Effect of Water Management, Systems of Cultivation on Grain Yield and Energy Budget of Rice Varieties

Aims of Study: This research focused on assessing the grain yield and energy performance of four rice cultivars under different irrigation regimes and systems of cultivation for suitability of Andhra Pradesh and Telangana. Experiment Design: The split-split plot design with three replications was performed for this study. The treatment comprised of two irrigation regimes viz., Alternate Wetting and Drying (AWD) and saturation as the main plot treatments, three systems of cultivation viz., System of Rice Intensification (SRI), Drum Seeding (DS) and Normal Transplanting (NTP) as the subplot treatments, and four cultivars namely DRR Dhan 42, DRR Dhan 43, MTU-1010, and NLR-34449 as the sub-sub plot treatments. Place and Duration of Study: An experiment was conducted at the Indian Institute of Rice Research, Hyderabad, during the Autumn 2017 and 2018. Result: Among the irrigation regimes, AWD recorded higher grain yield than saturation, Gross output energy, and net energy as compared to saturation. SRI significantly recorded higher grain Original Research Article Nayaka et al.; IJPSS, 33(17): 70-81, 2021; Article no.IJPSS.71534 71 yield over the NTP method. Among the different rice cultivars, DRR Dhan 43 registers remarkably higher grain yield than other cultivars during 2017 and 2018. The cultivar DRR Dhan 43 recorded higher gross output energy, net energy compared to other rice cultivars.


INTRODUCTION
Rice is grown in an area of 44.5 M ha with a production of 115.60 M t and productivity of 2800 kg ha -1 in India [1]. Primary field preparation and nursery require bountiful measures of water and transplanting of rice manually is laborious, time taking and causes drudgery. Lack of timely availability of labor for transplanting many times ends up in late planting leading to poor yields [2]. Besides, the conventional submerged irrigation is laborious and time-consuming water expends a huge amount of labor, time, and energy for the increased pumping water in flooded fields [3]. To produce 1 kg of the un milled rice grain, the virtual water use was up to 5,000 liters [4]. Among the various techniques, the most extensively promoted one for the cultivation of rice is AWD irrigation [5]. Therefore, rice might face a threat due to water shortage and hence it's needed to follow water-saving strategies in rice cultivation so that production and productivity levels are elevated despite the looming water crisis. Among the strategies for rice cultivation, the system of rice intensification method envisages on alternate wetting and drying could facilitate to chop back water losses and improve productivity.
The growing worldwide demand for energy by the agricultural sector to meet the food demand of more than 7 billion people results in detrimental effects on the environment and the health of the farmers. If the energy in the agricultural sector is used judiciously, it will not only reduce the environmental impacts in terms of greenhouse gases (GHG) emissions and other hazardous effects but will also lead to a desirable sustainable form of agriculture [6]. A higher input of energy accounts for higher energy costs, which significantly reduces the net return of the farms and is a challenging issue for the policymakers. In many advanced agricultural systems, an increase in yield is the result of an augmented energy input that is directly related to the use of improved mechanized tools and the introduction of high-yield crop varieties. In most developing nations, agriculture is the mainstay of the economy and a source of employment for a large proportion of the population. Mechanization reduces human drudgery, ensures timeliness of farm-related activities, and increases farm output in terms of productivity [7]. In Indian agriculture, there is agro ecological diversity in soil, rainfall, temperature, and cropping systems. To meet the need for operational energy and reduce the share of animal power, the contribution of mechanical energy increased substantially, which directly resulted in increased use of fossil fuels, mainly diesel [8]. The key drivers of energy use in the agricultural sector in India are agricultural production, the extent of arable land used for crop production, and the penetration of efficient technologies, such as irrigation facilities and improved mechanization means [9]. Currently, cropping systems are increasing their energy inputs; therefore, there is a need to ascertain the efficiency of the system in terms of energy use. In this context, it is imperative to thoroughly budget the energy use of the widely followed cropping systems to identify the processes and systems that are the most energy-consuming and can be replaced with other low input-energy-consuming practices, to conserve energy and achieve sustainable cropping systems [10].
There has always been a lot of debate on the economic and environmental performance of smaller farms as compared to larger farms. The study also intends to report the performance of marginal, small, and medium farms, in terms of energy indicators and eco-efficiency. Therefore, to assess key energy indicators, such as Energy input, gross energy output, Net Energy, and Energy use efficiency (EUE). Among the varied production factors, a varietal choice at any location plays an important role. Several rice cultivars vary in their performance under different systems of cultivation. One option is to identify rice genotypes that will adapt to specific locations and soil textures. Hence, this study was conducted using 4 rice cultivars which grown under different systems of cultivation. Recently some of the high yielding rice cultivars viz., DRR Dhan 42, DRR Dhan 43, MTU-1010 and NLR-34449, etc., were released for Telangana and Andhra Pradesh. Precise crop management depends on the growth characteristics of different varieties to get maximum yields. available nitrogen, phosphorus, and potassium respectively. The treatments consisted of two irrigation regimes alternate wetting and drying (AWD) and saturation as main plot treatments, three systems of cultivation viz., a system of rice intensification (SRI) with a spacing of 25 cm x 25 cm, drum seeding (DS) with the spacing of 20 cm x 10 cm and normal transplanting (NTP) with the spacing of 20 cm x 15 cm as subplot treatments and four cultivars namely DRR Dhan 42, DRR Dhan 43, MTU-1010 and NLR-34449 as sub-sub plot treatments laid out in split-split plot design with three replications. The area of each gross plot was 7 x 3 m 2 . Seedlings were transplanted with an average of one seedling per hill in the SRI method of planting. FYM at @ 10 t ha -1 was uniformly applied to all the plots before final puddling and leveling. The recommended dose of phosphorus @ 60 kg P 2 O 5 kg ha -1 as single super phosphate (SSP) was applied to all the treatments uniformly as basal and potassium @ 40 kg K 2 O ha -1 as muriate of potash (MOP) was applied in two splits, 75 percent as basal and the remaining 25 percent at 75 DAS/DAT. The recommended dose of nitrogen (120 kg ha -1 ) was applied through urea in three splits, 50 percent as basal, 25 percent at 50 DAS/DAT, and the remaining 25 percent at 75 DAS/DAT.

