CHAPTER 5: The performance of Bambara groundnut landrace in controlled
5.2 Materials and methods
5.3.2 Emergence
Emergence varied significantly (P<0.001) over time (DAP), especially at 33/27˚C. There were highly significant differences (P<0.001) between temperature regimes with respect to emergence. Emergence was 90% higher at 33/27˚C compared with 21/15˚C. At 28 DAP, under 33/27˚C, JB, JR, TFB and TFR had obtained 100% emergence while at 21/15˚C maximum emergence was 70% for JR and JB. There was no observed trend on how provenances performed; however, there was a clear trend on seed colour performance. The dark coloured (red and brown) selections had higher emergence compared with light- brown selections. There were no significant differences (P>0.05) between water regimes with respect to emergence since all plants were established at 100%ETc. Landraces differed significantly (P<0.001) with respect to emergence. On average, the trend was such that JR (39.88) > TFB (38.39) > JB (37.80) > TFR (34.52) > TFLB (24.70) > JLB (19.94), respectively. The interaction between water and temperature regimes as well as landrace selections over time (DAP) was not significant (P>0.05).
Figure 5. 2: Final emergence of different bambara landraces grown under different temperature at different water levels (30% and 100% ETc). Note: JB = Jozini brown, JLB
= Jozini Light brown, JR= Jozini red, TFB= Tugela Ferry brown, TFLB= Tugela Ferry light brown and TFR= Tugela Ferry red.
0 20 40 60 80 100
JB JLB JR TFB TFLB TFR JB JLB JR TFB TFLB TFR
21/15˚C 33/27˚C
Emergence (%)
Temperature and landraces
LSD
(P=0.05)=44.21
30 ETc 100 ETc
128 Water regimes did not significantly differ (P>0.05) with respect to plant height (Figure 5.3). There were highly significant differences between landrace selections with respect to plant height, with dark coloured selections having taller plants than light-brown selections.
However, within provenances, there was no observed trend: Tugela Ferry and Jozini showed similar performance. The interaction between water regimes, temperature regimes, landrace selections and time (Weeks after planting; WAP) was not significant (P>0.05).
There were significant differences (P<0.001) with respect to plant height over time (WAP).
At 33/27˚C, plant height was shown to increase with time. Leaf number also performed similar to plant height (Figure 5.4). Bambara groundnut growth was shown to be more affected by temperature than water availability. Dark coloured selections were shown to perform better than light-brown selections.
Figure 5. 3: Plant height of Bambara groundnut landraces under different temperatures (A
= 21/15˚C and B = 33/27˚C) and at different water regimes (30% and 100% ETc). LSD (landraces)(P=0.05)= 20.97, LSD (WAP)(P=0.05)= 20.97, LSD (water regimes)(P=0.05)= 12.10 and LSD (temperature regimes)(P=0.05)= 12.10. Note: JB = Jozini brown, JLB = Jozini Light brown, JR= Jozini red, TFB= Tugela Ferry brown, TFLB= Tugela Ferry light brown and TFR= Tugela Ferry red.
129 Figure 5. 4: Leaf number of Bambara groundnut landraces under different temperatures (A
=21/15˚C and B=33/27˚C) and at different water regimes (30% and 100%ETc). LSD (landraces)(P=0.05)= 1.431, LSD (WAP)(P=0.05)= 1.431, LSD (water regimes)(P=0.05)= 0.826 and LSD (temperature regimes)(P=0.05)= 0.826. Note: JB = Jozini brown, JLB = Jozini Light brown, JR= Jozini red, TFB= Tugela Ferry brown, TFLB= Tugela Ferry light brown and TFR= Tugela Ferry red.
Chlorophyll content index (CCI) and stomatal conductance (SC) were only measured for 33/27˚C due to slow growth at 21/15˚C (Figure 5.5). There were no significant differences (P>0.05) between water regimes with respect to chlorophyll content index (Figure 5.5).
There were highly significant differences (P<0.001) between landrace selections; TFR (30.35) landrace selection had the highest CCI followed by JR (27.57) > TFB (24.13) >
TFLB (16.97) > JB (15.76) > JLB (12.33), respectively. On average, Tugela Ferry had higher CCI compared with Jozini provenance, and in each provenance the dark coloured selections were shown to have higher CCI compared with light-brown selections. The interaction between water regimes and landrace selections was significant (P<0.05).
Overall, with the exception of JB and TFR, CCI was higher at 100% ETc compared with 30% ETc. The interaction between water regime, landrace selections and time (WAP) was not significant (P>0.05).
130 Figure 5. 5: Effect of different water regimes (A = 100% ETc) and (B = 30% ETc) on chlorophyll content index (CCI) of bambara groundnut landrace selections. LSD (landraces)(P=0.05)= 5.581, LSD (WAP)(P=0.05)= 5.581, LSD (water regimes)(P=0.05)= 3.222 and LSD (temperature regimes)(P=0.05)= 3.222. Note: JB = Jozini brown, JLB = Jozini Light brown, JR= Jozini red, TFB= Tugela Ferry brown, TFLB= Tugela Ferry light brown and TFR= Tugela Ferry red.
Stomatal conductance was only measured at 33/27˚C; plant growth was very slow at 21/15˚C. Therefore, results of stomatal conductance only show the comparison between water regimes, landrace selection and time. There were highly significant differences (P<0.001) between water regimes (Figure 5.6); stomatal conductance was 29% higher at 100% ETc compared with at 30% ETc. There were highly significant differences between (P<0.001) landrace selections (Figure 5.6); stomatal conductance was higher in the TFR (144.8) landrace selection followed by JR (138.8) > TFB (105.5) > JB (86.5) > TFLB (58.6) > JLB (42.6), respectively. The Tugela Ferry provenance was shown to have higher stomatal conductance compared with the Jozini provenance. Dark coloured selections had higher stomatal conductance compared with light-brown selections under both water regimes (30% and 100% ETc). The interaction between water regimes, landrace selection and time (WAP) was not significant (P>0.05).
131 Figure 5. 6: Effect of different water regimes (A = 100%ETc) and (B = 30%ETc) on stomatal conductance of bambara groundnut landrace selections. Note: LSD (landraces)(P=0.05)= 38.29, LSD (WAP)(P=0.05)= 38.29, LSD (water regimes)(P=0.05)=
22.11 and LSD (temperature regimes)(P=0.05)= 22.11. JB = Jozini brown, JLB = Jozini Light brown, JR= Jozini red, TFB= Tugela Ferry brown, TFLB= Tugela Ferry light brown and TFR= Tugela Ferry red.