Sesame is grown as rice-fallow crop during Summer season with the use of residual
moisture and nutrients of pervious season (Rabi) rice crop. Hence, no
fertilizers are applied to the sesame crop, which is also a nitrogen responsive
crop. The response of sesame to N fertilizer varies from 20-150 kg ha-1
as per the report of Hemalatha et al. (1999). This sesame crop may utilize
the native soil N also for its growth and development. This may affect the nutrient
uptake by the next season crops. If rice crop is grown in the following season,
it may suffer to extract nutrients from the soil because of nutrient removal
by sesame and also leads to fixation of applied inorganic nutrients. Rice is
also a nutrient responsive crop, which is the maximum consumer of N fertilizer
constituting one third of the total N consumption of the world (Saravana Pandian
and Rani Perumal, 2002). Thus, N is the most critical input that limits rice
productivity and increasing rice productivity would mean more supply of N to
the crop. Increasing the rice productivity per unit area by the use of appropriate
agronomic management practices has become an essential component of rice production
technology (Sridevi et al., 2006). Lowland rice depends more on soil
fertility than on fertilizers. The dependence of lowland rice on soil fertility
is best illustrated by a Japanese saying Grow paddy with soil fertility,
Grow barley with fertilizers (Yoshida, 1981). Since both are nutrient
responsive crops, the sesame crop grown in the previous season may affect the
growth and development of rice crop. This impact of growing sesame in previous
season on dry matter production, nutrient uptake and yield of rice crop was
studied in this experiment.
MATERIALS AND METHODS
Experimental Design and Treatment Details
The experiment was conducted in a loamy sand soil of Pandit Jawaharlal Nehru
College of Agriculture and Research Institute, Karaikal, Union Territory of
Pondicherry, India during the year 2004-05. The experimental site is situated
12 km from Bay of Bengal, lies between 10o 49' and 11o
01' North latitude and 78o 43' and 79o 52' East longitude
with an altitude of 4 m above Mean Sea Level (MSL). The initial soil analyses
showed that the soil was loamy sand in texture falls in Fluventic haplustept
taxonomic class. The soil is optimum in bulk density (1.33 mg m-3)
and particle density (2.66 mg m-3) with the porosity of 50%. The
soil reaction was neutral (pH: 7.61) and the electrical conductivity is low
(0.21 dS m-1). The soil was low in organic carbon content (0.32%)
and available nitrogen (KMnO4-N: 213 kg ha-1), medium
in available potassium (NH4OAc-K: 262 kg ha-1) and high
in available phosphorous (Olsen-P: 31.4 kg ha-1). The experiment
was conducted in FRBD design with three replications. The treatmental details
are given in Table 1.
The field was divided in 60 equal plots of 20 m2. The experiment was carried out in two consecutive seasons. In the Summer season (Chithirai pattam), the 30 plots of the field was raised with sesame and the other plots were kept fallow. The sesame crop was cultivated with residual nutrients of previous season (Rabi) rice crop without any artificial means of supply and harvested. In the Kharif season, the left out sesame stubbles of about 15-20 cm height were incorporated 15 days before transplanting. Rice crop was raised in all the 60 plots of two different situations viz., with sesame as previous crop (situation I) and without sesame as pervious crop (situation II) with two cultivars viz., a medium duration variety of ADT 38 and a long duration pre-release culture of KR 99001 with five levels of nitrogen viz., 0, 50, 100, 150 and 200 kg N ha-1. The treatment details are given in Table 1. The nitrogen (N) was supplied through urea in four equal splits as basal, at active tillering, panicle initiation and grain filling stages as per the treatment levels. Phosphorous (P) (@ 50 kg ha-1) was supplied through single super phosphate in two equal splits as basal and at active tillering stage; potassium (K) (@ 50 kg ha-1) through muriate of potash in four equal splits as that of N and zinc through zinc sulphate (@ 12.5 kg ha-1) as basal. A hand weeding was done at 25 days after transplanting to remove the competitive weeds in the field. A pesticide spray of monocrotophos @ 250 mL ha-1 was given at 30 days after transplanting to control leaf folders. The DMP was recorded at Active Tillering (AT) stage and Panicle Initiation (PI) stage. The plant samples were analyzed for nutrient content and multiplying with DMP the nutrient uptake was calculated. The crop was harvested separately from the plots, harvested and winnowed and grain and straw yields were recorded. The observations collected from the field experiment and the data of analyses of soil and plant samples were subjected to statistical scrutiny as per the procedure of Gomez and Gomez (1984).
