COMPARISON OF THREE PLANT GROWTH REGULATORS AND UREA ON A CANTERBURY DAIRY PASTURE

Transcription

1 COMPARISON OF THREE PLANT GROWTH REGULATORS AND UREA ON A CANTERBURY DAIRY PASTURE S. Jing 1, 4, P.L. Crey 1, A. Roerts 2 nd G. Kerse 3 1 Lnd Reserch Services Ltd, Art Workshops, Lincoln University, Christchurch 2 Rvensdown Fertilizer Co-opertive Ltd, Pukekohe 3 Rvensdown Fertilizer Co-opertive Ltd, Christchurch 4 shung.jing@lrss.co.nz Astrcts Two plnt growth regultor (PGR) products currently ville in New Zelnd nd new Rvensdown PGR product-express TM*, ll sed on gierellic cid (GA 3 ), were pplied to Cnterury diry psture in lte winter (August) nd erly spring (Septemer) nd their effect on dry-mtter (DM) yield ws mesured. PGR tretments were compred with oth n ppliction of liquid ure (2 kg N/h) lone nd ure plus Express tretment. In the first hrvest of oth winter- nd spring-initited trils, month following PGR ppliction, the PGR tretments produced significnt increses in DM yield rnging from 18-51% over the control. These increses, however, did not extend to the second hrvest in either tril for ny of the PGR gents. The ppliction of ure incresed production in the 1 st hrvest y ~36% in oth trils ut this ws incresed to over 6% when comined with Express TM. No effect of the PGR ws pprent in the second hrvest where the ure tretment lone ws the highest DM producer. These trils showed some enefit in the use of PGR products when there is need to oost psture growth in erly spring ut these enefits lrgely disppered fter the first month following ppliction. Some future reserch my e useful to further optimise prmeters for the use of PGR products. Introduction Gierellic cid (GA 3 ) is nturlly occurring plnt growth regultor found in most plnt species. Since its discovery in the 195 s it hs een well studied for its effects on plnt growth (Morgn nd Mees 1956; Morgn nd Mees 1958; Scurfield nd Bull 1958) including on pstures (Scott 1959; Scurfield nd Biddiscome 1959) GA is produced y plnts in higher quntities in wrmer months. During the colder months, its production is low, hence plnt growth is slower. The ide ehind the ppliction of the hormone is tht it will stimulte cell expnsion, resulting in lef nd stem elongtion. Therefore, the optimum temperture for grss growth response to GA is in the cool seson when dys re shorter nd the psture is in this slow growth phse. Experimentl evidence from the UK indicted tht the most pproprite time for ppliction in UK ws Mrch (erly Spring) (Morgn nd Mees 1958) nd in Austrli, June nd July (Arnold et l. 1967; Biddiscome et l. 1962; Willims nd Arnold 1964). * Express TM is trdemrk of Rvensdown Fertiliser co-opertive Ltd. It is registered pursunt to the ACVM Act , No

