Abstract:

The popular upland rice varieties currently grown in Uganda are from interspecific
crosses of African rice species Oryza glaberrima and Asian rice Oryza sativa called the
'New Rice for Africa' (NERICA). They are resistant to major biological constraints, but
show differential sensitivity to drought stress and have low aroma trait, which are the
major concerns of the Ugandan farmers. Area under rice production can increase and
local production can meet market demands if materials availed to farmers have preferred
traits such as aroma and tolerance to drought. This report focuses on work conducted
between the period 2004 and 2006, although bulking and evaluation of seed started in
2003, with the aim of testing for adaptation, and selecting for drought tolerance and
aromatic trait. First, on-station screening and multiplication of introductions was
conducted at the National Crops Resources Research Institute, Namulonge (NaCCRI).
Secondly, performance of promising materials was tested in multi-locations using
participatory approaches. Thirdly, grain quality traits were assessed with various
stakeholders. The fourth activity was to determine appropriate plant density and fertilizer
rates for the selected varieties. The fifth activity was screening and identification of
suitable herbicides for upland rice cultivation. Evaluation of the introductions was done
in partnership with farmers in four main districts namely Masindi, Iganga, Luweero and
Wakiso.
The introductions that were evaluated came from two main sources namely; the Africa
Rice Centre-West African Rice Development Association, (ARC-WARDA) and the
National Program of Madagascar (FOFIFA). The varieties from ARC-WARDA were
exclusively NERICA and performed better than those from FOFIFA, which tended to be
late maturing and would end up being caught by drought at the time of flowering and
grain filling. Varieties which attained 50% heading in 70 days or less, gave better yields
and two of these are NERICA 1 and NERICA 10 with 70 and 69 days, respectively.
Other varieties including NERICA's 15, 17 and 18 were late maturing and gave lower
yields. Although NERICA 14 was comparatively early maturing, it is however very
susceptible to neck and leaf blast, to the extent that no harvests were made in most evaluations. Similarly, NERICA's 15, 17, and 18 had red rice grains, a trait not preferred
by farmers/consumers in the country. On the other hand, the FOFIFA materials had very
long maturity periods. From the evaluations made, NERICA 1 and 10 were the most
preferred mainly because of earliness, stable high yield and the former is also aromatic, a
characteristic some farmers crave for. It is important to point out that, testing for
adaptability and releasing finished product from other sources is just a short term
measure to meet increasing demands from farmers. Therefore systematic breeding work
to improve local varieties and even develop new ones is on-going for both lowland and
upland ecologies. The two varieties, NERICA I and NERICA 10 were presented to the
Variety Release Committee and released in 2007. The original names of the two varieties
as given from source of development were maintained to avoid confusion as was the case
with NERICA 4, which in 2002 was released as NARIC 3 in Uganda yet it continues to
be called its original name of NERICA 4. This nomenclature has also been maintained in
other African countries, a position which has been universally accepted.
In the study to investigate the performance of upland rice under different fertilizer levels,
five varieties were evaluated under four nitrogen levels thus; ON, 40N, 80N and 120N.
There was significant response of upland rice varieties to application of nitrogen
fertilizer. Increase in N level increased yield of rice significantly with the highest grain
yield recorded under 80 Kg N/ha. NERICA 4 had the best response to nitrogen fertilizer,
especially, under mild water stress. Application of nitrogen also increased tiller
production, plant height, panicles/m2 and grains/panicle. The results suggested the need
to investigate nitrogen use efficiency of rice cultivars under water stress and their
potential in nitrogen recovery after stress.
A trial involving Nitrogen, Phosphorus and Potassium (NPK), resulted in significant
increase in grain yield of NARIC 3, from 1.47 tons/ha without NPK fertilization to 8.02
tons/ha with 120:20:40 combination. Potassium fertilization had little effect on total grain
yield. The levels of potassium in the soil may have been sufficient and this precluded any
effect of the applied potassium on grain yield. In addition, planting rice varieties at different seed rates and applying varying levels of nitrogen had a significant effect on the number of tillers that survived to form panicles. The seed rate of 90 kg per hectare gave
the highest number of panicles and subsequently higher yields. It had the highest number
of grains per panicle and total number of tillers. There were similarities among the rest of
the seed rates in most characters. In terms of fertilizer rates, the 80 KgN/ha application
significantly increased rice yields. A high nitrogen level 120kgN/ha increased the number
of tillers and panicles per unit area but had no effect on the length of the panicle.
Several herbicides tested had a good control of the broad leaf weeds and very little
control of grasses. The results obtained indicate that Satunil was the best herbicide
followed by Butanil-70, which is a combination of propanil and butachlor. The nut sedge
was not controlled by a single herbicide, but a combination of Butanil-S and 0.3 kg of
2,4-D showed some level of control. The numbers of herbicides recommended for use in
rice production are however, limited. There is a need to access more herbicides, which
should be channelled through research directly instead of research working with the ones
available on the market as has been the case. There is also a need for government
intervention to ensure that the recommended herbicides are always on market.
Tremendous success has been achieved through training of farmers in rice management
practices. Farmers have been trained on practices like recommended spacing, seeding
depth, fertilizer application, weed management and harvest and post harvest processing.
Some farmers' associations that are involved in seed production have been exposed to
seed production technologies through training. More farmer groups interested in seed
production are emerging and this suggests that a good source of breeder and foundation seed needs to be established.