Result】 The results indicated that the growth of cotton root accorded with Logistic growth curve in corresponding three treatments of soil water content, the cotton root grew quickly and its weight was very high under the soil water treatment of 75%θf because of the suitable soil water condition, grew slowly and its weight was lower in the soil of the treatment of 90%θf beyond the suitable soil water condition, and the root weight was mediate under the soil water treatment of 60%θf. For the three water treatments, the cotton root weight decreased with soil depth, and decreased extensively in deeper soil layer with the soil moisture increment. Compared with other treatments, the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under the soil water treatment of 75%θf. The cotton root system was distributed mainly in the soil narrow row and wide row mulched with plastic film, and the distribution of root was small in the soil outside plastic film. Compared with other treatments, the weight of cotton root was the highest in the soil narrow row or wide row mulched with plastic film under the soil water treatment of 75%θf. Root-shoot ratio decreased with the soil moisture increment. The soil water content affected cotton yields, and cotton yield was the highest under the soil water treatment of 75%θf. 【Conclusion】The sustained higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.

Key words: mulched drip irrigation, cotton (Gossypium hirsutum L.), soil water content, root