The evaluation, crop management and economic potential of diverse of guar accessions for Limpopo Province, South Africa

Abstract

Guar bean (Cyamopsis tetragonoloba L. Taub) is a drought tolerant leguminous crop usually grown for its seed which has a special gum (galactomannan) used in the food and the mining industries. The study aimed at evaluation of yield potential and agronomic management of 14 determinate and indeterminate guar accession lines sourced from the Australian Tropical Crops and Forages collection grown under dry-land conditions of Limpopo province and assessing their response to phosphorus and inoculation. Two different experiments, one on variety evaluation and the other on response to P fertilizer and inoculation were conducted during 2006/7 and 2007/8 growing seasons at Syferkuil and Tompi Seleka in the Limpopo Province, South Africa. There were significant differences amongst the 14 guar accession lines at Syferkuil during 2006/7 and 2007/8 and Tompi Seleka during 2007/8 growing seasons. Tompi Seleka showed higher potential for guar bean production over Syferkuil on the basis of grain yield. Seed yield from the two locations during the two seasons ranged from 326 kg ha-1 by variety Stonewall to 2340 kg ha-1 by variety Durgapurasaffed. At Syferkuil in 2006/7 Brooks variety recorded the highest seed yield of 1103 kg ha-1 while Hall achieved lowest seed yield of 353 kg ha-1. During 2007/8 at Syferkuil, TRCF 95203 recorded the highest seed yield of 701 kg ha-1 and Stonewall recorded lowest of 326 kg ha-1. At Tompi Seleka in the same season, the highest yield was recorded with Durgpurasaffed variety that recorded 2340 kg ha-1 and lowest Stonewall with 720 kg ha-1. The varieties which consistently performed well and were within the top five performing lines at the two locations were Durgapurasaffed, TRCF CSIRO and Brooks. The accession lines at Tompi Seleka experiment gave higher dry matter and seed yields than at Syferkuil, suggesting their preference for hot environments. In the second experiment, the response of two guar bean varieties to phosphorus level and inoculation was evaluated. Variety did not influence seed yield. Application of phosphorus (P) at 60 kg ha-1 plus inoculation significantly increased seed yield. At Tompi Seleka 2007/8 season, 60 kg ha-1 of P application achieved seed yield 37% higher than the control treatment. In the same season at Syferkuil the highest seed yield was also recorded at 60 kg ha-1 P application and was 57% xiii more than lowest seed yield from the control treatment. Grain yield significantly increased during 2006/7 as influenced by P application rate of 30 kg ha-1 compared to zero P fertilizer while there was no significant different between P rates during 2007/8 season at this site. The results from the study showed good response P application in the range of 30 to 60 kg ha-1. Inoculation significantly increased seed and dry matter yield at all sites. Variety X P levels and variety X inoculation interactions significantly influenced seed yield and dry matter at all sites. Both varieties achieved the highest seed yield at 60 kg ha-1 and the lowest was with the control at Syferkuil for both varieties. At Tompi Seleka, the control and application 30 kg ha-1 of fertilizer gave similar seed yield for both varieties. At Syferkuil in 2006/7 and Tompi Seleka in 2007/8 both Stonewall and Cedric were higher with inoculation but in 2007/8 Cedric had lower seed yield with inoculation at Syferkuil. The Phosphorus X inoculation interaction was significant with combination of 60 kg P ha-1 and inoculation giving significantly higher seed yield than the 0 kg P ha-1 and no inoculation. Future experiments should consider inclusion test in these guar accession under dryland conditions, levels of P higher than 60 kg P ha-1, include nodulation data, quality evaluation of guar seed and conducting basic growth margin analysis on P and inoculation of guar.