Nitrogen fertilization is one of the important factors affecting rice production and significant yield responses to applied N are obtained in nearly all lowland rice soil where irrigation is adequate and weed and pest problems do not limit growth. Exploitation of genotypic differences for enhancing utilization of soil and fertilizer nitrogen has also been one of the key issues in rice production. Genotypes may differ in their ability to take up soil nitrogen because of diverse plant characteristics.A field experiment was conducted during <italic>kharif season</italic> of 2001 at Agricultural Research Farm of SKUAST-J, R.S. Pura, Jammu to assess the nutrient uptake pattern of different varieties of rice under different nitrogen levels. The soil type of experimental field was clay loam in texture with almost neutral pH (7.0), medium in organic carbon (0.54%), low in available nitrogen (248 kg ha−1) and medium in available phosphorus (18.32 kg P2O5 ha−1), potash (212 kg K2O ha−1). The experiment was laid out in factorial RBD with three replications.The treatments included four levels of nitrogen (0, 50, 100 and 150 kg ha−1) and four varieties with two hybrids (PHB 71 and KRH 2) and two traditional varieties (PC 19 and Jaya). The seedlings of test varieties were transplanted at the age of 30 days at a spacing of 20 cm × 15 cm in the third week of July. Half nitrogen along with full phosphorus and potash was applied at transplanting and the remaining half of the N dose was applied in two splits at 30 and 60 days after transplanting, respectively. Plant samples were collected at tillering, flowering and harvesting stages to observe the nutrient uptake pattern. Nitrogen was determined by Kjeldahl's method, whereas phosphorus and potassium were estimated in tri-acid extract by vanadomolybdo-phospho-ric acid method and flame photometer, respectively (<xref ref-type="bibr" rid="bib001">1</xref>).<sec id="sec001"><title>Grain and straw yield

JRSKUASTJ

Journal of Research, SKUAST–J

0972-7469

Sher-E-Kashmir University of Agricultural Sciences and Technology, Jammu

jrskuastj-4-2-023

REPORT (R&D)

Effect of nitrogen and varieties on yield and nutrients uptake in rice

Kour

Sarabdeep

Sharma

R.K.

Bali

Amarjit.S.

Jalali

V.K.

Division of Soil Science and Agricultural Chemistry, SKUAST-J, Chatha, Jammu-18 0009

122005

42249252

Nitrogen fertilization is one of the important factors affecting rice production and significant yield responses to applied N are obtained in nearly all lowland rice soil where irrigation is adequate and weed and pest problems do not limit growth. Exploitation of genotypic differences for enhancing utilization of soil and fertilizer nitrogen has also been one of the key issues in rice production. Genotypes may differ in their ability to take up soil nitrogen because of diverse plant characteristics.A field experiment was conducted during <italic>kharif season</italic> of 2001 at Agricultural Research Farm of SKUAST-J, R.S. Pura, Jammu to assess the nutrient uptake pattern of different varieties of rice under different nitrogen levels. The soil type of experimental field was clay loam in texture with almost neutral pH (7.0), medium in organic carbon (0.54%), low in available nitrogen (248 kg ha−1) and medium in available phosphorus (18.32 kg P2O5 ha−1), potash (212 kg K2O ha−1). The experiment was laid out in factorial RBD with three replications.The treatments included four levels of nitrogen (0, 50, 100 and 150 kg ha−1) and four varieties with two hybrids (PHB 71 and KRH 2) and two traditional varieties (PC 19 and Jaya). The seedlings of test varieties were transplanted at the age of 30 days at a spacing of 20 cm × 15 cm in the third week of July. Half nitrogen along with full phosphorus and potash was applied at transplanting and the remaining half of the N dose was applied in two splits at 30 and 60 days after transplanting, respectively. Plant samples were collected at tillering, flowering and harvesting stages to observe the nutrient uptake pattern. Nitrogen was determined by Kjeldahl's method, whereas phosphorus and potassium were estimated in tri-acid extract by vanadomolybdo-phospho-ric acid method and flame photometer, respectively (<xref ref-type="bibr" rid="bib001">1</xref>).<sec id="sec001"><title>Grain and straw yield

Nitrogen application and varieties perceptibly influenced grain and straw yield of rice increased significantly with increasing levels of N application. The average increase due to 50, 100 and 150 Kg N/ha over no N was 32.1, 55.3 and 65.3 percent in grain and 32.6, 55.3 and 65.3 percent in straw yield, respectively (Table 1). Table 1

Effect of nitrogen on grain K straw yields and total N, P and K uptake in rice at harvest

Treatment	Yield q ha⁻¹		Total nutrient upake kg ha⁻¹

			N		P₂O₅		K₂O

	Grain	Straw	Grain	Straw	Grain	Straw	Grain	Straw

Nitrogen levels (kg ha⁻¹)
0	34.8	40.1	29.90	13.90	6.40	2.90	7.40	40.90
50	46.0	53.2	45.20	24.10	11.00	6.50	11.50	58.70
100	54.5	62.3	59.00	32.90	15.10	9.10	14.60	76.10
150	58.1	66.3	69.80	37.60	17.90	10.80	17.10	85.90
CD (P=0.05)	1.7	1.6	3.20	2.00	1.30	0.53	0.82	2.50
Varieties
PHB71	51.1	55.8	55.50	28.00	14.20	7.50	13.80	68.80
KRH2	55.6	61.6	63.50	34.20	17.00	9.20	15.40	79.50
PC 19	41.6	49.8	40.10	20.40	8.80	5.50	9.90	53.00
JAYA	45.1	54.7	44.90	25.90	10.40	7.00	11.50	60.30
CD (P=0.05)	1.7	1.6	3.20	2.00	1.30	0.53	0.82	2.50

