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Aerobic rice is one of the alternative methods for saving water, energy, labour, time and reduced methane gas in rice production ecosystem. The field experimental trial was conducted during summer 2018 at Agricultural College and Research Institute, Madurai. Irrigation scheduling based on different IW/CPE (Irrigation Water/Cumulative Pan Evaporation) ratios and different doses along with various spilt applications of nitrogen were experimented. Results of field experiment indicated that irrigation scheduling at IW/CPE of 0.8 up to panicle initiation stage and thereafter IW/CPE of 1.0 up to dough stage recorded the highest root length of 13.0 cm at active tillering and 18.8 cm at flowering stage. But, irrigating the aerobic rice at IW/CPE of 1.0 up to panicle initiation stage and thereafter IW/CPE of 1.2 up to dough stage recorded the highest root volume (16.9, 27.1 cc•hill −1) and root dry weight (6.1, 12.9 g•hill −1) at active tillering and flowering stage. Application of nitrogen at 150 kg•ha −1 in 5 equal splits at 20, 35, 50, 65 and 80 DAS (Days after sowing) recorded the highest root length of 13.5 cm, root volume of 17.6 cc•hill −1 and root dry weight of 6.4 g•hill −1 at active tillering stage and root length of 19.4 cm, root volume of 27.6 cc•hill −1 and root dry weight of 14.4 g•hill −1 at flowering stage. The interaction effect of irrigation and nitrogen significantly influenced the root growth. Irrigation at IW/CPE of 0.8 up to panicle initiation stage and thereafter IW/CPE of 1.0 up to dough stage along with 150 kg N ha −1 in 5 equal splits at 20, 35, 50, 65 and 80 DAS significantly enhanced the root length (15.

More rice needs to be produced with lesser water to feed the increasing human population. Judicious water management practices and appropriate water saving technologies in rice cultivation are in need in the coming decades. Aerobic rice is one of water saving method of rice cultivation. The field experiment was conducted during Summer season of February 2018 to May 2018 at Tamil Nadu Agricultural University, Agricultural College and Research Institute, Madurai, to find out the effect of irrigation schedules with varied doses and time of nitrogen application on yield of aerobic rice. Irrigation scheduling of IW/CPE (Irrigation Water/Cumulative Pan Evaporation) 1.0 up to panicle initiation stage and thereafter IW/CPE 1.2 up to dough stage recorded higher yield attributes viz., number of panicles hill −1 (9.1), number of filled grains panicle −1 (87.9), test weight (15.3 g), grain yield (4462 kg•ha −1), straw yield (5977 kg•ha −1). However, the highest water use efficiency (6.8 kg•ha −1 •mm −1) was recorded in the treatment of IW/CPE 1.0 throughout the crop growth period. Lower yield attributes, yield and water use efficiency were recorded with irrigation scheduling of IW/CPE 0.8 throughout the growth stage. Application of nitrogen at 150 kg•ha −1 in 5 equal splits at 20, 35, 50, 65 and 80 DAS (Days after sowing) recorded higher yield attributes viz., number of panicles hill −1 (9.3), number of filled grains panicle −1 (90.5), test weight (15.4 g), grain yield (4746 kg•ha −1), straw yield (6258 kg•ha −1) and WUE (7.5 kg•ha −1 •mm −1). Application of nitrogen 100 kg•ha −1 in 4 equal splits at 20, 40, 60 and 80 DAS recorded lower yield attributes, yield and water use efficiency. The interaction effect between irrigation scheduling and nitrogen How to cite this paper:

The scheduling of irrigation according to the ratio between irrigation water depth (IW) and cumulative pan evaporation (CPE) rate for aerobic rice. During these days, the shortage of water resources is increasing continually due to climate change. It has led to the adaptation of rice farming under aerobic conditions. This saves irrigation water, labour, eliminates puddling, reduces seepage, percolation losses, and methane emissions. Aerobic rice cultivars produce higher plant growth, physiological, root growth, yield, water use efficiency, productivity, and soil nutrient uptake under different (0.6, 0.8, 1.0, 1.2, 1.4, 1.5, 2, and 2.5) IW/ CPE ratios. Under these irrigation schedules, the yield of rice in aerobic soil is recorded at between 4.5 and 7.1 t ha-1 and the water use efficiency is from 25 to 70 kg ha-1. However, the decline in yield or even crop failure under continuous monocropping, weeds, nematode problems, and aerobic rice micronutrient deficiency Our important findings in aerobic rice are: (1) Scheduling of irrigation based on various IW/ CPE ratios recorded the higher rice plant height, number of tillers hill-1, dry matter production, leaf area index, crop growth rate, relative growth rate, root length, productive tillers, number of grains panicle-1, number of filled grain panicle-1, total number of grains panicle-1, test weight and yield; (2) The last 15 years of aerobic rice research findings focused on irrigation scheduling by IW/CPE ratio for driving economic water use; and (3) nutrient uptake increased with irrigation at more than 1.0 IW/CPE ratio with depth of 5 cm irrigation water. Declining water availability due to climate change makes it necessary to conduct more research on irrigation scheduling in rice crops in order to increase yield and water use efficiency.

The effect of four seedling densities developed soon after the emergence and two shading materials were studied in order to elucidate the response of seedling growth of tobacco. Germination and seedling emergence was better in beds under greycloth than under polythene. In contrast, shoot and root growth of tobacco seedlings was superior under polythene at all densities. This observation is attributed to optimal environmental conditions under polythene. The study also revealed that the highest shoot and root growth was at the lowest density. High plant densities hindered plant growth. Well developed plants were seen at the plant density of 165 plants per 0.1 m2 under polythene.