Total Number of Tillers
Five plants were selected and randomly tagged in each net plot, the total tillers were counted hill -1 and expressed like the total number of tillers m -2 in four stages viz., 30, 60, 90 DAS/DAT, and at harvest.

Grain Yield and Straw Yield
Plants within the net plot area were harvested separately in each plot, threshed and the grains were separated, dried under the sun and the grain yield per plot was recorded after cleaning. From this, the yield per hectare was computed and expressed in kg ha -1 . After threshing the grain, the leftover straw was dried under the sun and the yield per plot was recorded and the yield per hectare was computed and expressed in kg ha -1 .

Total Input Energy
Direct energy inputs include the total quantity of fossil fuel used in land preparation, harvesting, human labor, and electricity, while indirect energy inputs are, energy used in the production of machinery and raw materials like mineral fertilizers, pesticides, and seed inputs and transportation [11]. A complete inventory of all the crop inputs (fertilizers, seeds, plant protection chemicals, fuel, human labor, irrigation water, and machinery power) and outputs of both grain and straw yields were recorded. The energy input in different treatments was computed by multiplying the input with the corresponding energy coefficients and summing up all these coefficients. The indirect energy use of agricultural machinery was calculated by using the following equation.

Total output energy
The output energy from the main product (grain) and byproduct (straw) was calculated by multiplying the amount of production and the corresponding energy equivalent and expressed as GJ ha -1 .

Net Energy (GJ ha -1 )
The net energy was calculated by using the following formula Net energy = Gross energy output (GJ ha -1 ) -Energy input (GJ ha -1 )

Total Energy Use Efficiency
The total energy use efficiency was calculated using the following formula.

Statistical Analyses
The information obtained on the various growth and yield parameters and yield were statistically analyzed by the method of analysis of variance as per the procedure outlined for the split-split plot design given by Gomez and Gomez [12]. The statistical implication was tested by F value at 0.05 level of probability and the critical difference was figured out where ever the consequences were significant.

Number of Tillers m -2
The average number of tillers m -2 of rice linearly increased up to 60 DAS/DAT, and thereafter it was slightly declined, which could be due to selfthinning mechanism, resource constraint, or intra plant competition [13 and 14]. More number of tillers m -2 was recorded in 2018 due to timely sowing and transplanting as compared to 2017. The number of tillers m -2 of rice as influenced by the different irrigation regimes, systems of cultivation and cultivars were statistically analyzed and presented in Table ( [18]. Among the different systems of cultivation, the system of rice intensification recorded a significantly superior number of tillers m -2 at 30, 60, 90 DAS/DAT and at harvest (138, 357, 332, and 320 tillers m -2 respectively in pooled means of both the years) as compared to normal transplanting (NTP) (121, 294, 269 and 257 tillers m -2 respectively in pooled means of both the years) and drum seeding (125, 342, 317 and 305 tillers m -2 , respectively in pooled means of both the years). The number of tillers m -2 of rice cultivars was found to be significantly varied at all the growth stages of rice. Transplanting of younger seedlings might have improved the tillering capacity of the crop in the SRI [19]. This could be attributed to better aeration and less competition between plants because of wider spacing for nutrients and light. These results corroborate with the findings of Hugar et al. [20], Mohanty et al. [21], Sudhakara [22], and Thirupathi [23]. At 30 DAS/DAT a significantly higher number of tillers, m  (Table 1). The variation in the number of tillers m -2 among the varieties was due to the genetically inherent character of the cultivars. These results corroborate with the findings of Sharath [24] and Vijay [25].

