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Subject: Horticulture × Author: Rahman, Naseema × End date: 2018 × Start date: 2018 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    GROWTH, YIELD AND BIOCHEMICAL COMPOSITION OF GARLIC (Allium sativum L.) VARIETIES UNDER ELEVATED REGIMES OF TEMPERATURE AND CARBON DIOXIDE CONCENTRATION
    (AAU, Jorhat, 2018-01) Rahman, Naseema; Narzary, Bhupen Dev
    A study was conducted during 2013-14, 2014-15 and 2015-16 on “Growth, yield and biochemical composition of garlic (Allium sativum L.) varieties under elevated regimes of temperature and carbon dioxide concentration” in the Department of Horticulture and Crop Physiology, Assam Agricultural University, Jorhat, Assam for screening of nine (9) germplasm/ varieties of garlic (Allium sativum L.) (seven germplasm collected from four North Eastern states along with two National varieties from DOGR, Nashik, Maharastra) in field condition; as well as to optimize the best planting month in terms of yield of selected germplasm/ varieties. The interactive results revealed that planting of garlic cloves in the month of October recorded the highest growth parameters and yield in germplasm/ varieties, viz., Bhima Omkar (V8) (11.51t ha-1) followed by Ekfutia Assam (V1) (10.03 t ha-1), Assam Local (V2) (9.43 t ha-1) and Bhima Purple (V9) (8.94 t ha-1). The four (4) screened germplasm/ varieties viz., Ekfutia Assam, Assam Local, Bhima Omkar and Bhima Purple were grown in Carbondioxide Temperature Gradient Tunnels (CTGTs) to assess the interactive effect of elevated CO2 and temperature and to identify the elite ones for future cultivation. The treatments consisted of T1 = AMB (Ambient CO2 condition and temperature condition); T2 = CTGT I (400 ppm CO2 + 20C higher than ambient temperature); T3 = CTGT II (550 ppm CO2 + 40C higher than ambient); T4 = CTGT III (700 ppm CO2 + 60C higher than ambient). The elevation of temperature and carbon-dioxide condition was maintained from planting to harvesting stage. The results revealed that improvement of some of the major morpho-physiological parameters of the germplasm/ varieties in CTGT II as compared to ambient condition viz., plant height (+9.71%), leaf number (+14.53%), LAI (+13.83%), LAD (+12.82%), relative leaf water content (+3.32%), water potential (+7.78%), photosynthesis (+13.43%). However, in CTGT III some parameters viz. stomatal conductance (-27.48%) and chlorophyll content (-21.97%) were significantly lower over ambient condition. Similarly, the biochemical parameters viz. Allicin, Proline, Ascorbic Acid content, TSS etc. showed a significantly higher value in CTGT II (Allicin content : Assam Local 5.92 mg g-1; Ekfutia Assam 5.69 mg g-1 and Bhima Omkar 4.99 mg g-1) as compared to ambient condition (Allicin : Assam Local 5.21 mg g-1, Ekfutia Assam 5.14 mg g-1, Bhima Omkar 4.54 mg g-1). A decline in chlorophyll content of leaves observed under both the CTGTs. A better status of membrane was recorded at CTGT II, as compared to CTGT III and ambient condition in terms of lower activity of MDA (Lipid peroxidation) and H2O2 content; hence a comparatively lesser reduction in membrane stability index was recorded in CTGT-II over CTGT III. Anatomical studies revealed better stomatal aperture status and anatomical modifications in CTGT II as compared to CTGT III. Better yield attributing parameters were recorded in CTGT II as compared to CTGT III and other treatments, which could be correlated to a higher per cent of reduction in bulb formation in CTGT III. Reduction of the above parameters due to high temperature was ameliorated by CO2 enrichment under CTGT II. From the above experiment, it is evident that some degree of tolerance exhibited against high temperature stress which could be attributed to higher accumulation of proline content in leaves, adjustment of anatomical features, better water status in germplasms Assam Local and Ekfutia Assam and National variety Bhima Omkar as compared to Bhima Purple under elevated carbon-dioxide and temperature condition. This indicates the differential responses of germplasm/ varieties under future climate change conditions. Thus, it may be concluded that, the present investigation extends and adds our knowledge of both crop-intrinsic and extrinsic determinants of growth and productivity. The detailed and comprehensive analysis presented in different garlic varieties and under varied and elevated climatic conditions will provide critical insights into optimal strategies for future farming of commercially and medicinally important crops like, garlic. It is anticipated that this information has the potential to benefit researchers, farmers and ultimately the consumer.