As most of California is in extreme drought, people have been cutting back on the water they use in their yards, resulting in barren lawns of grass. On the other hand, those who water excessively are squandering the limited water supply. The purpose of this experiment is to determine if mycorrhizae will increase the drought tolerance of Lolium perenne. Four experimental groups were organized representing different watering conditions, including 100%, 50%, 20%, and 10% water, which were found in soil-carrying capacity studies. The 100% and 50% groups represent very well watered and sufficient watering, while the 20% and 10% groups embody drought conditions to varying degrees. The different watering conditions began one month after Lolium perenne was planted and mycorrhizae was added to experimental groups. Controls were not inoculated with mycorrhizae, and experimental groups were inoculated with equal amounts of mycorrhizae. Observations of color and measurements of grass height were taken every other day. At the end of the experimental period, data on average grass height, dry mass, and blade density were collected.

Overall, the difference between the mycorrhizae-inoculated group, with an average height of 12.6cm, and the non-mycorrhizae group, with an average height of 13.4cm was extremely statistically signficant but did not favor mycorrhizae. The 100% condition exhibited no statistically significant differences in grass height. However, the 50% watering condition does show a statistically significant difference, where the non-mycorrhizae group is taller at 12.1cm, and the mycorrhizae group is at 11.0cm. The 20% conditon, where the control averages 14.8cm and 13.4cm for control and experimental has a mean of 13.3cm, as well as the 10% condition, with an average of 14.3cm and 13.4cm for control and experimental groups, respectively, showed statisical significance. The overall dry mass of 3.8cm2 samples are 4.70 g for the mycorrhizae group and 5.99 g for the non mycorrhizae group, which shows statistical significance. The 10% and 20% groups also show a significantly greater mass in the non-mycorrhizae group. The blade density, which has a mean of 116.4 blades/ 3.8cm2 in the mycorrhizae group and 100.3 blades/3.8cm2 in the non-mycorrhizae group shows no statistical significance, but it demonstrates potential for significance in the repeat study that is in progress. This repeat study will focus more on blade density rather than grass height, which does not necessarily indicate a healthier grass. Finally, qualitative data did not prove to be of importance. Other future studies could test the effect of mycorrhizae on the yield of popular crops. Therefore, the hypothesis that mycorrhizae would increase drought tolerance is not supported statistically, but there is evidence to indicate that mycorrhizae will increase blade density, even in drought conditions. These results can be explained by networks between roots that are strengthened by mycorrhizae. These networks could have allowed for nutrients in the soil to be better distributed accounting for a greater blade density but may have sacrificed height.