Irrigation scheduling and live mulching in upland rice (Oryza sativa L.)

Abstract

The 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.