Glycine javanica cv. Tinaroo and green panic were sown together in May 1962 in all possible sowing-rate combinations of 2, 4, 8 and 16 lb/ac for the former and of 0, 0.5, 1, 2 and 4 lb/ac for the latter, and survival was followed for 2.5 years. Plant density of each species was dependent solely on the sowing rate of that species. There was no evidence of interspecific competition under these conditions, where neither species made sufficient growth to warrant yield samplings. Sparse stands of both species were present at the end of the study, though green panic at lower rates showed an increase in plant density; G. javanica stands gradually declined at all sowing rates

Cameron, D.G.

Courtice, J.

English

Queensland DAF eResearch Archive

QUEENSLAND DEPARTMENT OF PRIMARY INDUSTRIES DIVISION OF PLANT l'NDUSTRY BULLETIN No. 472 EFFECT OF SOWING RATE OF GLYCINE AND GREEN PANIC MIXTURES ON ESTABLISHMENT AND SURVIVAL UNDER DRY CONDITIONS By D. G. CAMERON, B.Sc.Agr., and J. C'OURTICE, Q.D.A. SUMMARY The effect of varying the seeding rates of Tinaroo glycine (Glycine javanica) and green panic (Panicum maximum var. trichoglume) on the establishment and survival of populations of both species was studied in an area which receives a mean annual rainfall of 27 · 7 6 in. The soil was a dry phase of a normally fertile alluvial clay loam. Plant density of each species was dependent solely on the seeding rate of that species. There was no evidence of inter-species competition under conditions where neither species made sufficient growth to warrant yield samplings during the 2-! years of observations. Sparse stands of both species were present at the conclusion of the study, though green panic at lower planting rates showed an increasing plant density. The glycine stand was gradually declining at all planting rates. I. INTRODUCTION Of the more recently introduced subtropical and tropical pasture plants, one of the most valuable on fertile soils is glycine (usually known as Glycine javanica L.). A wide range of this species has shown considerable promise in nurseries on alluvial soils of the Callide Valley in Central Queensland. In early field plantings of the cultivar Tinaroo, slow early growth and poor 'persistence occurred. In line with the reports of Codd and Myburgh (1949) and Tow ( 1960), it appeared that most mortalities occurred in the seedling year, but no critical data were available to confirm or reject this. The experiment reported here was designed to study the effects of competition on glycine establishment by varying the seeding rates of both glycine and the companion grass. "Queensland- Journal of Agricultural and Animal Sciences", Vol. 26, 1969 c 210 D. G. CAMERON AND J. COURTICE II. MATERIALS AND METHODS The experiment was located at Biloela Research Station (lat. 24 ° 24'S., long. 150° 30'E.) at an elevation of 568 ft above mean sea level. The mean annual rainfall is 27 · 76 in. and the mean daily maximum temperature ranges from 70·9°F in July to 92·5°F in January. Mean daily minimum temperature ranges from 39·8°F in July to 67·5°F in January. The soil is a grey brown clay loam of alluvial origin. A 20 x 4 randomized block design was used, with three blocks located on .a light-textured, poorly structured, more arid phase with a slight slope and 1he fourth on a slightly moister, fairly level situation. All combinations of the following Tinaroo glycine and green panic (Panicum maximum var. trichoglume (K. Schum.) Eyles) sowing rates were used: Glycine 2 lb/ac) I Green panic Nil Glycine 4 lb/ac l Green panic 0 · 5 lb I ac x Green panic 1 lb I ac Glycine 8 lb/ac Green panic 2 lb I ac Glycine 16 lb/ac Green panic 4 lb I ac Plots were contiguous and measured 30 lk x 30 lk. After appropriate rhizo-bium inoculation of the glycine seed, the legume and grass seeds were mixed with sawdust and hand-broadcast. Sowing commenced in overcast weather on March 9, 1962, following 1·50 in. of rain during the previous week. Only one block was planted before heavy rain interfered, and planting was completed on March 11. Seed in the first block was not covered, but a mechanical pronged weeder was used to cover the seed in the last three blocks. The plants were grown entirely on rainfall, which was above average for April and May and slightly above average over the 7 months after planting-I 0 · 31 in. against an average of 9 · 53 in. At no stage was sufficient growth made to justify yield sampling. However, the area was grazed on a number of occasions over the following 3 years. Counts of both glycine and green panic plants were made on three occasions. On May 1, 1962, two observers each counted one 21 in. x 42 in. quadrat per plot. On October 29, 1962, and October 14, 1964, two observers were again used, with a 5 x 2 lk quadrat counted two and three times per plot per observer respectively. III. RESULTS Plant counts are shown in Tables 1 and 2. Glycine density was sensitive only to glycine seeding rate, the highest rate giving highly significant increases in density over all other treatments. GLYCINE AND GREEN PANIC 211 TABLE 1 SURVIVAL OF GLYCINE PLANTS BETWEEN MAY 1962 AND OCTOBER 1964 Mean Number of Plants/100 sq lk Percentage Survival (Derived) Treatment 1.v.62 29.x.62 14.x.64 242 days 957 days ---Al Glycine 2 lb/ ac .. 6·3 3·9 2·2 61 34 A2 Glycine 4 lb/ ac .. 8·4 8·1 3·2 97 38 A3 Glycine 8 lb/ac .. 16·3 14·4 4-1 89 25 A4 Glycine 16 lb/ac .. 