Impact of Leaf Area Index on the Absorption of Photosynthetically Active Radiation in Barley (Hordeum vulgare L.) Crop under Diverse Sowing Dates and Cultivars

Photosynthetically Active Radiation (PAR) is crucial for the physiological development of crops as it plays a key role in photosynthesis. A study was conducted at the CCS HAU Research Farm in Hisar, Haryana, during the rabi season of 2022-23 using a Split-plot design to explore the effect of Leaf Area Index (LAI) on absorbed PAR under different sowing dates and most commonly grown varieties of the region. Four barley cultivars (V1-BH 393, V2-BH 902, V3-BH 946, and V4-BH 885) were selected and grown under different sowing dates (D1 - 9th November 2022, D2 - 24th November 2022, D3 - 9th December 2022, D4 - 24th December 2022). The LAI and absorbed PAR were measured based on field observations. The findings indicated that the timely sown crop (D1) absorbed the highest PAR (86 to 95 %) and decreased absorption as sowing was delayed with the last date of sowing only absorbing 83 to 93 % of incoming PAR. D1 had more PAR absorption and LAI leading to more photosynthate accumulation and enhanced dry matter accumulation and an enlarged grain-filling period. The cultivar BH 885 absorbed more PAR followed by BH 946, BH 902 and BH 393. The results showed a clear and strong positive correlation between LAI and absorbed PAR in all the treatments. Thus, early sowing dates and BH 885 variety is recommended for semi-arid climate of Hisar region in western Haryana.