|| Treatment details of rice varieties (V) under varying field
conditions (S) with nitrogen levels (N)
Optimization of N Requirement
The data on the grain yield of rice under various treatments were fitted
into the appropriate response function following statistical procedures. In
case where the response function was quadratic type, the physical optimum dose
of N was calculated by equating the first order derivative of the [dy/dx = 0]
response function to zero,
The economic optimum dose was calculated by equating the first order derivative
of the response function to the rice ratio (px/py) i.e.,
taking into account the unit cost of N kg-1 as 10.4 and price of rice grain as Rs. 5 kg-1.
RESULTS AND DISCUSSION
Dry Matter Production
At AT, the DMP was found to be higher in situation II over situation I in
both the varieties (Table 2). This might be due to the removal
of nutrients by sesame crop, which is also N responsive crop as reported by
Praveen Rao et al. (1994), might cause initial set back in supply of
nutrients to the crop. Higher levels of N produced higher DMP at this stage.
At PI, unlike at AT, the performance rice varieties were not influenced between
the situations. This shows that the crop would have received nutrients from
decomposed stubbles of sesame at later stage in situation I. The combination
of organic and inorganic N in situation I and the normal supply of nutrients
in situation II resulted in better performance of rice crop in both the situations.
This kind of results was obtained by Omar Hattab et al. (1998) and Priyadarsini
and Prasad (2003). In both the situations increasing N levels increased the
DMP. This is obvious and in line with the findings of Srinivasalu Reddy (1998)
and Somasundaram et al. (2002).
The variation in the field conditions due to the situations did not bring
significant variation in grain yield, but slightly higher yield was noticed
in situation II over situation I (Table 2). This might be
due to the reason that the incorporated stubbles of sesame in field might have
released the immobilized N in the later stages and supported the crop growth
|| DMP, grain and straw yield and N uptake by rice varieties
under different soil conditions
|S1: Situation 1; S2: Situation 2; NS:
The slight variation might be due to the differential supply of nutrients in
the initial stages of crop growth, wherein the nutrient supply was low in situation
I, caused by uptake of nutrients by sesame crop.
Optimization of Nitrogen Requirement
In the case of medium duration variety ADT 38, the physical optimum was
with 157 kg N ha-1 and economic optimum was with 133 kg N ha-1.
The pre-release culture KR 99001 showed its physical optimum with 131 kg N ha-1
and economic optimum with 114 kg N ha-1. Both medium duration variety
ADT 38 and long duration pre-release culture KR 99001 manifested higher yields
at 150 kg N ha-1 in both the situations. This revealed the fact that
this level of N, which is a recommended dose of N for medium and long duration
rice crop, is capable of supplying nutrients to the demand of the crop at appropriate
stages both by direct supply of nutrients and by indirect supply through mineralization
of sesame stubbles. This kind of result that is the combination of organic and
inorganic sources of N in enhancing the yield finds support from Wopereis
et al. (1994), Saravana Pandian and Rani Perumal (1994) and Omar Hattab
et al. (2000).
The straw yield was not significantly influenced by the situations studied
(Table 2). This might be due to late recovery of rice from
the impact of nutrient loss caused by the sesame crop in the previous season
in situation I. The immobilized N by the sesame stubbles would have been released
in the later stages. The beneficial effect of mineralization of nutrients from
the crop residues was well established by Omar Hattab et al. (1998),
Singh et al. (1997), Grace et al. (1999), Deka Medhi and Medhi
(2000) and Rajni Rani and Srivastava (2001).
Nitrogen Uptake at Active Tillering Stage
There was no significant difference in N uptake under the situations studied
(Table 2). Each N level performed similarly under both the
situations. The reason might be that the accumulation of N in crop at initial
stages would be low and be satisfied by the situations and N levels. This is
in agreement with the findings of Palaniappan and Siddeswaran (1994), who had
witnessed no variations in the N uptake by rice crop at initial stages of crop
growth due to different N levels.
