PG Thesis
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Item Irrigation scheduling and live mulching in upland rice (Oryza sativa L.)(Department of Agronomy, College of Horticulture, Vellayani, 2018) Aparna, R A; Jayakrishnakumar, VThe experiment entitled ‘Irrigation scheduling and live mulching in upland rice (Oryza sativa L.)’ was undertaken at farmer’s field at Peringammala, Kalliyoor, Thiruvananthapuram during Virippu 2017 to standardize irrigation schedule for economizing water use and study the effect of live mulching with cowpea on growth and yield of upland rice. Prathyasa (MO 21) was used as the variety. The experiment was laid out with 14 treatment combinations involving seven irrigation treatments (I1 - irrigation at 3 cm depth at 10 mm CPE, I2 - irrigation at 3 cm depth at 20 mm CPE, I3 - irrigation at 3 cm depth at 30 mm CPE, I4 - irrigation at 2 cm depth at 10 mm CPE, I5 - irrigation at 2 cm depth at 20 mm CPE, I6 - irrigation at 2 cm depth at 30 mm CPE and I7 - rainfed control) and two mulching treatments (M1 - no live mulching, M2 – live mulching with cowpea) with three replications in randomized block design. The results revealed that I1 recorded the highest value for the growth characters viz., plant height at 60 DAS, tiller number m-2 at 60 DAS, LAI at 60 DAS and DMP at harvest. At harvest, the tallest plants were produced by I4. M2 registered the highest dry matter production at harvest. The interaction i1m2 recorded the highest tiller number m- 2 . The yield attributes and yield were significantly influenced by the irrigation treatments. The treatment I1 recorded the highest length of panicle, weight of panicle, number of filled grains panicle-1 and thousand grain weight. M2 produced the highest productive tillers m-2. I1 registered the highest grain yield (2949 kg ha-1), straw yield (3100 kg ha-1) and harvest index (0.49). The grain and straw yields were the highest for M2. The grain yield (3057 kg ha-1) was the highest for i1m2 and significantly superior to other treatments. It was noticed that I1 recorded the highest relative leaf water content and I7 registered the highest proline content. The uptake of N, P and K differed significantly. I1 and M2 recorded the highest NPK uptake. The interaction effect i1m2 registered the highest values for N and P uptake. The root characters viz., root volume, root dry weight and root shoot ratio were significantly increased due to irrigation and I1 recorded the highest values. The root length was the highest for I7. Among the mulches, M2 recorded the highest root length and root shoot ratio. The highest consumptive use was recorded by I1, M2 and their interaction i1m2. The highest water use efficiency (3.72 kg ha-1 mm-1) was recorded by I5 and was on par I3 and superior to other treatments. M2 registered the highest WUE (3.51 kg ha-1 mm-1) and superior to M1. The available N, P and K status were the highest for I7. The available soil N and K were the highest for M2. The interaction effect i7m2 registered the highest values for available soil N and K. The highest weed dry weight was recorded by I1, M1 and their interaction i1m1. The highest net income was obtained with I1 and was on par with I2 and I4. The highest BCR was recorded by I2 and was on par with I4 and I1. M2 recorded the highest net income and BCR. The interaction i1m2 recorded the highest net income and was on par with i4m2. The interaction i1m2 registered the highest BCR (1.46) and was on par with i2m1, i2m2, i4m2 and i5m2. The results revealed that frequent irrigation especially at 3 cm depth at 10 mm CPE in combination with live mulching of cowpea favourably influenced most of the growth, yield attributes, yield, physical, chemical properties of the soil and economics of cultivation. Although the highest grain yield was recorded by i1m2, it was found that i1m2 was on par with i4m2 for net income suggesting that irrigation at 2 cm depth at 10 mm CPE with live mulching of cowpea is as good as i1m2. For BCR, i1m2 was on par with i2m1 , i2m2 , i4m2 and i5m2 suggesting that irrigation at 2 cm depth at 20 mm CPE with live mulching of cowpea is as good as i1m2. For higher water use, irrigation at 2 cm depth at 20 mm CPE (I5) and live mulching of cowpea (M2) can be recommended. From farmer’s point of view, irrigation at 2 cm depth at 10 mm CPE with live mulching of cowpea is beneficial for higher economic returns in acute water deficit areas.Item Water and weed management for aerobic rice(Department of Agronomy, College of Horticulture, Vellanikkara, 2017) Akhil T Thomas; Deepa ThomasAerobic rice culture is a technology to improve the water productivity in rice culture. Water and weed management are two important aspects of this promising technology. It is well established that yield reduction in rice happen if the soil moisture level falls below the field capacity. Unlike in flooded conditions,weeds pose greater problem in aerobic rice production.A field study was undertaken at Agronomic Research Station (ARS), Chalakudy from September 2016 to January 2017 for developing appropriate water and weed management strategies for aerobic rice. The treatments comprised of three levels of irrigation in the main plot (irrigation at 10 mm cumulative pan evaporation (CPE), 20 mm CPE and 30 mm CPE) and five weed management treatments in the subplot (pre emergent herbicide oxadiargyl followed by hand weeding, oxadiargyl followed by 2,4- D sodium salt, oxadiargyl followed by bispyribac sodium at 20 days after sowing (DAS), hand weeding at 20 and 40 DAS and an unweeded control). Depth of irrigation was 3 cmand the total water applied including effective rainfall amounted to 933 mm, 574 mm, 403 mm in I1, I2 and I3 respectively. Irrigation at 10 mm CPE recorded higher values for growth parameters like plant height and number of tillers per meter as well as yield and yield attributes.Higher root volume also was recorded in these plots .Relative leaf water content and chlorophyll content were higher under frequently irrigated plots (10 mm CPE) than less irrigated plots. Moisture stress lead to inhibition of leaf production and decline in leaf area in aerobic rice. Higher availability of moisture, reduced stress, better growth and yield attributes contributed to higher yield under irrigation at 10 mm CPE. Moisture stress caused reduction of 44 percent grain yield under irrigation at 30 mm CPE over irrigation at 10 mm CPE. Hand weeding at 20 and 40 DAS resulted in better growth, yield and yield attributing factors of aerobic rice. Oxadiargyl followed by bispyribac sodium at 20 DAS and oxadiargyl followed by hand weeding at 20 DAS were the next bettertreatments which were on par.Weed competition resulted in 64 percent reduction in grain yield. Oxadiargyl when applied pre-emergent waseffective in controlling the first flush of weeds in the field. All the treatment combinations with oxadiargyl recorded the lower weed dry matter production and weed density. As the crop advanced to flowering, hand weeding at 20 and 40 DAS resulted in lower weed dry matter production and weed density. Better growth and yield in this treatment suggested a long critical period of weed competition in aerobic rice. Irrigation at 30 mm CPE registered the highest water productivity of 0.96 kg m-3, but with severe yield loss. Among weed management treatments hand weeding at 20 and 40 DAS recorded the highest water productivity (1.13 kg m-3) and the lowest was from unweeded control (0.37 kg m-3). Irrigation at 10 mm CPE in combination with hand weeding at 20 and 40 DAS registered the highest growth and grain yield (2791 kg ha-1) and recorded water productivity of 0.88 kg m-3. However irrigation at 10 mm CPE in combination with oxadiargyl followed by bispyribac sodium at 20 DAS resulted in the highest net return (Rs 51477 per hectare) and B:C ratio (2.3).