2 Boosting winter growth of pstures hs een of interest in mny countries ut generlly the cost of using PGR products ws disincentive to their more widespred use (Scurfield nd Biddiscome 1959). In the New Zelnd dirying industry there hs een interest in oosting mid-winter to erly-spring psture growth when the lcttion seson hs just strted. The use of PGRs could e nother psture mngement tool to increse feed vilility during this time. Two trils were set up on Cnterury diry psture in lte winter nd spring 21, respectively, to test the growth response of psture to Rvensdown Express nd two other PGR products (effective ingredient GA 3 ). The min ojectives of these trils were to: 1. mesure the size of ny response in reltion to ppliction timing, 2. compre the effect of pplying liquid ure lone nd in conjunction with Express, nd 3. mesure how long ny response might lst. Mterils nd Methods A site ws selected on Cnterury diry frm ner Springston (43.63 S, E) on n Eyre soil (Immture Pllic) (soil test vlues: ph 5.9, P 19, S 6, C 8, Mg 32, K 11) with mixed perennil ryegrss/white clover psture. The two trils were set out on rndomised lock design with tretments replicted 6-times during lter winter (August) nd erly spring (Septemer) 21, when the monthly 1 cm soil tempertures were 7.9 C nd 9.5 C respectively. Ech plot ws 5 m long y.5m wide with.5 m uffers etween plots with grzing nimls excluded. Bsl fertilizer of 3 kg/h single superphosphte ws pplied to ll plots initilly. All plots were mowed 2-3 dys prior to ppliction of tretments. Two hrvests were tken for ech tril t pproximtely four-weekly intervls. The PGR products used in the trils were s follows: PstureGi (PGR1) contining 9% of gierellic cid (Orion Crop Protection Ltd. Aucklnd), ProGi SG (PGR2) contining 4% of gierellic cid (USA product), nd Rvensdown Express (Express)- contining 4% of gierellic cid. Thus six tretments were pplied: 1. Control 2. PGR-1 3. PGR-2 4. Express 5. Ure 6. Ure plus Express P: Olsen P; C, K nd Mg: Quick test units; S: ppm 2

3 DM (kg/h) DM (kg/h) All PGRs nd ure were pplied in dissolved form, the PGRs t the equivlent rte of 8g GA 3 /h nd the ure t 2 kg N/h, with coverge of 2 L/h. All products were pplied with surfctnt or wetting gent s directed to id ppliction. Results PGR responses PGR use incresed DM production significntly overll (Tle1; P<.1) from the control for the first hrvest from 18-36%, nd 26-51%, for the winter nd spring trils, respectively (Figures 1-2). In the second hrvest, however, DM production for the PGR tretments ws ctully lower thn the control ut not significntly different from ech other or the control for either tril. Express plus N The verge DM yield for ure ppliction for the first hrvest incresed y 36% nd 23% in winter nd spring trils, respectively, over the control (Figures 1-2). This incresed to over 6% when comined with Express in oth trils (P<.1). In the second hrvest, there were no significnt differences etween ny of the tretments. Tle 1. Dry-mtter yield for control vs. PGR tretments cross oth trils for hrvests 1 nd 2. Tretment Hrvest 1 Hrvest 2 Control PGR PGR Express Vlues with different letters re significntly different from ech other (P<.5) Tril 1 - August Tril 1 - August Control PGR-1 PGR-2 Express Control Express Ure Ure+ Express Hrvest 1 Hrvest 2 Hrvest 1 Hrvest 2 Figure 1. DM yield comprisons for the August ppliction etween PGR products (left) nd Express nd/or ure (right) over two hrvests. Columns with different letters re significntly different from ech other (P<.5) 3

