What is the purpose of using endophytic fungi in grass development?

Using endophytic fungi in grass development primarily serves to increase resistance to pests and diseases. Endophytes are beneficial fungi that live within plant tissues, providing a symbiotic relationship that enhances the plant's overall health. These fungi produce various alkaloids and metabolites that can deter herbivores and inhibit the growth of pathogens, effectively bolstering the plant's defenses.

The other choices, while they highlight important aspects of lawn and ornamental practices, do not capture the primary benefit of endophytic fungi. Improved soil moisture retention relates more to soil management and amendments, and though endophytic associations can indirectly contribute to a plant’s overall resilience which may aid in flowering and aesthetic qualities, those are not their primary functions. Promoting faster growth rates is generally more associated with nutrient availability rather than the presence of endophytic fungi. Therefore, the role of endophytes is crucial for keeping grasses healthy amidst biotic stressors, making increased resistance to pests and diseases the correct answer.