Climate and soil of Grape

Grape 

     Grape (Vitis vinifera) is a deciduous crop. Its natural habitat is temperate cli- mate. It was introduced into north India from Iran and Afghanistan in 1300 ad by the Muslim invaders; and into south India in 1832 by the Christian missionaries from France. However, grape was known in ancient India though it was not commercially cultivated until the 14th century. Wild grapes grown in Himachal Pradesh were used to prepare local wine.

Presently grape cultivation is concentrated in the peninsular India, accounting for 90% of the total area. Major grape-growing states are Maharashtra, Karnataka, Andhra Pradesh, Tamil Nadu, and the north-western region covering Punjab, Haryana, Delhi, western Uttar Pradesh, Rajasthan and Madhya Pradesh.

Climate and soil

          Temperature, humidity and light are important for grapes. Hot and dry climate is ideal. Areas with high humidity and high rainfall are not suitable. The climatic requirements of vinifera are different from those of labrusca grapes.

         Mild temperature, not exceeding 35°C in summers, impairs the fruiting of vinifera grapes, particularly, in Thompson Seedless. Higher night temperatures (above 25°C) during ripening hamper the colour development in coloured grapes. Cool nights and hot days even though congenial for coloured grapes, pink pigmentation develops in green grapes if the diurnal differences are more than 20°C during ripening.

             Under high humid conditions, the vines put forth excessive vegetative growth at the expense of fruiting. Berries do not ripen properly. Disease incidence is high. The total amount of rainfall is not the criterion, but the timing, frequency and duration of rainfall are important considerations for grape cultivation. Rains associated with cloudy weather and poor sunlight during 45–60 days after back pruning in the tropical India reduce the fruitful buds in a vine. Rainfall during flowering, and berry ripening cause enormous damage to grapes. If rains coincide with flowering, the panicles are destroyed by downy mildew. Rains during ripening cause berry cracking and rotting.

          Grapes are grown on a variety of soils in India, alluvial in north, heavy black clay in Maharashtra and north Karnataka, red loam in southern Karnataka and Tamil Nadu and very light sandy locally called ‘Chalka’ soils in Andhra Pradesh. Soil with good drainage and water-holding capacity in a pH range of 6.5–7.5 is ideally-suited for grapes. Presence of excess salts, particularly sodium and free calcium is detrimental for grapes. Vines become weak and their productive life span is reduced. The electrical conductivity of the saturated extract of soil should be less than 4mmhos/cm, its exchangeable sodium content should be less than 15%. When the soil contains more free calcium than 12%, vines suffer from iron deficiency and the soil gradually becomes sodic. High content of sodium in soil poses drainage problems and the root growth is impaired. Soils of Maharashtra, Haryana and Punjab are saline-alkali. Free calcium content is also high in soils of Maharashtra.