The amount of plant-available water removed from the soil by plants and evaporation from the soil surface. For soils of high silt content 2.4 should be used. To this regard, Parra et al. experiment was established under a divided plot experimental design in random Even though enough PAW may be available for good plant growth, the plant may wilt during the day when potential evapotranspiration (PET) is high. The evaluation was done during flowering, fruit set, and harvest. (Temporary wilting of fruiting crops such as squash and cucumbers on a hot summer afternoon is not necessarily a sign of inadequate watering–this can be a sign of normal photosynthesis at its water-demanding peak.) Saturated (wet) soil. This water is held tightly in thin films around soil particles and is unavailable to plants. Open Special Issues, ● Cooperative Extension is based at North Carolina's two land-grant institutions, second cycle. Capillary water (lightly shaded areas ) in soil pores is available to plants. Scientific Research Figure 8. Harvest variables. In the field, these treatments were establishes under an experimental plot design divided into complete random blocks in the factorial arrangement with six replicates and each tree was a replicate. It is the difference between the volume of water stored when the soil is at field capacity and the volume still remaining when the soil reaches the permanent wilting point (the lower limit), as shown in Figure 6. (iii) Permanent Wilting: A permanent wilting is that state in the loss of turgidity of leaves when they do not regain their turgidity even on being placed in a saturated atmosphere. 4.2.3.3 Plant Available Water. ● This is the water retained in soil pores after gravitational water has drained. When a significant difference was found, a Tukey (p ≤ 0.05) mean comparison test was done. Under this condition it contains the greatest amount of water that is potentially available to plants. Most crops will recover overnight from temporary wilting if less than 50 percent of the PAW has been depleted. The 40 vegetative flows were tagged in every direction of the compass (North, South, East, and West) in each tree. The pore volume is actually a reservoir for holding water. Soil moisture and agronomic practice levels were selected based on the physical characteristics of the soil, the utilizable moisture (UM; %) ranged between a field capacity (FC = 37%) and a permanent wilting point (PWP = 20%); but for the purposes of this research a temporal wilting point (TWP = 13%), lower than PWP, was selected. It varies in different types of soil, for example, clay has higher Permanent wiling percentage (PWP) than sand. Figure 3 represents a "wet" (saturated) soil immediately after a large rainfall. These factors are phytosanitary problems, little genetic diversity in the grown varieties, deficient agronomical handling, difficulty in vegetative propagation, and production alternancy [1] . Evapotranspiration is the process by which water is lost from the soil to the atmosphere by evaporation from the soil surface and by the transpiration process of plants growing in the soil. For example, consider corn growing in a sandy loam soil three days after a soaking rain. M.B. This is called temporary wilting. Typical units are inches of PAW per inch of soil depth or inches of PAW per foot of soil depth. Irrigation scheduling decisions should be adjusted to reflect changes in crop water consumption during the growing season. 2) Harvest end date. Temporary wilting will occur in many crops on a hot windy day, but the plants recover in the cooler portion of the day. In litchi, high day temperatures in the shoot and high root temperatures promoted vegetative growth and reduced or eliminated flowering [19] . The increase in fruit size was recorded from fruit set to its physiological maturity. The authors declare no conflicts of interest. Water retained in soil pores after gravitational water has drained or is held loosely around soil particles by surface tension. When the plant has removed all available water, the soil's water content has reached the permanent wilting point (PWP), as shown in Figure 5. As with rooting depth, water use rate is a function of the crop's stage of development, as shown in Figure 13. The most critical irrigation period typically begins just before the reproductive stage and lasts about 30 to 40 days to the end of the fruit enlargement or grain development stage. The trees with permanent irrigation (PI), flowering percentages of 52% were obtained, as well as fruits with 3.6 cm diameter, 0.6 cm thick arils, individual fruit weight of 31 g and a yield of 178 kg for tree. An effective irrigation schedule helps to maximize profit while minimizing water and energy use. Water distribution in a soil at field capacity. From the yield standpoint, applying irrigation water at silking would be worth four times more than if the same amount of water was applied during the knee-high stage. Physical and chemical barriers in the soil often limit actual rooting depths to less than potential rooting depth. At this stage, there is a general loss of turgidity and plants do not recover even after watering. Effective root depth is further influenced by the stage of crop development. Because the root system is fully developed by the beginning of the reproductive period, irrigation amounts should be computed to replace the depleted PAW within the effective root zone (12 inches). being a replicate. The effective root depth is the depth that should be used to compute the volume of PAW in the soil reservoir. Soil properties that influence the plant's rooting depth. Read our From the temperature and precipitation records in the study site, it was observed that flowering induction of rambutan was influenced by exogenous factors, since all the treatments showed floral differentiation in the vegetative shoots. Soil moisture. 3) Yield per tree. Equation used to obtain the soil moisture. Therefore, the allowable depletion volume generally recommended in North Carolina is 50 percent (Figure 9). Plant can’t meet the transpiration. Table 3. this, the objective of the present study was to evaluate the effect of the The research was carried out in the “La Chinita” commercial orchard, located on km. This process of wilting during the day and recovering at night is referred to as temporary wilting. Measuring Soil Moisture Potential in Situ (Field): For example, the allowable depletion recommended for some drought-sensitive crops (vegetable crops in particular) is only 20 percent during critical stages of development. Permanent plant wilting occurs when the volumetric water content in the soil is too low for the plant’s roots to extract water. We used 48 rambutan trees in Same letter in a bars shows no significant statistical difference alpha = 0.05. floral bud development and maximize the number of inflorescences per node [20] . out in the “La Chinita” commercial orchard located on KM. This publication printed on: Nov. 27, 2020, Soil, Water and Crop Characteristics Important to Irrigation Scheduling, Skip to Crop Sensitivity to Drought Stress, Measuring Soil Water for Irrigation Scheduling: Monitoring Methods and Devices, NC