Nitrogen Uptake at Panicle Initiation Stage
The same trend as that of AT was noticed here also, but the uptake values
were found to be high as compared to active tillering stage. In general, increasing
N levels increased the crop N uptake. This was also experienced by Palaniappan
and Siddeswaran (1994) and Hussain (1999).
Nitrogen Uptake by Straw
The N uptake by straw was found to be significantly higher in situation
II than in situation I. This was well established in long duration KR 99001,
but not in medium duration ADT 38. The variation might be due to higher need
of N from panicle initiation stage for long duration variety as reported by
Sivasamy et al. (1994), who observed the maximum rate of N uptake from
urea during panicle initiation stage to first flowering phase in long duration
Nitrogen Uptake by Grain
The N uptake by seeds was not significantly influenced by the situations.
Each N level performed similarly under both the situations. The N levels increased
the N uptake but not significantly. The N uptake by grains was found to be low
in control, which is quite expected.
Phosphorus Uptake at Active Tillering Stage
The P uptake was found to be significantly higher in situation II, where
the dry matter production was higher over situation I and accordingly manifested
higher P uptake (Table 3). The higher uptake of P by medium
duration variety ADT 38 in situation II was with 200, 150 and 100 kg N ha-1,
but in situation I, it was only with 200 kg N ha-1, revealing the
need of N in situation I for P uptake. This might be due to the reason that
in situation I the biomass production was high only with 200 kg N ha-1.
This possible correlation of N supply with P uptake was pronounced from the
findings of Omar Hattab et al. (2000).
Phosphorus Uptake at Panicle Initiation Stage
The P uptake was not influenced by the situations studied and N levels compared.
This might be due to the reason that at this stage of crop, equal amount of
dry matter was produced by both the situations. Increasing N levels increased
the P uptake, which was also observed by Omar Hattab et al. (2000).
Phosphorus Uptake by Straw
The P uptake of straw was found to be higher in situation II than in situation
I. The higher straw yield under situation II resulted in higher P accumulation
in straw. Increasing N levels increased the P uptake due to higher DMP. With
150 kg N ha-1, the situation II recorded higher P uptake by producing
more biomass than in situation I.
|| P and K uptake by rice varieties under different soil conditions
|NS: Non Significant; S1: Situation 1; S2:
Phosphorus Uptake by Grain
There was no significant variation in P uptake by grain under different
situations. The uptake was found to be increased with increased N levels for
both the varieties under both the situations, but the increase was not to a
greater extent. This slight variation might be due to the variations in grain
yield owing to N levels.
Potassium Uptake at Active Tillering Stage
The uptake of K was not significantly influenced by the situations studied
(Table 3). Each N level also performed equally between the
situations. This might be due to the reason that the ability of the soils of
both the situations to supply enough K by direct inorganic source in situation
II and by combination of organic and inorganic source in situation I (Priyadarshini
and Prasad, 2003).
Potassium Uptake at Panicle Initiation Stage
The situations did not create any variation in the K uptake. But, the highest
dose of N i.e., 200 kg N ha-1 recorded significantly higher uptake
of K in situation II over situation I. Again this result could be the reflection
Potassium Uptake by Straw
The K uptake was found to be significantly higher in situation II than in situation
I, might be due to the higher straw yield and the K is consumed luxurily by
the crop, the straw in situation II showed higher values for K uptake.
Potassium Uptake by Grain
The accumulation of potassium in grain was not significantly varied with
the situations. The performances of both each variety and N level were comparable
under both the situations.
The sesame crop grown in previous season with residual moisture and nutrients of Rabi rice crop has no profound effect on next season rice crop. The DMP was initially low in situation I but managed in later stages. The N and K uptake at AT was equal under both the conditions but P uptake was high in situation II, because initial fixation of P in the soil. The nutrient uptake at PI stage was comparable in both the situations by the recovery of nutrient from inorganic and organic supply. Thu nutrient uptake by grain was comparable in both the situations owing to genetic nature. The uptake by straw was high in situation II, due to high biomass and luxurious consumption of potassium. The optimization procedure reveals that the recommended dose of N i.e., 150 kg N ha-1 will be sufficient for better growth and development. The nutrient uptake and yield of rice crop were not significantly influenced by the previous season sesame crop. The sesame crop grown in previous season did not affect the nutrient uptake and yield of succeeding rice crop.