Among the varieties, hybrid KRH-2 recorded highest grain and straw yields, whereas lowest yield was obtained from variety PC 19 (Table 1). Hybrids recorded more yield than the traditional varieties and this might be due to long growth durationas tested hybrids had longer productive periods than other tested varieties which may have helped in accumulation of photosynthates and thereby led to higher yields. The hybrid varieties had also comparatively bigger sink size and stiff stems than varieties Jaya and PC-19. Similar observations were recorded by (2).

Nutrient content

The concentration of nutrients (N, P and K) in rice plant at different stages of crop growth was greatly influenced by various treatments. The concentration of N, P and K was high at tillering stage and thereafter declined with the advancement in growth as also reported by (3). After crossing the tillering stage, the dilution effect may have caused decrease in nutrient concentration at advanced stages. Moreover, higher availability of nutrients as compared to dry matter production may also be the reason for higher nutrient content at early growth stages.

Amongst the various varieties, highest nutrient content was recorded in KRH 2 followed by PHB 71 and lowest nutrient content was recorded in variety PC 19 at all growth stages viz. tillering, flowering and harvesting stage. With increase in N levels from 0 to 150 kg ha⁻¹ nutrient concentration increased in all the varieties (Table 1).

Nutrient uptakeNitrogen-uptake

Irrespective of the varieties, increase in levels of N from 0 to 150 kg ha⁻¹ resulted in consistent increase in N-uptake at tillering, flowering and harvesting stages (Table 2). The percentage increase was from 72.6 to 206.9 percent at tillering and 63.3 to 193.5 percent at flowering stages. It may be due to improvement in N concentration and higher dry matter production that led to higher N uptake at higher levels of N. Our results confirm the findings of (4).

Among the varieties hybrid KRH 2 showed highest N-uptake at all the growth stages followed by another hybrid PHB 71, whereas the variety PC-19 recorded lowest N uptake (Table 1). It may be due to the reason that in the short duration varieties the rate of N uptake followed a simple sigmoidal curve whereas long duration varieties had two phases of uptake rate with one peak at maximum tillering and other at ear initiation stage as reported by (5). These results were also in agreement with findings of (6).

Phosphorus uptake

The main effect of N levels indicated that the total P-uptake at tillering, flowering and in grain and straw increased significantly with increasing levels of nitrogen from 0 to 150 kg ha⁻¹ (Table 1). This trend was observed in all the varieties under the influence of increasing levels of N. The increase in uptake of P may be due to P solubility and presumably increase in the root surface area. Among varieties, hybrid KRH 2 recorded highest P uptake at tillering, flowering and harvesting stages with a magni-tude of superiority of 8.5, 46.1 and 35.7 percent at tillering and 2.5, 39.6 and 32.7 percent at flowering over PHB 71, PC-19 and Jaya, respectively.

Potassium uptake

Main effects revealed that total uptake of K at tillering, flowering and in grain and straw also got increased consistently and significantly with increasing rates of N upto 150 kg ha⁻¹. This may be ascribed due to better root and shoot growth and concentration of K in shoot inspite of dry matter accumulation. Moreover, N application favours the translocation of all the three nutrients from root to shoot. Similar results were reported by (6).

Amongst varieties, KRH 2 recorded maximum K uptake at tillering, flowering and harvesting stages than over PHB 71, PC 19 and Jaya, respectively. Production of higher dry matter by hybrid KRH 2 may be the reason for higher K-uptake (Table 1).

The study revealed that owing to higher nutrient uptake with the increase in N application proved helpful for harvesting higher yield from hybrid rice variety KRH 2 under sub-tropical conditions of Jammu.

References1

Jackson

M.L.

1973. Soil chemical analysis.Prentice Hall of Inc.Englwood cliffs New Jersy, USA.2

Om Hari

Katyal

K.S.

Dhiman

D.S.

1997. Effect of nitrogen and seed rate in nursery on growth and yield of hybrid Rice. Indian J. Agron.42: 275–277.3

Tanaka

Patnaik

Abichandani

C.T.

1959. Studies on nutrition of rice plant III. Partial efficiency of nitrogen absorbed by rice plant at different stages of growth in relation to yield of rice. Proc. Indian Acad. Sci. Soc.49: 207–216.4

Pandey

Agarwal

M.M.

1991. Influence of fertility levels, varieties and transplanting time on rice. Indian J. Agron.36: 459–463.5

Mehrotra

O.N.

Sinha

N.S.

Srivastava

R.D.L.

1968. Studies on nutrition of Indian cereals2. Uptake of nitrogen and phosphorus at different stages of growth by early paddy (unhulled rice) under varying fertilizer management. Plant soil28: 422–30.6

Sarkar

P.K.

Debnath

N.C.

1996. Effect of variable levels of nitrogen on uptake of nutrients by different varieties of rice in an alluvial soil. Indian Agric.40: 79–87.