COPING UP WITH CLIMATE CHANGE VARIABILITY THROUGH THE PRACTICE OF DIRECT SEEDING OF EARLY AHU RICE UNDER MEDIUM LAND SITUATION
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Date
2018-07
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AAU, Jorhat
Abstract
A field experiment entitled “Coping up with climate change variability through the
practice of direct seeding of early ahu rice under medium land situation” was carried out at
the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat during
2017 to developthe irrigation schedule of direct seeded early ahu rice under medium land
situation and to develop package of practices for direct seeded early ahu rice to suit the
variability in rainfall pattern covering the angle of nutrient management practices. The
experiment was laid out in a split plot design with 3 replications. The treatments consisted of
four irrigation regimes viz. irrigation at 80% available water till onset of pre-monsoon rain
(I1), irrigation at 70% available water till onset of pre-monsoon rain (I2), irrigation at 60%
available water till onset of pre-monsoon rain (I3) and rainfed (I4) as main plot and three
nutrient management treatmentsviz. full P as basal + ½ N and ½ K at 20 DAS + ½ N and ½ K
at 40 DAS (N1), full P as basal, 1/3 N and 1/3 K as basal + 1/3 N and 1/3 K at 20 DAS + 1/3 N and
1/3 K at 40 DAS (N2) and full P as basal, ½ N and ½ K as basal + ¼ N and ¼ K at 20 DAS +
¼ N and ¼ K at 40 DAS (N3) as sub plotand control (transplanted early ahu rice with
recommended water and fertilizer management practices). The soil of the experimental plot
was silt loam in texture having pH 5.2, organic carbon 7.2 g/kg, alkaline KMnO4 extractable
N 181.0 kg/ha, Brays-I P 10.7 kg/ha and 1 N ammonium acetate extractable K 227.9 kg/ha. It
contained soil moisture 27.6% at -0.03 MPa and 9.6 % at -1.5 MPa with bulk density of 1.34
g/cc. The rice variety “Inglongkiri” was sown on 18th February, 2017. The control treatment
with recommended water and nutrient management practice was transplanted on 17th March,
2017. The direct seeded crop was harvested on 15thJune, 2017 and the transplanted crop
(control) was harvested on 22nd June, 2017.
Experimental findings revealed thatirrigation at 80% available water till onset of pre
monsoon rain (I1) recorded the highest values for all the morphological and physiological
parameters along with the yield, yield attributing characters, nutrient (N,P and K) uptake and
water use efficiency (WUE) of the crop. The highest grain yield (39.83 q/ha) and straw yield
(90.96 q/ha) wererecorded atirrigation at 80% available water (I1). However, nutrient content
in soil after harvest of the crop was found to be non-significant. The highest uptake of
nitrogen (105.5 kg/ha), phosphorus (24.3 kg/ha) and potassium (124.2 kg/ha) were obtained
from irrigation at 80% available water (I1). However, nutrient content in soil after harvest of
the crop was found to be non-significant.
The highest values of all the morphological and physiological parameters along with
the yield, yield attributing characters, nutrient (N, P and K) uptake and water use efficiency
(WUE) of the crop were recorded under the nutrient management practice of full P as basal +
½ N and ½ K at 20 DAS + ½ N and ½ K at 40 DAS (N1). This treatment also recorded the
highest grain yield (34.16 q/ha) and straw yield (83.45 q/ha) and uptake of nitrogen (98.2
kg/ha), phosphorus (22.3 kg/ha) and potassium (115.6 kg/ha). However, nutrient content in
soil after harvest of the crop was found to be non-significant.
The experiment did not show any significant difference between direct seeded crop
and transplanted crop with respect to growth parameters, yield attributes and yield. However,
direct seeded rice recorded lower water use and higher WUE than transplanted crop. Direct
seeded crop also recorded the higher net return and benefit-cost ratio.