Abstract:
The dynamics of soil chemical properties and enzyme activities at different growth stages as well as their relationships with sesame yield were examined with 10 sesame varieties (C1-C10). The results showed that with the development of sesame, soil pH, the contents of available phosphorus (AP) and available zinc (AZn), and the activities of cellulose and urease increased by 4.1%, 19.4%, 15.4%, 11.1% and 21.4% at the flowering stage, and increased by 3.3%, 12.9%, 13.0%, 70.4% and 11.3% at the maturity, compared with seedling stage, respectively. The contents of organic matter, total nitrogen (TN), available nitrogen (AN) and protease activity decreased by 8.2%, 1.7%, 30.3% and 17.1% at the flowering stage, and 9.0%, 5.8%, 33.2% and 30.3% at the maturity, respectively. Available potassium (AK) content and acid phosphatase activity initially increased by 23.3% and 10.7% prior to the flowering stage and then decreased by 20.6% and 3.5% till the maturity, respectively. Available boron (AB) content and sucrase activity showed a "V" type change. The AB content decreased by 41.4% at the flowering stage but increased by 7.3% till maturity; while sucrose activity had a 25.8% of decrease at the flowering stage, and no difference till maturity compared with the seedling stage. There was no difference in β-glucosidase activity between the seedling and flowering stage, but the activity decreased by 33.5% till maturity. In addition, the contents of AZn, AK, AB, AN and AP, as well as the activities of cellulase and sucrase varied among genotypes and growth stages; while soil pH, TN and organic matter contents, and the activities of β-glucoside, protease, acid phosphatase and urease were relatively stable. Among these fertility factors, soil available nitrogen content and protease activity at the seedling stage, soil available boron content and cellulase activity at the flowering stage, and soil pH value at maturity were positively correlated with yield. Therefore, the strategies to increase sesame yield in the red soil include increasing input of basal nitrogen fertilizer before seeding, spraying borax fertilizer at the flowering stage, and applying alkaline substances such as lime or other measures to increase pH or prevent further acidification of the red soil.