The growth performance of clonal Eucalyptus tereticornis (clone P-21) planted at a spacing of 8 × 2 m was evaluated over two consecutive years. At the time of transplantation (October 29-30, 2016), the clone exhibited uniform growth with an average plant height of 48.9 cm and basal diameter of 3.81 mm, indicating healthy and vigorous planting stock. After three years of plantation, the trees attained an average height of 16.5 m and diameter at breast height (dbh) of 15.5 cm. Further growth assessment during the fourth year showed that the average tree height increased to 17.8 m, while dbh reached 17.1 cm. This reflects an increment of 1.3 m in height and 1.6 cm in dbh over one year, indicating rapid growth and good adaptability of eucalypts under semi-arid conditions. The steady increase in both height and diameter suggests that the species maintained a high growth rate even after canopy development, which has implications for resource competition with intercrops. The observed rapid growth of Eucalypts is consistent with its well-known fast-growing nature and high biomass accumulation potential under agroforestry systems. The significant increase in height and diameter from the third to fourth year reflects the fast- growing nature and high productivity potential of Eucalyptus tereticornis. These findings are in close agreement with the results of Sirohi et al. (2021), who reported that eucalypts clones attained heights up to 14.2 m within three years under agri-silviculture systems in Haryana. The relatively higher growth observed in the present study may be attributed to better clonal performance, site-specific management practices, and favorable environmental conditions Similar findings were reported by Tripathi et al. (2020) who observed that 3.4-4.4 year-old eucalypts trees attained heights of 12.8-13.9 m and dbh of 12.41-13.88 cm under semi-arid conditions, with substantial annual increments in both parameters. Compared to these findings, the present study recorded relatively higher growth, which may be attributed to favorable management practices, site conditions, and clone performance.

The continuous increase in height and dbh from the third to fourth year indicates that eucalyptus trees remain in an active growth phase during early rotation, contributing significantly to biomass production. This is in agreement with the findings of Nirmal et al. (2021) who reported that clonal eucalypts exhibits high productivity and can produce significantly greater biomass compared to seedling-origin plantations due to superior genetic potential and coppicing ability. Tree age and canopy development play a crucial role in determining the extent of tree- crop interaction. For instance, research on eucalyptus- based agroforestry systems demonstrated that crop yield reductions become more pronounced as tree age increases due to increased shading and competition (Ramesh et al., 2023). Availability of light intensity during Kharif and Rabi season under eucalypts based agroforestry system The availability of light intensity under Eucalypts plantation (8×2 m spacing) was assessed at different times of the day from July 2020 to April 2021 and compared with open (sole crop) conditions (Table 1). The data revealed a substantial reduction in incident solar radiation under the eucalypts canopy across both Kharif and Rabi seasons. During Kharif season (July- October 2020), the mean reduction in light intensity ranged from 56.3% (August) to 61.9% (July), with the maximum reduction (61.9%) observed in July. Across different times of the day, the reduction was consistently high, exceeding 60% during most hours, particularly in the afternoon (1 PM to 5 PM), indicating strong canopy interference with solar radiation. In the Rabi season (November 2020-April 2021), the mean reduction in light intensity varied between 54.9% (February) and 59.9% (April). Although slightly lower than Kharif, the reduction remained substantial throughout the season. The lowest reduction was observed during February (54.9%), possibly due to partial leaf shedding and lower canopy density, whereas higher reductions in March and April may be attributed to renewed canopy development. Overall, the results clearly indicate that light availability under eucalypts plantation was reduced by approximately 55-62% throughout the year, and the light intensity received under sole cropping conditions remained significantly higher during all months and time intervals.

The marked reduction in light intensity under eucalypts based agroforestry systems observed in the present study is primarily due to canopy development, leaf area expansion, and tree architecture, which intercept and absorb a large proportion of incoming solar radiation. These findings are in close agreement with Sirohi et al. (2021), who reported significant shading effects of eucalypts plantations on understory crops in semi-arid regions of Haryana, leading to reduced light availability and crop productivity. The higher reduction in light intensity during Kharif season, particularly in July (61.9%), may be attributed to peak vegetative growth and maximum canopy cover during the monsoon period. Similar observations were reported by Chavan et al. (2024), who noted that canopy expansion in eucalypts based systems leads to maximum radiation interception during the rainy season, thereby limiting light penetration to the understory crops. The relatively lower light reduction during February (54.9%) suggests a seasonal variation in canopy density, possibly due to partial leaf fall or reduced leaf area index during winter. This seasonal fluctuation in light transmission has also been reported by Ramesh et al. (2023), who observed that light interception in agroforestry systems varies with phenological stages of trees and significantly affects crop growth and yield.