Grain Yield
Despite the treatment differences, higher grain yield was recorded during the second year than the first year and it may be attributed to congenial weather conditions such as solar radiation and temperature, timely sowing, and yield attributes during Autumn 2018. The grain yield was significantly influenced by different irrigation regimes, systems of cultivation, and cultivars during 2017 and 2018 (Table 2).
Among the irrigation regimes, AWD irrigation practice throughout the crop growth period recorded higher grain yield (5755, 5952 and 5854 kg ha -1 in 2017, 2018 and pooled means, respectively) than saturation (5346, 5491 and 5439 kg ha -1 in 2017, 2018, and in pooled means, respectively). This could be because of favorable vegetative growth and development as they received intermittent and sufficient moisture at the proper amount and critical stages during the entire period of growth. Thus, maintained favorable soil water balance under alternate wetting and drying helped the crop plants to improve performance over-saturation because water plays a vital role in the carbohydrate metabolism, protein synthesis, cell division, cell enlargement, and partitioning of photosynthates to sink for enhanced development of growth characters. Frequent irrigations created favorable moisture regimes which enabled the crop to grow lavishly by providing conducive micro-climate and increasing solubility, absorption, translocation, and assimilation of nutrients by the plants for various physiological processes. The favorable growth traits enhanced the yield attributing characters with a higher source to sink exchange that resulted in higher grain yield. The above result is by the earlier reports of Thiyagarajan et al. [26] and Geethalakshmi et al. [27]. On the other way, hairline crack formation in AWD techniques of irrigation resulted in a higher level of yield. These results were earlier confirmed by Kumar et al. [28], and Majid [29].
Among the different systems of cultivation, the SRI recorded significantly higher grain yield (5953, 6129, and 6041 kg ha -1 during 2017, 2018, and in pooled means, respectively) over the normal transplanting method (5144, 5259 and 5202 kg ha -1 during 2017, 2018 and in pooled means, respectively). This was however on par with the drum seeding method (5784, 5826, and 5805 kg ha -1 during 2017, 2018, and in pooled means, respectively). The SRI method provides wider spacing, better aeration, and limited competition, which enabled the plants to grow lavishly. The enhanced seed yield in the SRI can be attributed to the more root growth that enabled them to access nutrients from a larger volume of soil. Similar results were revealed earlier by Thiyagarajan et al. [26] and Rajendran et al. [30]. Adequate vegetative growth with efficient dry matter accumulation and effective partitioning to panicles resulted in a higher number of panicles m -2 and grains panicle -1 , in the SRI method, wherein crop was transplanted at a younger seedling stage which was reflected in its grain yield. These findings are in agreement with the earlier reports of Manjunatha et al. [31] and Venkateswarlu et al. [19]. The yield attributing characters viz., number of grains panicles -1 , number of filled grains panicles -1 were higher in an SRI method than in drum seeding and normal transplanting, which are responsible for the increased grain yield [32, 33, 34 and 21].Among the different rice cultivars, DRR Dhan 43 registered notably higher grain yield than other cultivars during 2017 and 2018.Higher grain yield was noticed in DRR Dhan 43 (6055, 6122 and 6089 kg ha  Table 2). The rice cultivars which produce a greater number of tillers m -2 (Table 1) produce the higher seed yield.

Straw Yield
The straw yield was influenced by different irrigation regimes, systems of cultivation, and cultivars during in 2017 and 2018 (Table 2). Within irrigation regimes, alternate wetting and drying methods significantly recorded higher straw yield (6287, 6558, and 6423 kg ha -1 during 2017, 2018, and in pooled means, respectively) than saturation (5878, 6011 and 5995 kg ha -1 in 2017, 2018, and pooled means, respectively). This is because of adequate moisture availability that contributed to enhanced dry matter production and accumulation. A similar outcome was revealed by Sariam and Anuar [35], Rahaman and Sinha [36], and Kumar et al. [18]. Among the different systems of cultivation, the SRI method recorded higher straw yield (6246-6546, and 6396 kg ha -1 during 2017, 2018, and in pooled means, respectively) over other systems of cultivation. This might be due to a higher number of tillers hill -1 because of transplanting younger seedlings in case of a system of rice intensification. NTP method recorded the lowest straw yield than other systems of cultivation which was due to uneven plant stand and and less number of tillers per unit area. The above result is following the results of Manjappa and Kataraki [37], and Jayadeeva and Shetty [38]. Among the different rice cultivars, DRR Dhan 43 recorded significantly higher straw yield than other cultivars (6459, 6981, and 6620 kg ha

