Forage dry-matter productivity variation of Panicum and Cynodon ecotypes in Malawi

H.D.C. Msiska

Lunyangwa Research Station
P.O. Box 59, Mzusu, Malawi

B.H. Dzowela

ILCA, P.O. Box 46847, Nairobi, Kenya

and

J.T. Munthali

Chitedze Research Station
P.O. Box 150, Lilongwe,
Malawi

Introduction
Materials and methods
Results and discussion
Conclusion
References

Abstract

Both Panicum maximum and Cynodon nlemfuensis strains have great variability in forage dry-matter productivity and responsiveness to nitrogen fertilizer application. This variability has been demonstrated and it warrants a wide selection potential for new strains to replace old cultivars in these two species.

Introduction

In recent years many developing countries including Malawi have realised the importance of local forage plant genetic resources. However, the lack of funds to facilitate wide-scale collection and detailed evaluation of the local germplasm has limited exploitation of these local forage plant genetic resources. Instead, imports of-both legumes and grasses have been done from Australia and other countries. Most of the imported materials are, however, locally represented. To minimise expenses on importations of seed, it was found necessary to critically look at local ecotypes to come up with some cultivars for different ecological niches. The evaluation work is limited by a lack of experience in local forage exploration and by availability of funds. Forage productivity evaluation is therefore limited to a few most promising germplasms namely Neonotonia, Panicum and Cynodon species. Only the work on Panicum maximum and Cynodon nlemfuensis is reported here.

Materials and methods

During the 1980/81 growing season, a forage plant collection trip was made to some parts of the central and northern regions. The target areas were chosen on the basis of climate and topography hence, seasonally waterlogged valleys (dambos), river courses and the eastern escarpments of the highland zones. Dambo and river courses were chosen to give an indication of forage species whose seed originally came from the inaccessible hills and valleys beyond the escarpments. Collections were made along roads crossing dambos, rivers and in some other places of ecological interest.

Vegetative materials were dug out and put in black polythene bags; water was poured in and then the bags were tied at the mouth. The most promising star and guinea grass materials based on one growing season single row nursery observation were put in two trials respectively as follows:

Trial 1: Star grass strains evaluation trial

Twenty-four entries from the southern African region and local collections were put in a split-plot design trial with two replicates. The plots which measured 9 square metres were split two-ways into three nitrogen fertilizer application rates of 20, 40 and 60 kg N/ha applied in the form of calcium ammonium nitrate (26% N) and three cutting regrowth intervals of 3, 6 and 9 weeks respectively.

Trial 2: Guinea grass (Panicum maximum Jacq.) strains evaluation trial

Fifteen collections, mostly indigenous to Malawi were planted in the same design as described in Trial 1. The only difference was that fertilizer rates of 0, 40 and 80 kg N/ha were applied. In both trials, the grasses were cut, weighed fresh and subsampled for the determination of dry matter after oven drying at 85°C for twenty-four hours.

Results and discussion

1. Star grass

Yield data for the star grass strains for the 1984/85 and 1985/86 growing seasons are presented in Tables 1, 2, 3 and 4. Two accessions, East Coast B and No. 343 Star gave the highest forage dry-matter yields and these were in excess of 5000 kg/ha. These are the more robust growing star grasses, with larger stolon and leaf material than the small-slandered leaf and stolon materials. Second ranking were those strains of 4000 kg/ha yield levels. These were Chololo, Ichinga, Monzi, Misuku, Camper Down, Thunda and Chinunkha. These were of intermediate stolon material. The least amounts of forage were produced by the three Malawian collections, Nyungwe, Meru and S.E. Namwera all of which gave yields of less than 2500 kg/ha. These were materials least robust in growth and appearing less aggressive in that their stolon growth was rather restricted; hence they formed open turfs. The two commercially popular cultivars, Muguga and No. 2 Star, that have since been grown at Chitedze Research Station, were intermediate, giving yields of about 3500 kg/ha.

The variability in forage productivity is explained by the fact that there were two different species in this collection. In the absence of critical taxonomic and botanical variety description, it was obvious that the material demonstrated a lot of physical differences. Plants that fitted the description with respect to Cynodon dactylon (Harlan and de Wet, 1969) were less robust in their growth habit. The more robust material probably belonged to C. nlemfuensis (Clayton and Harlan, 1970; Harlan, 1970).

