CLIMATE RESILIENT NITROGEN MANAGEMENT TO ENHANCE THE PRODUCTIVITY OF LATE SOWN SHORT DURATION RICE VARIETIES
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Date
2023-11-15
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Acharya N G Ranga Agricultural University
Abstract
A field experiment entitled “Climate resilient nitrogen management to enhance the productivity of late sown short duration rice varieties” was conducted during kharif, 2021 in clay loam soils of research farm of ICAR-Indian Institute of Rice Research located at Rajendranagar, Hyderabad. The objective of the experiment was to study the performance of short duration rice varieties under late sown conditions, to find out the best climate resilient nitrogen management practices and to calculate the energy use efficiency and economics of late sown rice cultivation. The soil of the experimental plot was low in available N, P and K with pH 7.4. Twenty one days seedlings were uprooted and transplanted in main field on 25th August 2021. The experiment was laid out in a split plot design with three replications. Main plots consisted of three short duration rice varieties (DRR Dhan-44, MTU 1010 and MTU 1156) and sub plots comprised of four nitrogen management practices viz; (recommended dose of nitrogen (RDN) @ 120 kg N ha-1, silicon coated slow release urea (SCSRU) @ 90 kg N ha-1, Leaf Colour Chart (LCC) @ 105 kg N ha-1 and soil test crop response (STCR) @ 114.5 kg N ha-1). The duration of all three varieties is 120 days (short duration). Recommended dose of N-P2O5-K2O was 120-60-40 kg per hectare. Recommended dose of nitrogen (120 kg ha-1) was applied through urea in three equal splits at basal, active tillering and panicle initiation stages. Silicon coated slow release urea was developed in laboratory of ICAR-IIRR and applied @ 75% of RDN (90 kg ha-1) in equal three splits. Whenever, the LCC values were found to be below the fixed critical level of three, the recommended quantity of nitrogen was applied @ 25 kg ha-1 and the basal dose of nitrogen was applied at 30 kg ha-1. In LCC based nitrogen management total 105 kg N ha-1 was applied in 4 splits. The fertilizer prescription equation to attain specific yield targets based on soil
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available nutrient levels for the experimental field was FN = 42 T - 0.55 SN. The targeted yield was 6 t ha-1. Accordingly the nitrogen dose was 114.5 kg ha-1. The crop was received was grown under irrigated condition. The crop received total precipitation of 473 mm during the crop growth period. Total input and output energy was calculated by multiplying the energy coefficient of the respective input or output with the quantity of the particular input or output. Other package of practices and plant protection measures were followed as per the state recommendation.
The results of the experimental trial revealed that among the varieties, growth parameters viz., dry matter production, number of tillers m-2 and leaf area index of rice were recorded the highest in MTU 1156 variety. The highest plant height was found in DRR Dhan 44. The lowest were recorded in MTU 1010. With regard to nitrogen management practices, at all stages of observation (except at active tillering), growth parameters obtained were highest with application of LCC based N application 105 kg N ha-1, however, on par with RDN @ 120 kg N ha-1 and followed by STCR based N application 114.5 kg N ha-1. The lowest growth parameters (dry matter production, number of tillers m-2 and leaf area index) were recorded in the plots applied with silicon coated urea @ 90 kg N ha-1 while the interaction effect these two factors on growth parameters was non-significant.
Regarding yield attributes, productive tillers m-2, panicle length, panicle weight, total number of grains per panicle, filled grains per panicle and test weight were found to be the highest with the MTU 1156 variety (M3), which performed superior over rest of the varieties. MTU 1010 (M2) recorded with the lowest yield attributes. Among the nitrogen management practices, LCC based nitrogen application @ 105 kg N ha-1 resulted in the highest yield attributes over other treatments, however, on par with RDN @ 120 kg N ha-1 and in turn this on par with STCR based nitrogen application 114.5 kg N ha-1. The lowest yield attributes were recorded in the plots applied with silicon coated urea @ 90 kg N ha-1. The test weight of rice among the varieties was significant, however, among nitrogen management practices was found to be non-significant. Panicle length and panicle weight did not differ significantly among N management practices.
The highest grain (5707 kg ha-1) and straw yield (7102 kg ha-1) of rice were obtained with MTU 1156 (M3) and the lowest was and kg ha-1 in MTU 1010 (M2). Among N management practices, application of N @ 105 kg ha-1 based on LCC reading 3 resulted in the highest grain (5758 kg ha-1) and straw yield (7112 kg ha-1), however, on par with RDN @ 120 kg N ha-1 in turn on par with STCR based N application 114.5 kg N ha-1. The lowest grain and straw yield and kg ha-1 were recorded in silicon coated urea @ 90 kg N ha-1 applied plots. Harvest index was found to be similar among the varieties and N management practices.
Significantly superior quality parameters (head rice recovery, milling, hulling percentage and amylose content) were found in MTU 1156 (M3). Application of 105 kg N ha-1 based on LCC reading 3 resulted in the highest head rice recovery, milling, hulling percentage, and amylose content. MTU 1156 recorded highest uptake of nitrogen at panicle initiation, flowering and harvest stages. Similarly, among N management practices, LCC based N application 105 kg ha-1 resulted in the highest uptake by rice crop at panicle initiation, flowering and harvest stages. Similar trend was also found with regard to P and K uptake also. Post-harvest soil available nitrogen was the highest in MTU 1156 grown plots (245.7 kg ha-1). Among N management practices, application of LCC based N @ 105 kg ha-1 resulted in the
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highest soil available N in the plots (248.5 kg ha-1), however, on par with that of RDN @ 120 kg N ha-1 (242.6 kg ha-1). Similar trend was also found with regard to post harvest soil available P status, while, post harvest soil available K was not affected either by different varieties or N management practices. post harvest soil nutrient status revealed that there was a loss of soil available nitrogen compared to initial status. However, there was a gain in case of soil available P and K.
Significantly highest gross returns (Rs.1,25,494 ha-1), net returns (Rs. 90,944 ha-1), and B-C ratio (2.63) were found with variety MTU 1156 (M3), over rest of the varieties. Among N management practices, the highest economic returns (B:C ratio of 2.66) were obtained with the application of N @ 105 kg ha-1 based on LCC reading 3. MTU 1156 and application of N @ 105 kg ha-1 based on LCC reading 3 was found to be the highest energy efficient variety and N management practices, for rice cultivation.
Hence, it can be concluded that variety MTU 1156 and application of N @ 105 kg ha-1 were found to be the best for achieving higher grain yield, net returns and energy use efficiency under late sown conditions, and could be recommended in the late sown conditions in regions of Telangana.