Integrated management of perennial wild rices in lowland irrigated rice
| dc.contributor.author | Mkocha, Magdalene Nelson Enock | |
| dc.date.accessioned | 2026-05-13T13:49:51Z | |
| dc.date.available | 2026-05-13T13:49:51Z | |
| dc.date.issued | 1999 | |
| dc.description | Dissertation | |
| dc.description.abstract | Two field experiments were conducted during the season 1997/98 at Kapunga Rice Irrigation Project (KRIP) in Mbeya region to determine the influence of perennial wild rices on rice yields and to evaluate effectiveness of ploughing depths, hand weeding, herbicides and seeding rates in the control of the wild rices and other weeds. Experiment 1 was a split plot in a randomized complete block design with three replications. Ploughing depths (10, 15, 20, and 25 cm) constituted the main plots while the seeding rates (110, 130, 150, 170 kg ha'1) were the subplots. Pregerminated IR 54 paddy seeds were sown on 13 Februaiy 1998. Data collected included wild rice fresh and dry biomass before and after treatments, plant height at booting and at maturity, number of tillers, and panicles per plant and per square metre, number of grains per panicle, percentage ripened grains and grain yield per hectare. Combinations of 15 cm x 170 kg ha'1 (ploughing depth x seeding rates) recorded the highest grain yield of 4852.0 kg ha'1 which was significantly (P <applied at the rate of 5.4 kg a.i ha'1 reduced wild rices density by 91%, other weeds by 65% compared to the unweeded check., 0.05) different from other treatment combinations. Lowest rhizome fresh and dry biomass of 17.0 and 4.9 g m'2 respectively, were recorded in the same treatment combinations signifying better effectiveness in reducing wild rice biomass than other treatments. The high grain yields were attributed to high number of panicles per square metre, high percentage ripened grains, number of grains per panicle and larger grain size than other treatments as a result of reduced wild rice biomass per square metre. Experiment 2 was laid out in a randomized complete block design replicated three times. There were ten treatments comprising of hand weeding treatments and combinations of herbicides (glyphosate or whip super) with hand weedings and an unweeded check. The different weed control practices applied had significant (P< 0.05) effects on there duction of rhizomatous wild rices and other weeds' density. Two hand weedings reduced the density of wild rices by 73% and other weeds by 72% while glyphosate applied at the rate of 5.4 kg a.i ha'1 reduced wild rices density by 91%, other weeds by 65% compared to the unweeded check. Plots hand weeded twice recorded the highest grain yield of 1648.4 kg ha'1 which differed significantly (P < 0.05) from all other treatments. Plots treated with glyphosate at 5.4 kg a.i ha'1 which had the highest reduction in wild rice density, recorded a grain yield of 1456.1 kg ha'1. The lowest grain yield was recorded in plots treated with whip super at the rate of 20 g a.i ha'1, this low grain yields in whip super treatments may be due to its being less effective in reducing wild rice density than to two hand weedings or glyphosate and its toxic effects on rice plants. Grain yield was significantly and positively correlated with percentage effective tillers, number of grains per panicle, percentage ripened grains, number of panicles per square metre, and 1000 grain weight. Negative correlations were obtained between grain yield per hectare and wild rice shoot fresh biomass and weed densities per square metre showing that the weeds had significant negative effects on grain yield. Economic analyses revealed that all weed control practices were significantly beneficial, the highest net benefits being Tanzanian shillings (Tshs.) 307 859.27 ha'1 for the plots hand weeded twice. It is therefore evident that hand labour is beneficial but since labour availability is not guaranteed, this may limit large scale rice production reliance on it. Manual labour can therefore be utilized by small scale producers while large scale producers can use glyphosate for wild rice control. | |
| dc.description.sponsorship | Canadian International Development Agency (CIDA) through the Directorate of Training Fund for Tanzanian Women (TFTW) of the Ministry of Community Development, Women Affairs and Children | |
| dc.identifier.uri | https://www.suaire.sua.ac.tz/handle/20.500.14820/7567 | |
| dc.language.iso | en | |
| dc.publisher | Sokoine University of Agriculture | |
| dc.subject | Wild rices | |
| dc.subject | Irrigated rice | |
| dc.subject | Lowland | |
| dc.subject | Hand weeding | |
| dc.subject | Seeding rates | |
| dc.title | Integrated management of perennial wild rices in lowland irrigated rice | |
| dc.type | Thesis |