Table 1. Forage DM yields (kg/ha) of Cynodon cultivars across two replicates in response to cutting regrowth intervals (1984/85 season).

Cultivars	3 weeks	6 weeks	9 weeks	Mean
1. Nyungwe	1840	2078	3303	2407
2. Chololo	2537	4088	5902	4142
3. East Court A+	2790	3153	4640	3528
4. Durban+	2053	2880	4828	3254
5. Thornville	2183	3070	4970	3408
6. Ichinga	2455	4450	5407	4104
7. Muguga	2393	3027	4690	3370
8. Monzi No. 2+	2210	4860	6950	4680
9. Baka	2142	2618	4492	3083
10. Phoka Court	2150	3452	5375	3659
11. No. 171 Star+	2810	3777	5538	4042
12. Coast Gross II+	2613	2658	4532	3268
13. No. 2 Star	1657	4043	4702	3467
14. Misuku	3597	5007	5758	4787
15. No. 161 Star+	2625	3043	5565	3744
16. Chilambula	2335	2858	6027	3740
17. Camper Down+	2832	5883	4893	4536
18. No. 343 Star+	4570	4700	6107	5126
19. S.E. Namwera	3198	2889	2503	2863
20. Thunda	4175	3538	4677	4130
21. Monsi No. 1+	2748	3418	4472	3546
22. Chinunkha	3865	4203	4820	4296
23. Meru	2308	2213	2845	2456
24. East Court B+	3105	4205	8105	5138
Means	2716	3589	5042

S.E. of cultivar means ± 640*
S.E. of cutting intervals means ± 121**
S.E. of interaction ± 209*
Overall C.V. 38%
+ introduced entries
Where

* is significance at P = 0.05
** is significance at P + 0.01

Increasing nitrogen levels generally resulted in significantly higher yields (P=0.05), but some strains were less responsive to nitrogen depending on the cutting regrowth intervals. Materials with a generally open turf responded poorly and lacked a response to increasing nitrogen fertilization. This was particularly true of the local Malawian ecotypes, Nyungwe, Phoka Court, Chololo, Thunda, Meru and a few imported strains No. 161 Star, No. 2 and Thomville. There was also a significant increase in forage DM yields in response to increasing cutting regrowth intervals (P=0.01). This was no doubt a consequence of increased forage maturity.

During the 1985/86-growing season, all strains responded to increased cutting regrowth intervals from 3 to 9 weeks (P=0.001) as shown in Table 3. There was also a significant response to increasing levels of nitrogen fertilization, although the levels of 20 and 40 kg/ha were not statistically different. The strains Thornville, Baka, Misuku and No. 161 Star were not responsive to increasing nitrogen fertilization (Table 4). In the analysis the differences between cultivars did not turn out significant however, the largest amounts of forage, in excess of 8000 kg/ha, were given by the strains East Coast A, Coast Cross II, No. 343 Star and Durban. The least amounts of forage, 6,500 kg/ha or less, was given by the strains, Meru, East Coast B. Chilambula and Phoka Court. The fact that in the second harvest year, No. 2 Star fell in the top ranking group while Muguga maintained its position in the intermediate yielding category, shows that Star No. 2, once it is fully established, has a high yielding potential.

Table 2. Forage DM yields (kg/ha) of Cynodon cultivars across two replicates in response to nitrogen fertilizer rates (1984/85 season).

Cultivars	N1 = 20	N2 = 40	N3 = 60	Mean
1. Nyungwe	2360	2512	2349	2407
2. Chololo	4130	4208	4088	4142
3. East Court A+	3075	3850	3658	3528
4. Durban+	2835	3520	3407	3254
5. Thornville	3483	3473	3267	3408
6. Ichinga	3725	4358	4228	4104
7. Muguga	2972	3465	3673	3370
8. Monzi No. 2+	4760	4605	4675	4680
9. Baka	2917	2712	3623	3083
10. Phoka Court	3114	4052	3812	3659
11. No. 171 Star+	3355	4228	4542	4042
12. Coast Gross II+	2470	3692	3642	3268
13. No. 2 Star	3380	3625	3397	3467
14. Misuku	4087	5012	5263	4787
15. No. 161 Star+	3978	3777	3478	3744
16. Chilambula	3198	3893	4128	3740
17. Camper Down+	3787	4883	4938	4536
18. No. 343 Star+	4813	5053	5510	5126
19. S.E. Namwera	2695	2675	3220	2863
20. Thunda	3802	4627	3962	4130
21. Monsi No. 1+	2822	4067	3750	3546
22. Chinunkha	4358	3978	4552	4296
23. Meru	2292	2483	2592	2456
24. East Court B+	4902	4660	5853	5138
Means	3471	3892	3984

S.E. of cultivar means ± 640*
S.E. of Nitrogen means ± 137*
S.E. of Interaction ± 671NS
Overall C.V. 38%
+ Introduced entries
Where * is significance at P=0.05
NS is not significant.

