A study was conducted in an environmentally controlled greenhouse to evaluate two green bean cultivars, ‘Bronco’ and ‘Paulista’, under three application volumes of irrigation water based on replacing 100, 80, and 60% of evapotranspiration (ET). The experiment was in a split-plot design with three replications, recording vegetative growth, yield, pod parameters, water use efficiency (WUE), and chemical content of pods. The results showed that there were no differences between 80% ET and 100% ET for most parameters. In addition, 80% of ET increased the pod yield and improved the pod parameters and chemical composition. Therefore, this irrigation treatment can increase green bean productivity and improve pod quality. Reducing water application from 100 to 60% of ET progressively increased WUE. The ‘Bronco’ cultivar had a higher plant height, pod yield, WUE, pod weight, pod diameter, and total fiber amount than ‘Paulista’, while the ‘Paulista’ cultivar was superior in total chlorophyll, number of pods per plant, pod length, P, Ca, Mg, Fe, Cu, protein, vitamin C, titratable acid, and soluble sugar.

Seedling overgrowth always develops in undernourished plants due to biotic or abiotic stresses, which significantly decrease the yield of crops and vegetables. It is known that the plant growth retardants paclobutrazol (PBZ) and chlormequat chloride (CCC) are the most commonly used chemicals in controlling seedling height in plants by regulating the gibberellin (GA) biosynthesis pathway. However, the exact molecular regulation mechanism remains largely unknown. This study performed a comprehensive transcriptome profile to identify significantly differentially expressed genes after adding CCC and PBZ to the water culture seedling raising system for the first time. According to the obviously restrained shoots and roots, the GA biosynthesis genes were significantly decreased, as well as the endogenous GA content being reduced. Intriguingly, the GA signaling pathway genes were affected in opposite ways, increasing in roots but decreasing in shoots, especially regarding the phytochrome interacting factor SlPIF1 and the downstream genes expansins (SlEXPs), which promote cell wall remodeling. Further study found that the most down-regulated genes SlEXPA5 and SlEXPA15 were expressed specifically in shoot tissue, performing the function of repressing elongation, while the up-regulated genes SlEXPB2 and SlEXPB8 were proven to be root-specific expressed genes, which may promote horizontal elongation in roots. This research reported the comprehensive transcriptome profiling of plant growth retardants in controlling seedling overgrowth and restraining GA biosynthesis through the regulation of the GA signaling-related genes SlPIF1 and SlEXPs, with an opposite expression pattern between roots and shoots.

Global warming and waterlogging stress due to climate change are expected to continue influencing agricultural production worldwide. In the field, two or more environmental stresses usually happen simultaneously, inducing more complex responses in plants compared with individual stresses. Our aim was to clarify how the two key factors (temperature and water) interacted and influenced physiological response and plant growth in tomatoes under ambient temperature, moderately elevated temperature, waterlogging stress, and moderately elevated temperature and waterlogging stress. The results showed that leaf photosynthesis was inhibited by waterlogging stress but enhanced by elevated temperature, as shown by both the light- and temperature-response curves. The elevated temperature decreased leaf water-use efficiency, but enhanced plant growth and fresh and dry weights of plants under both normal water supply and waterlogging stress conditions. Elevated temperature generally decreased the anthocyanin and flavonol index in tomato leaves compared with the control temperature, regardless of water status. The increase in the optimal temperature was more pronounced in plants under normal irrigation than under waterlogging stress. Waterlogging stress significantly inhibited the root length, and leaf number and area, while the moderately elevated temperature significantly enhanced the leaf number and area. Overall, the moderately elevated temperature offset the effects of waterlogging stress on tomato plants, as shown by leaf gas exchange, plant size, and dry matter accumulation. Our study will improve the understanding of how tomatoes respond to increasing temperature and excess water.

In a soilless culture (perlite substrate), root restriction cannot only reduce production costs but also improve fruit quality. Therefore, this study used different levels of root restriction [T1: 0.5 L, T2: 4 L, nonrestriction treatment (CK): 35 L] on tomatoes to explore their impact on quality. Results showed that total soluble solids (TSS), glucose, fructose, and sucrose contents were increased, whereas L-tryptophan, L-tyrosine, and titratable acidity were decreased under two restriction treatments. Meanwhile, root restriction also promoted the accumulation of phenylalanine and proline. For lycopene and flavonoid biosynthesis (prunin, naringin, naringenin), the restriction groups were significantly higher than those in the control group. Overall, T1 and T2 treatment had a better effect than CK treatment. This study provided an idea for improving substrate use efficiency and tomato quality.

The closed nutrient solution management method allows for the recycling and utilization of nutrient solutions, improving the efficiency of water and fertilizer utilization. This study was conducted to investigate the effects of changing the frequency of nutrient solution renewal and method of nutrient supply on the microbial communities composition, yield, and quality in closed soilless systems by using high-throughput sequencing technology and combining the physicochemical properties of root exudate solution. The results showed that different nutrient solution management modes had a significant impact on the structure and diversity of root exudate solution microbial communities. The abundance and diversity of microorganisms in inorganic perlites were correlative with EC. The abundance and diversity of bacterial communities in the root exudate solution of open liquid supply (CK) were higher than that of closed liquid supply, while the abundance and diversity of fungal communities in the root exudate solution of closed liquid supply (T1, T2, T3) were higher than that of open liquid supply. As the frequency of nutrient solution interval decreased, the accumulation of salt in root exudate solution and the richness and diversity of the fungal community also decreased, especially increasing the K⁺, Ca²⁺, and Mg²⁺ contents, which were positively correlated with potential beneficial Candidatus_Xiphinematobacter, Arachidicoccus, Cellvibrio, Mucilaginibacter, Taibaiella communities and decreasing the content of soluble protein, Vitamin C content, but not significantly increased cucumber yield.