Abstract:
【Objective】 To study the effects of nitrogen forms and variety on root morphology and nitrogen accumulation of cotton, and explore the interaction mechanism between variety and nitrogen forms in the hope of providing a theoretical basis for the rational selection of nitrogen fertilizer form and variety in cotton.
【Methods】 The experiment was conducted in the incubation room of the Agricultural Science Building of Xinjiang Agricultural University in 2020. Two varieties (Xinluzao 45 and Xinluzao 48 ) and four fertilization treatments ( no nitrogen fertilizer (CK), urea (N
1 ), ammonium sulfate (N
2), and calcium nitrate (N
3) ) were set in the completely randomized root-box culture experiment. The nitrogen fertilizer application rate was 300 kg/hm
2. Samples were collected 90 days after sowing to determine the root morphological parameters and nitrogen accumulation.
【Results】 The order of cotton root morphology and nitrogen accumulation was N
3 > N
1 > N
2 > CK. The root morphology parameters (total root length, dry matter weight (
P<0.05), surface area, volume), root, stem, leaf (
P<0.05) and plant nitrogen accumulation of N
3 treatment were significantly higher than those of N
2 and CK treatment (
P<0.01), which increased by 24.66%, 33.93%, 19.61%, 18.57% and 52.64%, 50.95%, 16.20%, 28.09%, respectively. Compared with CK treatment, the average increase was 40.57%, 61.09%, 38.65%, 33.31% and 103.02%, 119.59%, 57.40%, 76.12%, respectively, and there was no significant difference between processing ways of N
1 and N
3. There were no remarkable differences between interactive function of root forms and nitrogen accumulation which are acted by cotton variety and nitrogen form. The total root length and root volume of Xinluzao 48 were significantly higher than those of Xinluzao 45 (
P<0.01), with an average increase of 9.16% and 7.01%, respectively. The nitrogen accumulation in roots, stems (
P<0.05), leaves and plants was also significantly higher than that of Xinluzao 45 (
P<0.01), with an average increase of 15.28%, 7.75%, 9.55% and 9.86%, respectively. Xinluzao 45 root-shoot ratio of CK treatment and specific root length of N
2 treatment, was significantly lower than other treatments, Xinluzao 48 root-shoot ratio and specific root length were not significantly different between the treatments.
【Conclusion】 Nitrate nitrogen fertilizer is more conducive to cotton root morphological development and nitrogen accumulation than urea and ammonium nitrogen fertilizer. The total root length, root volume and plant nitrogen accumulation of Xinluzao 48 are significantly higher than those of Xinluzao 45, and there is no significant difference in root-shoot ratio and specific root length among different treatments, indicating that the variety had obvious advantages.