2. Guinea grass

Most of the locally collected strains have a higher yielding potential than the local standard cultivars, Ntchisi Panic and Hamil Panic. Notable in this case are selection H. selection o and Chololo Panic (Tables 5 and 6). These are generally leafier material which are generally of a very good regrowth potential, much better than either Ntchisi or Hamil Panic. The least producing were selections X and Makueni Panic, both of which are low growing and finer-leaved types. Both these strains were slow to establish a full canopy; as a result, they suffered considerably from weed competition during the establishment. The fact that they were smaller plant types could be explained by their belonging to a lower ploidy level than the majority of the more robust types.

Table 3. Forage DM yields (kg/ha) of Cynodon cultivars across two replicates in response to cutting regrowth intervals (1985/86 season).

Cultivars	3 weeks	6 weeks	9 weeks	Mean
1. Nyungwe	4430	6022	11883	7445
2. Chololo	4498	6354	12934	7929
3. East Court A+	6081	9536	13545	9654
4. Durban+	5022	7751	11335	8036
5. Thornville	4068	7865	9606	7180
6. Ichinga	4463	6614	11891	7656
7. Muguga	4357	6376	10390	7041
8. Monzi No. 2+	3857	7644	8555	6685
9. Baka	3817	7320	10510	7215
10. Phoka Court	4202	6356	8962	6507
11. No. 171 Star+	3408	7797	10349	7184
12. Coast Gross II+	6658	8345	11196	8733
13. No. 2 Star	5951	6969	11851	8257
14. Misuku	5246	5538	9540	6774
15. No. 161 Star+	3634	6903	11189	7242
16. Chilambula	5259	5756	8258	6424
17. Camper Down+	5091	6775	12341	8369
18. No. 343 Star+	4397	9006	1918	8440
19. S.E. Namwera	4762	6826	9064	6864
20. Thunda	5157	5620	10762	7186
21. Monsi No. 1+	3985	8073	9536	7198
22. Chinunkha	5757	6393	11623	7924
23. Meru	3610	6182	9279	6357
24. East Court B+	4942	6053	11556	6357
Means	4694	7003	10782

S.E. Cultivar ± 623NS
S.E. Cutting intervals
+ Introduced entries ± 331
Where *** is significance at P=0.001
NS is not significant.

All strains significantly increased in their forage productivity in response to increasing cutting regrowth intervals. While the response to increasing nitrogen fertilization turned out significant, there was a tendency for same strains to respond less to increasing nitrogen fertilization beyond N₂ which is 40 kg N/ha. Notable in this regard are selections C, M, J, K, D, H, B, Ntchisi Panic and Hamil Panic.

Table 4. Forage DM yields (kg/ha) across of Cynodon cultivars two replicates in response to nitrogen fertilization (1985/86 season).

Cultivars	N1=20 kg/ha	N2=40 kg/ha	N3=60 kg/ha	Mean
1. Nyungwe	7448	7256	7631	7445
2. Chololo	7083	7894	8809	7929
3. East Court A+	8822	9975	10164	9654
4. Durban+	7396	7346	9364	8036
5. Thornville	7283	7584	6673	7180
6. Ichinga	7997	7162	7809	7656
7. Muguga	6616	7386	7123	7041
8. Monzi No. 2+	5780	6865	7410	6685
9. Baka	6774	8003	6869	7215
10. Phoka Court	6230	6703	6588	6507
11. No. 171 Star+	6540	6729	8284	7184
12. Coast Gross II+	8695	8413	9091	8733
13. No. 2 Star	6880	8656	9235	8257
14. Misuku	7472	6453	6399	6774
15. No. 161 Star+	7436	7454	6836	7242
16. Chilambula	6415	6058	6799	6424
17. Camper Down+	7785	8578	8744	8369
18. No. 343 Star+	8961	8326	8033	8440
19. S.E. Namwera	6593	6198	7863	6884
20. Thunda	6569	7513	7476	7186
21. Monsi No. 1+	6414	6924	8256	7198
22. Chinunkha	7216	8716	7840	7924
23. Meru	6171	5840	7060	6357
24. East Court B+	6698	7899	7954	7517
Means	7136	7497	7846

S.E. of Cultivars ± 623NS
S.E. of Nitrogen levels ± 141***
+ Introduced entries
Where *** is significance at P=0.001
NS is not significant.

