Variations for traits associated with heat tolerance in Indian mustard (Brassica juncea L. Czern and Coss) germplasm
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was conducted to assess the variations for traits associated with heat
tolerance in Indian mustard (Brassica juncea L. Czern and Coss) germplasm at seedling and
terminal stages. Field experiment was conducted in rabi season (2017-18) at Punjab
Agricultural University, Ludhiana at two dates of sowing i.e. timely sown and late sown
conditions. Heat stress at early seedling stage lead to seedling mortality thus affecting plant
population and seed yield Terminal heat stress caused by delayed sowing shortened the
phenological durations to variable extent, significantly reduced the physiological traits like
photosynthetic pigments, SPAD value (7.2%), RWC (8%), LWR (17.2%) while increased the
RSD (23.9%), WSD (23.9%), LWL (30.4%), membrane injury (6.9%) and MDA (57.2%).
Antioxidative enzymes like SOD (40.4%), CAT (69.3%) and POX (76.7%) were upregulated
along with other biomolecules like ascorbic acid (65.4%) which increased significantly for the
protection against the late sowing/ stressful environment. Total soluble sugars decreased by
36.8%, reducing sugars by 44.7% and non-reducing sugars by 32.4% with delayed planting.
Growth parameters, yield attributes and seed yield were reduced significantly with late
sowing as compared to optimum sowing date. However, variations existed within genotypes
for different studied traits. Seed yield under late sown condition had positive and significant
correlation with siliquing duration (r= 0.600*) and reproductive phase (r= 0.558*) whereas,
negative with flowering completion (r= -0.573*) and siliqua initiation (r= -0.519*). Biological
yield had significant association with seed yield under timely sown (r= 0.774**) and late
sown (r= 0.841**) conditions. Similarly, biological yield had strong relationship with seed
yield both under timely sown (R2= 0.5985) and late sown (R2= 0.7075) conditions. Genotype
IAN was rated heat tolerant with seedling mortality ≤30%, seed yield reduction ≤30%, HTI
(≥0.5), HSI (≤1.0), YSI (≥0.71), lesser decline in the physiological traits added with
relatively higher antioxidative enzymes.
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Harmandeep Kaur (2021). Variations for traits associated with heat tolerance in Indian mustard (Brassica juncea L. Czern and Coss) germplasm (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.