Furthermore, the diurnal variation indicates that light reduction was consistently high throughout the day, with slightly greater reductions during midday and afternoon hours (1 PM-5 PM). This is critical because these hours correspond to peak photosynthetically active radiation (PAR), and reduced light during this period can severely affect photosynthesis and biomass accumulation of intercrops. Similar findings were

Table 1: Per cent reduction in available sun light in eucalypts based agroforestry system over control during Kharif and Rabi seasons

reported by Kumar et al. (2021), who emphasized that reduced PAR under eucalypts canopy significantly limits crop growth due to shading effects. The overall reduction of more than 50% light intensity observed in the present study clearly indicates that light becomes a major limiting factor in eucalypts based agroforestry systems. This reduced light availability directly affects photosynthesis, dry matter accumulation, and ultimately crop yield.

Grain and Stover yield (t/ha) of moong

The data presented in Table 2 revealed that the yield of moong crop was significantly influenced by eucalypts based agroforestry system as compared to sole cropping. The grain yield of moong under eucalypts plantation (8×2 m spacing) was recorded as 0.68 and

0.58 t ha-1 during 2019-20 and 2020-21, respectively, whereas the corresponding grain yield under sole cropping (control) was higher, i.e., 0.88 and 0.84 t ha-1. This indicates a reduction of about 22.7% and 30.9% in grain yield under agroforestry system during the respective years. Similarly, stover yield was also reduced under eucalypts based agroforestry system (1.48 and 1.28 t ha-1) as compared to sole cropping (1.81 and 1.78 t ha-1). The reduction in yield under eucalypts based agroforestry system can be attributed to competition for essential growth resources such as light, moisture, and nutrients. The shading effect of tree canopy reduces the availability of photosynthetically active radiation (PAR), thereby limiting photosynthesis and biomass accumulation in understory crops. Similar findings were reported by Kumar et al. (2022) where significant reduction in yield of intercrops including pulses under eucalypts plantations was observed due to reduced light interception. Likewise, Newaj et al. (2020) reported that grain yield of blackgram decreased under eucalypts based agri- silviculture system compared to sole cropping, with higher reduction at closer spacing due to increased competition.

The comparatively higher reduction observed during 2020-21 might be due to increased canopy development of eucalypts trees with age, leading to greater shading and resource competition. Earlier studies have also shown that yield reduction tends to increase with tree age and canopy expansion (Dhiman and Gandhi, 2020). Overall, the results clearly indicate that although eucalypts based agroforestry systems provide additional benefits such as timber and ecological services, they significantly reduce the productivity of moong crop.

The data presented in Table 3 indicated that green fodder yield of cowpea was markedly influenced by eucalypts based agroforestry system. The green fodder yield under eucalypts plantation (8×2 m spacing) was recorded as 15.64 t ha-1 in 2019-20 and 12.84 t ha-1 in 2020-21, whereas significantly higher yields of 21.62 and 20.15 t ha-1 were obtained under sole cropping (control). This reflects a reduction of about 27.7% and 36.3% in green fodder yield under eucalypts during the respective years. The reduction in green fodder yield under eucalypts based system can be primarily attributed to interspecific competition for light, soil moisture, and nutrients. The shading effect of eucalyptus canopy reduces light availability, which directly affects photosynthesis and vegetative biomass production, particularly in fodder crops like cowpea that depend on rapid vegetative growth. These findings are strongly supported by the work of Sirohi et al. (2022a) on fodder crops under poplar based agroforestry systems with different spacings. Their study revealed that fodder yield increased with increase in tree spacing and was maximum under wider spacing (8×3 m), while significantly lower yields were recorded under closer spacings (3×3 m). They further reported that fodder crops such as cowpea, sorghum and berseem produced significantly higher biomass in open conditions (control) compared to poplar based systems due to reduced competition.

Table 2: Yield (t/ha) of moong under eucalypts based agroforestry system

Table 3: Green fodder yield (t/ha) of cowpea under eucalypts based agroforestry system

Similar findings were reported by Kumar and Nandal (2004) who observed that all intercrops grown under eucalypts exhibited reduced plant vigour and yield compared to open conditions, with reductions depending on crop type and intensity of competition. The greater reduction in fodder yield during 2020-21 compared to 2019-20 may be attributed to increased canopy development and root expansion of eucalypts trees over time, leading to higher competition for light and below-ground resources. This trend is consistent with findings of Newaj et al. (2020), who reported increased yield reduction of intercrops with advancing age of eucalypts plantations as competition intensifies with tree growth. Overall, the results clearly demonstrate that although eucalypts based agroforestry systems provide long-term economic and ecological benefits, they significantly reduce the green fodder yield of cowpea.