Table 5. Forage DM yields (kg/ha) of Panicum strains across two replicates in response to cutting intervals.

Strains	3 weeks	6 weeks	9 weeks	Mean
1. Selection G	9939	9999	18211	12716
2. Ntchisi Panic+	9167	8848	13443	10486
3. Selection M	9022	7307	17133	11154
4. Selection J	7010	11033	22389	13477
5. Makueni Panic+	4852	6256	8485	6531
6. Selection X	4570	6607	6986	6054
7. Selection K	7948	9489	11671	9703
8. Selection D	7690	9287	16437	11138
9. Selection H	15723	16338	32473	21521
10. Selection O	10114	18105	22501	16907
11. Selection O	6696	10495	20981	12724
12. Selection I	7588	10924	16782	11764
13. Hamil Panic*	10592	14062	22776	15810
14. Chololo Panic	9329	17406	18039	14925
15. Selection B	8941	10076	15659	11559
Means	8614	11082	15597

S.E. of strains ± 1954**
S.E. of cutting intervals ± 825***
+ Local checks
Where

** is significance at P=0.01
*** is significance at P=0.001.

Table 6. Forage DM yields (kg/ha) of Panicum strains across two replicates in response to nitrogen fertilization levels.

Strains	N1 = 0 kg/ha	N2 = 40 kg/ha	N3 = 80 kg/ha	Mean
1. Selection O	9160	14889	14101	12716
2. Ntchisi Panic+	8979	11297	11182	10486
3. Selection M	8769	12184	12509	11154
4. Selection J	9117	15575	15739	13477
5. Makueni Panic+	4589	5569	9435	6531
6. Selection X	6368	5485	9435	6054
7. Selection K	8128	10382	6309	9703
8. Selection D	8506	11645	10598	11128
9. Selection H	14584	26342	13264	21521
10. Selection D	14592	15531	23688	16907
11. Selection O	10713	12561	17564	12724
12. Selection I	9890	13085	14900	11764
13. Hamil Panic*	12801	17070	13318	15810
14. Chololo Panic	12887	13622	15266	14925
15. Selection B	10755	12645	11276	11559
Means	9923	13392	13979

S.E. strains ± 195NS
S.E. Nitrogen levels
+ Local checks +825***
Where *** is significance at P=0.001
NS is not significant.

Conclusion

While the nitrogen fertilization regimes employed in this study were not aimed at coming up with a complete nitrogen response profile recommendation, it was important as a selection tool in demonstrating the necessity of considering low fertilizer input management. In the early evaluation stages it is important to appreciate materials that may not positively respond to high fertilization management as these have potential for eventual use in smallholder farming systems where inorganic nitrogen fertilizers may be lacking due to high cost.

The results show that the standard cultivars of star grass namely No. 2 star and Muguga and the three standard guinea grass cultivars, Ntchisi Panic, Hamil Panic and Makueni could be replaced by some more superior locally selected strains.

Phoka Court and Misuku star grass strains which have not demonstrated a response to high fertilization management were collected from sites characterised by acid infertile soils. The lack of positive response in these two and other similar strains could be an adaptation to these poor growing conditions. This potential ought to be exploited in greater detail.

This argument holds true also for the guinea grass strains that showed this potential.

Panicum maximum strains have shown variability that warrants selection to replace Ntchisi, Hamil and Makueni Panics by the more robust, leafier ecotypes.

References

Clayton, W.W. and Harlan, J.R. 1970. The genus Cynodon L.C. Rich in tropical Africa. Kew Bull. 24:185-189.

Harlan, J. R. 1970. Cynodon species for grazing and hay. Herb. Abstr. 40(3):233-238.

Harlan, J. R. and de Wet, J.M.J. 1969. Sources of variation in Cynodon dactylon (L.) pers. Crop Sci. 9:774-778.