Number of irrigations applied as per irrigation scheduling
Within the treatments, irrigation scheduling at 0.8 IW/CPE ratio requires more water (400 mm) with a total of eight irrigation during summer 2017. Whereas, scheduling of irrigation at 0.6 and 0.4 IW/CPE ratio each required five irrigations of 250 mm. During
kharif 2017, 0.4 and 0.8 IW/ CPE irrigation schedule with 100 and 200 mm of water with two and four irrigations were applied, respectively. In the crop of
rabi’ 2017, scheduling of irrigation at 0.8 IW/CPE ratio required 450 mm, whereas, with 0.6 IW/CPE applied 350 mm and 0.4 IW/CPE used 250 mm during the crop season and the data are presented in Table 1.
Growth attributes
Plant height and dry matter production were influenced by irrigation scheduling and nutrient management practices (Table 2). The significantly taller plants of 52.79, 51.21 and 50.06 cm and dry matter production of 5328, 5076 and 5323 kg ha
-1 at harvest during
kharif, rabi and summer, respectively were observed with irrigation scheduling of 0.8 and 0.6 IW/CPE each with 75 and % RDF + 5 tones/ha of charred rice husk along with seed treatment of
Arbuscular mycorrhiza and which was comparable with each other. The increased soil moisture availability to the crop might have provided optimum moisture supply and uptake by the crop resulting in increased cell division, stem elongation and finally increased plant height and dry matter production. Further, conjugation of
Arbuscular mycorrhiza could have paved to create more adsorptive surface for the uptake of nutrients by the crop. Earlier work of
Ahlawat and Gangaiah (2010) collaborate with the above results. The lower plant height was observed with irrigation scheduling at 0.4 IW/CPE which was due to the decreased soil moisture availability has resulted in stunted growth, probably with decreased absorption of water, leading to poor growth during all the seasons. Similar work has been reported by
Hassan et al., (2016).
Pod and haulm yield
Irrigation scheduling and nutrient management practices also significantly influenced the pod yield, irrigation scheduling at 0.8 IW/CPE ratio with 75% RDF + 5 tones/ha of charred rice husk along with seed treatment of
Arbuscular mycorrhiza recorded the higher pod yield and haulm yield of 2099 and 5062 kg ha
-1, 2063 and 5083 kg ha
-1 and 2003 and 4984 kg ha
-1 respectively (Table 3). This was comparable with irrigation scheduling of 0.6 IW/CPE ratio with 75% RDF + 5 tones/ha of charred rice husk along with seed treatment of
Arbuscular mycorrhiza. This could due to the incorporation of rice husk as basal That increased the water and nutrients availability for longer period and enhanced the yield. The lower pod yield of 1288, 1206 and 1236 kg ha
-1 and haulm yield of 3768, 4016 and 4023 during
kharif, rabi and summer, respectively. The presence of growth-promoting substances due to colonization of
Arbuscular mycorrhiza promoted plant growth and could have increased chlorophyll production by boosting the photosynthetic process and stimulating vegetative growth. Thus, an overall plant performance would have enhanced and finally reflecting through increased production of haulm were observed with irrigation scheduling at 0.4 IW/CPE ratio with 50% RDF + 5 tones/ha of charred rice husk during all the seasons. The results were in similarity to the findings of
Gouda et al., (2018).
Green and blue water
The green and blue water, were calculated from the volume of water used in different irrigation scheduling during summer,
kharif and
rabi seasons are presented in Table 4. Among the different treatments, 0.6 IW/CPE ratio recorded higher green water of 1320 m
-3 ha
-1 during summer. The lowest green water was recorded with 0.8 IW/CPE ratio with a value of 740 m
-3 ha
-1. During
kharif season, at 0.4 IW/CPE ratio was recorded highest green water with the value of 3106 m
-3 ha
-1. Among the irrigation scheduling, 0.8 IW/CPE ratio recorded the lowest green water with a value of 2408 m
-3 ha
-1. Irrigation scheduling of 0.8 IW/CPE ratio was showed more blue water with a value of 4000, 2000 and 4500 m
-3 ha
-1 during summer,
kharif and
rabi season, respectively. Whereas, the lowest blue water was observed with 0.4 IW/CPE ratio in summer,
kharif and
rabi season. Comparing these results with those obtained in this study, it was found some similarity in the green water footprints by
Mekonnen and Hoekstra, (2010).
Water use efficiency
As regards to water use efficiency, the highest water use efficiency was registered with 0.8 IW/CPE ratio and application of 75% of RDF with 5tones/ha charred rice husk along with seed treatment of
Abuscular mycorrhiza with a value of 4.35, 7.37, 5.27. Invariably in all the seasons, irrigation scheduling of 0.4 IW/CPE ratio with an application of 50% of RDF and 5 tones/ha charred rice husk registered the lowest water use efficiency and the data are furnished in Table 5. Hence, it can be very well stated that the application of charred rice husk improved the water retention in the soil as compared to control. Earlier studies by
Karam et al., (2009) had shown that the application of charred rice husk resulted in a reduction of water through evaporation due to improvement in soil physical properties such as increased soil aggregations and improved water holding capacity.
Water productivity
The data on water productivity are furnished in Table 5. Irrigation scheduling of 0.6 IW/CPE ratio with an application of 75% of RDF along with the application of 5 tones/ha charred rice husk registered the higher water productivity of ₹ 285.40 and ₹ 256.71 m
-3 during summer and
kharif season, respectively. Whereas, irrigation scheduling of 0.8 IW/CPE ratio and application of 50% of RDF with 5 tones/ha charred rice husk recorded the lower value of ₹ 202.26 and ₹ 217.29 during summer and
rabi season, respectively. Similar results were observed by
Prajapati et al., (2007).