40·9 25·3 4·3 62 11 BO Green panic 0 lb/ ac 20·3 14·3 2·9 70 14 Bl Green panic t lb/ac 15-6 14·2 4·3 91 28 B2 Green panic 1 lb/ac 16-4 11-6 4·7 71 28 B3 Green panic 2 lb/ ac 18·9 10·8 2·8 57 12 B4 Green panic 4 lb/ ac 18·7 13·5 2·3 72 12 --Significance A4> >A3 A4> >A3 Not Analysed .. . . A3,A4> >Al, A3,A4> >Al, A2 A2 TABLE 2 SURVIVAL OF GREEN PANIC PLANTS BETWE~N MAY 1962 AND OCTOBER 1964 Mean Number of Plants/100 sq lk Percentage Survival (Derived) Treatment 1.v.62 29.x.62 14.x.64 242 days 957 days --Al Glycine 2 lb/ ac 13·5 11-7 11·4 87 85 A2 Glycine 4 lb/ac 11·3 13-5 8·8 119 78 A3 Glycine 8 lb/ ac 9·8 13-4 10·2 137 104 A4 Glycine 16 lb/ac 9·1 9·2 9·8 101 108 BO Green panic 0 lb/ ac 0 0 1-7 Bl Green panic t lb/ac 2·5 4·2 6·2 168 257 B2 Green panic 1 lb/ ac 7-3 6-2 8·3 88 115 B3 Green panic 2 lb/ac 10·3 13-8 9·9 132 96 B4 Green panic 4 lb/ ac 29·4 27·9 16·7 95 57 --Significance B4> >Bl, B2, B4> >Bl,B2, B4> >Bl,B2, B3 B3 B3 B3>Bl B3>B2 B3>Bl Green panic density was sensitive only to green panic seeding rate, with ;again a highly significant increase in stand density resulting from the highest seeding rate ( 4 lb I ac), an effect which persisted until the end of the trial. There is a strong suggestion in the data that the percentage mortality of green panic was proportional to the initial seeding rate of the grass. The final 212 D. G. CAMERON AND J. COURTICE stand represented only 57 % of the initial count at the heaviest rate but the lowest two seeding rates recorded an actual increase in stand. This trend was not established for glycine, which showed a gradual decline throughout the duration of the trial. IV. DISCUSSION In the plant introduction nursery at Biloela, with widely spaced rows and dean cultivated inter-rows, the various glycine cultivars grow particularly well, .showing considerable promise as potential pasture species. Field performance, 'however, has been much more erratic. In isolated cases with better water relations, adequate levels of growth were obtained. In the present experiment three blocks were found to be on a particularly dry phase of this normally quite fertile soil. Here even the well-adapted green panic failed to achieve much growth. However, there were no significant differences between blocks in the populations recorded even though visually better growth occurred on the lower-lying fourth block of the experiment. Despite the generally harsh conditions, 34 % of the initial population of glycine planted at 2 lb/ac and 11 % of the heaviest rate (16 lb/ac) population were still present 2t yr later, though' the glycine stand steadily declined over the full period of observations. The stands of glycine and green panic were solely dependent on their own planting rates, there being no evidence of inter-species competition. Tow ( 1967) reported on a similar experiment on the fertile basaltic soils of the Atherton Tablelands (lat. 17° 17' S., elevation 2,466 ft. above mean .sea level; mean annual rainfall 53 · 99 in.). Under ·the much more favourable environment than at Biloela, there was a vigorous early growth of green panic and weedy species (absent at Biloela), which cause major mortalities in the glycine populations, especially in the first year. Two years after planting and subsequent to the initial strong competition from the green panic, Tow still had 6-11 glycine plants per 100 sq lk, compared with 2-4 plants at Biloela 2t yr after planting. On the other hand, green panic stands were vastly different. These finally were 60-100 plants per 100 sq lk on the Atherton Tableland but only 6-16 plants under the much drier conditions at Biloela. Initial plant densities at Biloela were much lower than those reported by Tow. This may be accounted for in part by the fact that an extra 20 days elapsed before the first stand count was made, while no supplementary irrigation was used at this stage at Biloela. The results of the two centres taken together would suggest that, in regard to both establishment and persistence, glycine plants are more susceptible to :competition for factors other than moisture. At Biloela there was little if any GLYCINE AND GREEN PANIC 213 competition for light, which would have been considerable in Tow's experiment ,despite frequent mowing. Tow also indicated that the two species compete strongly for available nitrogen. At Biloela, lack of moisture would have restricted competition in this direction. The ideal seeding rate for the quality of green panic seed used in the present trial appears to have been between 1 and 2 lb/ac. A build-up in plants .from self-sown seed occurred where the seeding rate was lower. A decline in stand occurred at the higher rates. V. ACKNOWLEDGEMENTS Statistical analysis of the data was carried out by the Biometry Branch .of the Department of Primary Industries, to which acknowledgement is made. REFERENCES CODD, L. E., and MYBURGH, S. J. (1949).-Glycine javanica as a soil conserving legume. Fmg S. Afr. 24:471. Tow, P. G. (1960).-Some ways of establishing glycine. Qd Agric. J. 86:425. Tow, P. G. (1967).-Sowing rate, survival and productivity of green panic-glycine mixtures. Qd J. Agric. Anim. Sci. 24: 141. (Received for publication December 8, 1967) D. G. Cameron is an officer of the Agriculture Branch, Queensland Department of Primary Industries, stationed at Biloela Research Station, Biloela. J. Courtice was previously an officer of the Department. 

Effect of sowing rate of glycine and green panic mixtures on establishment and survival under dry conditions

https://era.daf.qld.gov.au/id/eprint/13141/1/QJAAS_26%5B2%5D_1969_pp209-213_cameron%26courtice.pdf

Effect of sowing rate of glycine and green panic mixtures on establishment and survival under dry conditions

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