Abstract
To determine the soil mechanism in root-zone caused by water saving and the production response to alternate drip irrigation (ADI), the present study investigated the effects of deficit ADI on tomato growth using the conventional surface drip irrigation (CDI) as a control. The interactions among the experimental treatments on root index, photosynthetic efficiency, biomass accumulation, yield, fruit quality and irrigation water use efficiency (IWUE) were assessed and the inner mechanism of root-soil effecting on tomato growth, photosynthate distribution, yield and quality was discussed. ADI significantly enhanced root-soil interaction, promoted soil nitrogen and phosphorus absorption by tomato and tomato growth. However, different soil moisture deficits significantly affected tomato photosynthate accumulation and distribution, as well as fruit quality. With irrigation amount of 50% field capacity (F), ADI significantly increased soluble sugar, total soluble solid and lycopene by 38.08%, 19.48% and 30.05%, respectively, compared to those of CDI, but decreased irrigation amounts by 29.86% in comparison with the CDI one. ADI of 70% F could significantly distribute more photosynthate to fruits, thus enhanced tomato yields by 24.6% and improved IWUE by 17.05% compared to that of CDI. In addition, ADI of 70% F improved tomato fruits quality, and in particular organic acid was decreased by 43.75% and sugar-acid ratio was increased by 97% compared to CDI. However, ADI of 60% F distributed more photosynthate to plant, showing no significant difference of yields in comparison with CDI and ADI of 70% F, but a higher IWUE by 19.54% than that of CDI. ADI of 60% F significantly enhanced soluble sugar, total soluble solid, soluble protein, lycopene and sugar-acid ratio in tomato fruits by 2.06, 1.26, 1.61, 1.4 and 3.2 times respectively compared to CDI. Therefore, ADI of 60% or 70% F can be overall recommended for tomato production in a greenhouse, plant growth, fruit yield and quality, and IWUE.
Highlights
Tomato (Solanum lycopersicum) is one of the most popular vegetable loved by people and has the largest cultivating area in the word [1]
Compared with conventional surface drip irrigation (CDI), alternate drip irrigation (ADI) failed to improve chlorophyll a and chlorophyll b content; chlorophyll a/b values in FP1 under ADI of 60% and 70% field capacity were significantly enhanced compared to CDI
The results revealed that ADI with soil moisture deficit (60% field capacity) was best beneficial to significantly improve tomato quality moderate soil moisture deficit (60% field capacity) was best beneficial to significantly improve tomato index, and ADI with the larger or light soil moisture deficit (50% or 70% field capacity) was the second quality index, and ADI with the larger or light soil moisture deficit (50% or 70% field capacity) was beneficial to tomato fruit quality
Summary
Tomato (Solanum lycopersicum) is one of the most popular vegetable loved by people and has the largest cultivating area in the word [1]. Tomato planting acreage and production have been still expanding year by year with the increasing demand from consumers [2]. Tomato needs plenty of water to grow [3], water scarcity is the major limiting factor to its growing, especially in arid and semi-arid areas. Drip irrigation (DI) is reportedly an effective and efficient solution for the contradiction between water demand and water scarcity of agricultural production in arid and semi-arid areas [1]. The effects of different DI methods, irrigation amounts, and water-fertilizer coupling or integration on tomato growth, IWUE, yield and fruit quality have been extensively. Public Health 2020, 17, 781; doi:10.3390/ijerph17030781 www.mdpi.com/journal/ijerph
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