Abstract:

【Objective】The objective of this paper was to explore the reasons of the delayed bud burst and to improve the growth of grapevine in saline land in spring.【Method】Three year old ‘Summer Black’ grape was used as test material, which was cultivated in Guangbei #2 field with saline land (1.5 m within rows and 3 m between rows, vertical shoot-positioning system, hedgerows, single stem and arm tree shape). Grapes were unearthed in March 2018, ‘tent’ was built after irrigating for the accelerating germination, namely, pulling a wire at a height of 50 cm, with it as the vertex, white plastic film with a width of 80 cm was superimposed on both sides with binding wire. The two sides were opened to the ground with an angle about 45 ^o, then soil was used to cover the edge, a small hermetically sealed triangle known as the ‘tent’ mulching. Two rows were laid for each treatment, plants without covering the ‘tent’ were used as control, and effects of ‘tent’ mulching on soil temperature and grape growth was studied.【Result】‘Tent’ mulching in the Yellow River delta saline land promoted the growth and development of grape and effectively increased the ground temperature in saline land. The average ground temperature of the 10 cm soil layer in the rhizosphere under ‘tent’ mulching was significantly increased by about 5℃, compared with the control. The ground temperature under ‘tent’ mulching increased earlier and retained longer time than that under the control treatment, which decreased the gap between ground temperature and air temperature. The phenological period of grapes bud burst under ‘tent’ mulching were 10-15 days earlier than that under the control, and the bud burst time was earlier and consistent. ‘Tent’ mulching significantly improved the growth quality of grape shoots, growth of new shoots (length), internode length and width of the third node, which were increased by 34.9%, 23.8% and 20%, respectively, compared with the control. Leaves area and weight under ‘Tent’ mulching were increased by 39.9% and 56.6%, respectively, while leaves thickness under ‘Tent’ mulching was increased but there was no significant difference, compared with the control. ‘Tent’ mulching significantly improved the leaves function of grape, leaves chlorophyll content, net photosynthetic rate (P_n) and maximum photochemical efficiency (F_v/F_m), which were increased by 27.6%, 30% and 6.8%, significantly, compared with the control. The photochemical quenching coefficient (qP) was also significantly increased by 21.9%, which indicated that the open degree of PSII reaction center in geothermal environment was large, the energy used in the photochemical pathway was increased, and photosynthesis was increased. In order to explore the causes of delayed temperature rise in saline land, the pot experiments were conducted under the same climatic conditions in Tai'an. The results showed as follows: the response of saline soil ground temperature to air temperature was significantly delayed about 3 h than that of brown soil. The largest differences about the two soil were salt content, soil conductivity, bulk density and porosity. Field measurements showed that saline soil was less aerated than brown soil. The bulk density of the 0-20 cm soil layer in saline soil was as high as 1.45 g?cm ^-3, which belong to a compaction condition. The bulk density was 11.7% higher than that of brown soil, soil porosity was 13.5% lower than that of brown soil, soil reoxidation reduction potential (Eh) and oxygen diffusion rate (ODR) were 49.9% and 13.8% lower than that of brown soil, respectively.【Conclusion】The ‘tent’ significantly increased the ground temperature of saline-alkali land, reduced the time-space difference of air and ground temperature, effectively improved the bud burst process of grape, advance the phenological period of bud burst, improved the growth quality of new shoots, and promoted the growth and development of grapevine in spring.

Key words: saline-alkali land, grapes, ground temperature, delayed, ‘tent’, mulching