*2.1.3 Study on water requirements of blueberry*

Reasonable water management is the basic guarantee for the high fruit yield and quality of blueberry [18–20]. Clarifying the water requirement of blueberry is a precondition for scientific management of blueberry orchard. In this study, weighing lysimeters were used to determine actual evapotranspiration (ET) of young seedlings of "Brightwell" rabbiteye blueberry and "Misty" southern highbush blueberry under different irrigation regimes. Effects of different irrigation regimes on seedling growth, total water consumption, and water-use efficiency (WUE) were also investigated. The results show that net increment of dry weight (IDW) per plant and total water consumption (TWC) per plant of two cultivar seedlings both elevate with increasing amount of irrigation, while water-use efficiency is lowest under 50% ET condition and the highest under 75% ET condition. As for "Brightwell," 125% ET treatments had similar values for IDW and WUE compared to 100% ET plants, whereas TWC was significantly higher than that of the control (100% ET). IDW and TWC in 50 and 75% ET treatments were significantly lower than that of the control, whereas no significant (*P* > 0.05) differences in WUE were observed. As for "Misty," IDW and TWC in 125% ET treatments were significantly higher than that of the control (100% ET), whereas WUE was not significantly different from that of the control (100% ET). IDW in 75% ET treatment was slightly lower than that of the control, and TWC was significantly lower than that of the control, whereas WUE was significantly higher than that of the control. IDW, TWC, and WUE in 50% ET treatment were all significantly lower than that of the control (**Figure 4**). It is concluded that the optimum irrigation treatment for "Brightwell" and "Misty" in southern China are 100 and 75% ET, respectively [21].

Water requirement estimation is one of the important aspects in crop water requirement research. Crop water requirement estimation by pan evaporation has been extensively used worldwide due to simplicity and low cost of the technique [22–24]. Pan evaporation method takes into account temperature, humidity, wind speed, solar radiation, and other meteorological factors, which are the same factors that affect crop

#### **Figure 4.**

*Effects of different irrigation treatments on net increment of dry weight per plant, total water consumption, and water-use efficiency of seedlings of* Vaccinium ashei *"Brightwell" and* V. corymbosum *"misty." different lowercases in the same column indicate the significant difference (P* ≤ *0.05) among different treatments of the same cultivar.*

#### **Figure 5.**

*The relationship between measured and estimated evapotranspiration for young seedlings of* Vaccinium ashei *"Brightwell" and* V. corymbosum *"misty."*

transpiration rate. In order to clarify the feasibility of water requirement estimation by water surface evaporation, actual water requirement of young seedlings of "Brightwell" rabbiteye blueberry (*Vaccinium ashei*) and "Misty" southern highbush blueberry (*V. corymbosum*) was measured by weighing lysimeter in this study. Simultaneously, water surface evaporation above the canopy was estimated using the standard 20 cm evaporation pan. The relationship between actual water requirement and water surface evaporation was studied, and the water requirement model based on water surface evaporation was established: *Q* = *D*<sup>2</sup> × *E*p-20 × *k*/1000, in which *Q* is the plant water use within a certain period, *D* is the diameter of the plant at drip line (cm), *E*p-20 is the measured evaporation from the standard 20 cm evaporation pan (cm), and *k* is the pan coefficient. The regression analysis results showed that estimation model for water requirement of "Brightwell" was *Q* = *D*<sup>2</sup> × *E*p-20 × 0.282/1000, and estimation model for water requirement of "Misty" was *Q* = *D*<sup>2</sup> × *E*p-20 × 0.291/1000. According to the water requirement estimation model, the fitting value of evapotranspiration was obtained, and regression analysis was conducted for the relevance between estimated and measured evapotranspiration. As illustrated in **Figure 5** there were significant positive correlations between the measured and estimated evapotranspiration (*P* < 0.01) in both cultivars, indicating that actual water requirement estimation by water surface evaporation above the canopy is feasible and effective. Our results provide reference and guidance for water management of rabbiteye blueberry under the similar climatic and geographical conditions.

#### **2.2 Future challenges**

Water management is the key factor for the success of blueberry growth. The water ecophysiology of blueberry should be further studied from the following aspects:

I.Study on blueberry water ecophysiology in the context of global climate change. Global climate change will increase the frequency and intensity of extreme weather events, which makes the blueberry growth face serious environmental challenges. Research on the ecophysiological response

**91**

**3.1 Experiment setup**

*The Developing Blueberry Industry in China DOI: http://dx.doi.org/10.5772/intechopen.88225*

strategy to cope with global climate change.

tion screening system needs to be further improved.

mechanism of water, under the global environmental change scenario, could provide the scientific evidence for developing cultural and breeding