The data revealed that wheat yield was significantly influenced by eucalypts based agroforestry system (Table 4, 5, 6). The grain yield under eucalypts (8×2 m spacing) was recorded as 3.80 and 3.27 t ha-1 during 2019-20 and 2020-21, respectively, which was considerably lower than the sole crop yield (4.59 and

4.62 t ha-1). Similarly, straw yield was also reduced under eucalypts (4.05 and 3.58 t ha-1) compared to control (5.59 and 5.60 t ha-1). The reduction in grain yield ranged from about 17-29%, while straw yield decreased by about 27-36%. This reduction is mainly attributed to competition for light, moisture, and nutrients between trees and crops. Shading by eucalypts canopy reduces photosynthetically active radiation, thereby lowering biomass production. Similar findings were reported by Sirohi et al. (2021) where grain and straw yield of barley under eucalypts decreased by 14-30% due to resource competition. Likewise, Kumar and Nandal (2004) reported that wheat yield under eucalypts decreased up to 62.3% compared to sole cropping due to reduced plant vigour and resource competition. Similarly, Panozzo et al. (2026) reviewed global agroforestry systems and reported that cereal crops like wheat generally experience yield reductions under tree-based systems unless appropriate management practices such as pruning, wider spacing, and selection of compatible crop varieties are adopted. Scordia et al. (2023) reported that wheat productivity showed positive responses to tree cover only under particular conditions-specifically in certain years or at sites experiencing high temperatures and elevated potential evapotranspiration (PET). Ong et al. (2015) working on tree-crop interactions in tropical agroforestry systems, concluded that competition for light is the primary factor limiting cereal crop productivity under tree canopies. They emphasized that reduction in photosynthetically active radiation significantly affects wheat growth and yield components. The results are in close conformity with the findings of Sirohi et al. (2022b) where wheat grown under poplar boundary plantation exhibited a noticeable decline in grain yield compared to open conditions. The study reported that wheat yield reduction was more pronounced near the tree line and gradually improved with increasing distance from the trees. This spatial variation was mainly attributed to differential shading and root competition. The findings of the present study

Table 4: Yield (t/ha) of wheat under eucalypts based agroforestry system

Table 5: Yield (t/ha) of mustard under eucalypts based agroforestry system

Table 6: Green fodder yield (t/ha) of berseem under eucalypts based agroforestry system

are in conformity with the results of Ahlawat et al. (2024), who reported significant reductions in growth, physiological parameters, and yield of sorghum and barley under kadam-based agroforestry systems compared to sole cropping. They observed yield reductions of 21.16% in sorghum and 43.43% in barley, mainly due to shading and competition for moisture and nutrients. This supports the present results, indicating that tree-crop competition in agroforestry systems adversely affects intercrop productivity.

The yield of mustard was also significantly reduced under eucalypts based system. Grain yield under eucalypts was 1.30 and 1.15 t ha-1 during 2019-20 and 2020-21, respectively, compared to 1.80 and 1.70 t ha-1 under sole cropping. Similarly, stover yield was reduced from 2.40-2.30 t ha-1 in control to 2.10-1.86 t ha-1 under eucalypts. The reduction in grain yield ranged from about 28-32%, while stover yield declined by about 12-19%. The reduction in mustard yield is due to strong interspecific competition, particularly for soil moisture and nutrients, as mustard is highly sensitive to competition under limited resource conditions. Similar observations were reported by Kumar and Nandal (2004) where mustard yield declined up to 82.4% under eucalypts plantations due to severe competition effects. The decline in yield was more pronounced in the second year (2020-21), which may be due to increased canopy development and root proliferation of eucalypts trees, leading to intensified competition. The greater reduction in mustard yield observed during 2020-21 in the present study is consistent with earlier findings, as competition tends to intensify with increasing tree age due to canopy expansion and root proliferation.

The green fodder yield of berseem was significantly influenced by eucalypts based agroforestry system. The fodder yield under eucalypts was 40.8 and 35.21 t eucalypts + berseem system provided higher economic returns, indicating that agroforestry systems can remain economically viable even with some yield reduction in intercrops. Further, Sirohi et al. (2022a), who reported that fodder crops grown under tree based agroforestry systems recorded significantly lower yields than open (control) conditions, with yield improving as spacing increased. Their study showed that maximum fodder yield was obtained in wider spacing (8×3 m), while closer spacing resulted in substantial yield reduction, clearly indicating the role of tree competition.