The world’s most drought tolerant grass is now available in Perth. A trial was conducted by Melbourne Polytechnic to determine if TifTuf shows the same drought tolerance in Australia that it has shown in America. In American it has proven to use 38% less water on average than other varieties. The possibilities for this grass to have a positive impact in the Australian turf industry are enormous.
TifTuf was bred by the University of Georgia and chosen out of 30 000 different cultivars for its superior drought and shade tolerance and wear resistance. This has been a process of 25 years of R & D and trials.
Drought tolerance is when plants experience drought but don’t suffer the physiological damage and can retain green colour and even some growth (compared to drought avoidance and drought escape when the plant shuts down and becomes dormant losing colour and vigour). The plant may exhibit drought tolerance by osmotic adjustment in their cells to retain water and avoid wilt and leaf firing, or by processing stress compounds that protect cell membranes and allow them to continue to function. Studies in America have proved that TifTuf gets its superior drought tolerance to a combination of these physiological mechanisms within the plant. The University of Queensland has also showed the importance of rhizomes in couch drought resistance, which attributes to greater carbohydrate storage to maintain green colour longer in drought.
Polytechnic in Melbourne tested the drought tolerance of 4 common couch grass cultivars, Wintergreen, Legend, Santa Anna and TifTuf. The testing was done in mid-February to mid-March. The report observed the effect of summer evaporation (ET) as well as the effect of prolonged drought on green colour and the rhizome production of the 4 cultivars.
In mid – February, when all cultivars had successfully established a full and mature grass cover an episode of imposed moisture stress resulted in Wintergreen suffering severe yellowing and leaf firing. All 3 wintergreen replicates were affected, whilst all the other replicates from the other cultivars were unaffected. This resulted in Wintergreen being removed from further testing as it clearly showed inferior drought tolerance and had already failed. Measurement continued the remaining 3 cultivars.
Towards the end of the month long droughting from the 11th of March to 12th April, different replicates of Legend and Santa Anna lost green colour and showed visible signs of water stress, such as leaf rolling, leaf bronzing or bleaching. TifTuf remained consistently green.
Although there was no difference in ET rate between the 3 cultivars, there was a visible difference in colour retention. This points to TitTuf better exploiting a drought tolerance mechanism that the others did not.
In all 3 cultivars, root depth was to the full depth, and there was no observable difference in root density. Santa Anna and Wintergreen appeared devoid of rhizomes, Legend had some short but visible rhizomes and TifTuf had a noticeably higher level of rhizome production. Rhizome development can be slow in couch grass, often taking into the second summer of establishment to fully develop. Th early appearance of rhizomes in TifTuf was unexpected.
- The drought damage to Wintergreen during the lead in to the trial clearly demonstrated an inferior drought tolerance compared to the other couch cultivars.
- After prolonged drought, TifTuf retained green colour longer than the other cultivars.
- TifTuf produced more rhizomes than the other cultivars, which might contribute to better drought tolerance.
- The fact there was no difference in ET rates between TifTuf, Santa Anna and Legend supports the research that TifTuf uses physiological mechanisms when executing its superior drought tolerance