II.Study on reliable and efficient evaluation and screening system for blueberry drought and waterlogging resistance. Plant stress resistance is a complex and comprehensive trait affected by many factors. At present, there is no widely accepted evaluation method, and the resistance evalua-

III.Study on the water requirement of blueberry under open-field and protected cultivation conditions. Systematic studies should be carried out on the dynamic of water requirement of different blueberry varieties at different growth stages, so as to provide theoretical basis and technical support for resource**-**saving and

IV.Estimation of water consumption of blueberry orchard at regional scale. Along with the increase in blueberry growing areas, blueberry orchards have gradually become an important vegetation type. It is of great significance to research the water consumption of blueberry orchards at regional scale for the design of

energy**-**efficient water management system of blueberry orchards.

irrigation system and rational allocation of water resources.

in blueberry cultivation, that prefers acidic organic matter.

**3. Effect of vinegar residue on soil properties and blueberry growth**

Blueberry grows in acidic soil with high organic content [25]. Generally it is necessary to add a large number of organic materials for soil amelioration [26] due to its low content of soil organic matter and other factors in commercial cultivation in China. Therefore, exploring suitable acidic organic materials has become one of the basic factors to ensure the sustainable development of blueberry cultivation in China. Vinegar residue, a unique organic material, is a by-product of traditional vinegar-making industry in China. Resource of vinegar residue is abundant, as there is 2.6 million tons of vinegar residue produced annually by just one enterprise, Jiangsu Zhenjiang Hengshun Sauce and Vinegar Co., Ltd. [27]. Vinegar residue has high crude fiber content, strong acidity, and high moisture content, which makes it difficult to be disposed [28]. It is reported that vinegar residue could ameliorate soil structure and increase soil organic matter content by its large amount of grain husks [29]. Besides, it contains high organic matter, protein, as well as N, P, and K nutrients, making it to possess potential in agricultural resource business, especially

Therefore, the effect of vinegar residue on soil physical and chemical properties, enzymatic activities, growth of blueberry, nutrient uptake, and fruit quality should be studied. And the effect of vinegar residue on the composition and diversity of rhizosphere microbial community of blueberry should further be analyzed. By this research we would clarify the effect of vinegar residue on the growth of blueberry and the mechanism revealed from the perspective of soil amelioration, in order to provide

The pot experiment was carried out in the blueberry nursery of the Institute of Botany, Chinese Academy of Sciences, Jiangsu province, in March 2016. And three treatments were set up as CK was pure soil; VR1 was V (vinegar residue),

scientific basis for the application of vinegar residue on blueberry cultivation.

*Modern Fruit Industry*

**Figure 5.**

*"Brightwell" and* V. corymbosum *"misty."*

was established: *Q* = *D*<sup>2</sup>

"Brightwell" was *Q* = *D*<sup>2</sup>

**2.2 Future challenges**

ment of "Misty" was *Q* = *D*<sup>2</sup>

*The relationship between measured and estimated evapotranspiration for young seedlings of* Vaccinium ashei

transpiration rate. In order to clarify the feasibility of water requirement estimation by water surface evaporation, actual water requirement of young seedlings of "Brightwell" rabbiteye blueberry (*Vaccinium ashei*) and "Misty" southern highbush blueberry (*V. corymbosum*) was measured by weighing lysimeter in this study. Simultaneously, water surface evaporation above the canopy was estimated using the standard 20 cm evaporation pan. The relationship between actual water requirement and water surface evaporation was studied, and the water requirement model based on water surface evaporation

certain period, *D* is the diameter of the plant at drip line (cm), *E*p-20 is the measured evaporation from the standard 20 cm evaporation pan (cm), and *k* is the pan coefficient. The regression analysis results showed that estimation model for water requirement of

estimation model, the fitting value of evapotranspiration was obtained, and regression analysis was conducted for the relevance between estimated and measured evapotranspiration. As illustrated in **Figure 5** there were significant positive correlations between the measured and estimated evapotranspiration (*P* < 0.01) in both cultivars, indicating that actual water requirement estimation by water surface evaporation above the canopy is feasible and effective. Our results provide reference and guidance for water management of rabbiteye blueberry under the similar climatic and geographical conditions.

Water management is the key factor for the success of blueberry growth. The water

I.Study on blueberry water ecophysiology in the context of global climate change. Global climate change will increase the frequency and intensity of extreme weather events, which makes the blueberry growth face serious environmental challenges. Research on the ecophysiological response

ecophysiology of blueberry should be further studied from the following aspects:

× *E*p-20 × *k*/1000, in which *Q* is the plant water use within a

× *E*p-20 × 0.282/1000, and estimation model for water require-

× *E*p-20 × 0.291/1000. According to the water requirement

**90**

mechanism of water, under the global environmental change scenario, could provide the scientific evidence for developing cultural and breeding strategy to cope with global climate change.