4 DM (kg/h) DM (kg/h) Tril 2 - Septemer Tril 2 - Septemer Control PGR-1 PGR-2 Express Control Express Ure Ure+ Express c Hrvest 1 Hrvest 2 Hrvest 1 Hrvest 2 Figure 2. DM yield ccomprisons for the Septemer pplictions etween PGR1, PGR2 nd Express (left) nd/or ure (right) over two hrvests. Columns with different letters re significntly different from ech other (P<.5) Discussion PGR rtes used in previous psture reserch often used rtes rnging from 25-7g/h of ctive ingredient ut it ws noted tht, t these higher rtes, susequent growth ws depressed to the point thn the increse in DM yield otined from the use of GA 3 -sed PGRs in the first hrvest could e exceeded y the loss of production in the susequent hrvests (Scott 1959). Currently the recommended ppliction rtes re much lower t 5-1 g/h ctive ingredient nd these seem to the produce the most cost-effective responses with reduced side effects (Mtthew et l. 29). Whilst PGR tretments significntly incresed DM yield in hrvest 1 of oth trils, there ws trend for slight depressive effect to PGR use lone in the second hrvest lthough these differences were not sttisticlly significnt. Becuse the initil increse in DM yields is proly ssocited with n ltertion in the distriution of dry mtter rther thn with chnge in cron fixtion (Willims nd Arnold 1964) depressive effect could follow if this DM increse hs een t the expense of root growth nd nutrient uptke whilst soil tempertures remin low. In reviewing erlier work of the responses of pstures to GA 3, the optimum rection temperture is etween C in Austrli nd C in UK. Reported trils in NZ were either for utumn (Otgo; Scott 1959) or mid-winter (North Islnd; Percivl 198) so pucity of dt existed for Cnterury for lte-winter/erly-spring prior to these trils. Instructions for ppliction in New Zelnd provided y Nufrm (29) re to pply t soil tempertures from 5-16 C (Mtthew et l.29). Our results show tht responses were s gret for the second s first trils so the suggested rnge for soil tempertures t which responses will occur re not contrdicted y our dt. DM yields for our Express+N tretments showed much higher responses thn ure or PGR lone tretments, which ws t odds from previous NZ dt (Mtthew et l. 29; Percivl 198; Scott 1959) ut different ppliction rtes were used or in different regions. Our results show tht Cnterury pstures will e responsive to GA-sed PGRs, especilly in conjunction with N use, over the winter-spring shoulder months ut this my chnge depending on the previling climtic conditions. The prcticlities of using GA-sed products lso hve to e considered in tht pplictions re recommended to e mde no more thn 1-5 dys fter grzing. 4

5 Conclusions Increses in DM yields from 18-51% were chieved with the use of the three PGR products with mens for Express incresing from ~3% to over 6% in conjunction with N use. Generlly, PGR effects only lsted single hrvest with no significnt responses recorded in the second hrvest. Whilst the cost of PGR products hs decresed in reltive terms nd they re now more ffordle, their use is proly stop gp mesure for lte winter or erly spring when tempertures re still reltively low, sunlight hours re short nd there is n immedite feed requirement. PGR products provide nother tool to oost psture growth the in the erly prt of the lcttion seson ut these should not sustitute for good feed nd psture mngement. Further reserch is proly needed to optimise the performnce of GA 3 -sed products for locl wether conditions nd soil nutrient sttus. References Arnold GW, Bennett D, Willims CN (1967) Promotion of winter growth in pstures through growth sustnces nd photoperiod. Austrlin Journl of Agriculturl Reserch 18, 245- &. Biddiscome EF, Arnold GW, Scurfield G (1962) Effects of gierellic cid on psture nd niml production in winter. Austrlin Journl of Agriculturl Reserch 13, 4-&. Mtthew C, Hofmnn WA, Osorne MA (29) Psture response to gierellins: review nd recommendtions. New Zelnd Journl of Agriculturl Reserch 52, Morgn DG, Mees GC (1956) Gierellic cid nd the growth of crop plnts. Nture 178, Morgn DG, Mees GC (1958) Gierellic cid nd the growth of crop plnts. Journl of Agriculturl Science 5, Percivl NS (198) Cool-seson growth responses of kikuyu grss nd ryegrss to gierellic cid. New Zelnd Journl of Agriculturl Reserch 23, Scott RS (1959) Effect of gierellic cid nd nitrogen on winter growth of psture. New Zelnd Journl Agriculturl Reserch 2, Scurfield G, Biddiscome EF (1959) Effects of gierellic cid on winter psture production. Nture 183, Scurfield G, Bull JA (1958) The effects of gierellic cid on winter growth of Phlris tueros. Journl of the Austrlin Institute of Agriculturl Science 24, Thkur P, Kumr S, Mlik JA, Berger JD, Nyyr H (21) Cold stress effects on reproductive development in grin crops: An overview. Environmentl nd Experimentl Botny 67, 429. Willims CN, Arnold GW (1964). Winter growth stimultion y gierellin in differentilly grzed pstures of Phlris tueros. Austrlin Journl of Experimentl Agriculture nd Animl Husndry 4,