Input Energy
Between the irrigation regimes, saturation recorded significantly higher input energy (18.4, 17.5, and 18.0 GJ ha -1 during 2017, 2018, and in pooled means, respectively) over alternate wetting and drying. This was mostly due to a higher number and amount of irrigations given in saturation than the AWD method. The input energy required was significantly higher in normal transplanting (18.8, 17.9, and 18.4 GJ ha -1 during 2017, 2018, and in pooled means, respectively) as over drum seeding and SRI methods. In drum seeding labor energy used was minimal, but in the case of normal transplanting, the usage of more labor resulted in increased total input energy used than other systems of cultivation. Significant variations in grain and straw yields brought out dissimilarity in gross output energy among the different irrigation regimes, systems of cultivation, and cultivars during 2017 and 2018 (Table 3). Among the rice cultivars, significant differences were found regarding input energy during 2017 and 2018. DRR Dhan 42 noticed appreciably higher input energy (18.7, 18.2, and 18.5 GJ ha -1 during 2017, 2018, and in pooled means, respectively) over other cultivars. However lower input energy was observed in DRR Dhan 43 (Table 3).

Gross Output Energy
AWD method of irrigation registered significantly higher gross output energy (184.8, 178.4, and 181.6 GJ ha -1 during 2017, 2018, and in pooled means, respectively) than saturation. Higher gross output energy was attributed to higher grain and straw yields under alternate wetting and drying. This result conforms to the findings of Alam et al. [39] and Thirupathi [23]. SRI recorded appreciably higher gross output energy (185.0, 178.1, and 181.6 GJ ha -1 during 2017, 2018, and in pooled means, respectively) over normal transplanting and drum seeding. The higher grain and straw yields in the SRI method led to higher gross output energy. This result conforms to the reports of Jayadeva et al. (2010). Among the different cultivars, DRR Dhan 43 resulted in significantly superior gross output energy (183.2, 180.6, and 181.9 during 2017, 2018, and pooled means, respectively) compared to other rice cultivars (Table 3). It is because of higher grain and straw yields in DRR Dhan 43 which led to higher gross output energy.

Net Energy
In irrigation regimes, alternate wetting and drying significantly recorded higher net energy (167.0, 161.8, and 164.4 GJ ha -1 during 2017, 2018, and in pooled means, respectively) than saturation. This was due to higher grain and straw yields which led to higher net energy in AWD. Among the systems of cultivation, SRI significantly recorded higher net energy (169.6, 163.6, and 166.6 GJ ha -1 during 2017, 2018, and in pooled means, respectively) than normal transplanting and drum seeding. This was mainly due to higher grain yield and straw yield which resulted in higher net energy in the SRI over other systems of cultivation. This result conforms to the reports of Jayadeva et al. [40] and Babu et al. [41] Sudhakara [22] and Thirupathi(2017 during 2017, 2018, and pooled means, respectively) than other rice cultivars (Table 3). Due to higher grain and straw yields in DRR Dhan 43 led to higher net energy.

Energy Use Efficiency
In irrigation regimes, saturation recorded higher energy use efficiency (1.12, 1.12, and 1.12 % during 2017, 2018, and in pooled means, respectively) than AWD. This might be due to lower net energy response for output energy. The energy use efficiency recorded was significantly higher in the NTP (1.12, 1.12, and 1.12 % in 2017, 2018, and in pooled means, respectively) than other (Table 3). This was mainly due to lower grain and straw yields coupled with lower net energy. Higher energy use efficiency under the system of rice intensification method was reported by many research workers (42,40,41]. Among the different rice cultivars, DRR Dhan 43 recorded appreciably higher energy use efficiency (1.12, 1.12, and 1.12 % during 2017, 2018, and pooled means, respectively) over other cultivars.

CONCLUSIONS
 The irrigation regime of AWD performed well with respect to grain yield, and straw yield as compared to saturation. Saturation significantly recorded higher input energy. Gross output energy, net energy was higher with AWD as compared to the saturation  The SRI was better in terms of grain and straw yields over the normal transplanting method. The normal transplanting method required higher input energy. The gross energy output, net energy was significantly superior in SRI than other systems of cultivation.