## 3 Drought Stress and Plant Growth  
Drought stress is well recognized as a limiting factor which alters multiple aspects of plant growth and development. Germination of seeds, health and coleoptile length are foremost for the plant progression [36]. Seed germination is the primary aspect of growth which is sensitive to drought stress. Noteworthy alterations are observed in the seed germination of a plethora of plant species, including some of the most widely cultivated crops such as maize [37], sorghum [38] and wheat [39].  
Visible symptoms of plant exposed to water scarcity in the initial vegetative stage are leaf wilting, decline in plant height and interruption in establishment of buds and flowers [40]. Drought conditions also limit the uptake of nutrients by the plants due to limited soil moisture, leading to decreased stem length [41]. Shoot length was also reduced under water deficit conditions in _Lathyrus sativus_ L. [42].  
Figure 1: Effect of drought stress on plant growth and development (modified from [PERSON] et al. [35]).  
In conditions of water deficit, plants seek to extract water from deeper soil layers by boosting their root architecture [43]. Moreover, water availability is primarily recognized by roots, which in turn regulates its growth and organization characteristics such as root length, spread, number and length of lateral roots [44]. Roots are crucial for different biological activities and plant yield, for instance nutrient accumulation and water absorption, and they are also involved in rhizosphere symbiotic associations with other microorganisms. Drought stress escalated root length in _Crocus sativus_ L. [45]. Thus, a healthy root apparatus provides the benefit for sustenance of the escalation of plant growth, especially in the course of primary plant growth phase [46]. Escalation in root length is recognized as a useful strategy to increase soil water retention and nutrient accumulation to enhance plant biomass production [47]. Under water deficit, the plant root to shoot proportion generally improves, and, subsequently, the plant biomass decreases substantially [48].  
The leaf is the chief part of the plant where most of the photosynthetic products are synthetized. The number of leaves decreased when subjected to water stress in _Andrographis paniculate_[49]. Optimal leaf development and the maintenance of an adequate leaf area is vital for photosynthesis, which in turn is the main driver of plant growth. Water stress causes reduction in leaf area, which results in decreased photosynthesis, hence reducing the crop yield. Leaf area declined under water stress conditions in _Petroselinum crispum_ L. and in _Stevia rabaudiana_ plants to achieve stability among the water absorbed by roots and the water status of various plant parts [50; 51]. Reduction in leaf area is a drought avoidance strategy because declining leaf area results in a decreased water loss by the process of transpiration and this reduction in leaf area is attributable to the inhibition of leaf expansion by declined rate of cell division, which results in loss of cell turgidity [52]. Decrease in soil moisture causes a parallel reduction of leaf water content, which, in turn, induces a decline of turgor pressure of guard cells due to stomata closure [53]. Of note, the rate of premature leaf senescence is enhanced in drought environments [17].