CLIMATE

CLIMATE

The commercial cultivation of Citrus in the Sind area is limited to middle Sind (the districts of Hyderabad, Nawabshah and Tharparkar). The climate of this tract is quite comparable to other commercial citrus centres in the adjoining regions. In the plains of former Punjab and Frontier, citrus centres, the annual rainfall ranges from 13 to 20 inches and the relative yearly humidity from 50 to 54 percent. The highest maximum temperature is 120°F and the lowest 29°F. In the Bombay, Deccan and Khandesh sections in India, the average annual rainfall is 30 inches, the mean relative humidity 51 percent, the highest maximum temperature 110°F and the lowest minimum 36°F. Nagpur, the largest orange growing tract of India, has an annual rainfall of 44 inches and the average relative humidity 53 percent, the highest maximum temperature is I I7'F and the lowest minimum is 43°F. (Webber and Batchelor 1948). The Citrus tract of Sind _ (Vicholo Sind) has a highest maximum temperature of 110.8°F and a minimum of 47.3°F. Mean himidity is 61 percent and the annual rainfall is 7.22 inches. (Pithawala 1955).

The low temperature at which serious damage is caused to Citrus is never reached here. The area is free from prolonged cold spells (at 28°F or below) which affect adversely fruits and young shoots.

Santra, which perhaps requires a drier climate, is found to flourish in Tharusha (District Nawabshah). Though cooler weather in the northern citrus centres of West Pakistan causes unripe fruits to lose their green colour earlier compared to the Citrus centres in the Khairpur and Hyder-. abad Divisions, yet Citrus fruits are ready much earlier in these divisions if the readiness of fruits is judged from juciness in fruits and richness in flavour, due to declining acidity and increasing sugar contents. Further, cool weather seems to cause higher acidity, warmer the weather during ripening time, less acid is the fruit (Chandler 1950). Mild tropical temperature and dry period at the time of ripening seem to be well suited. Sweet oranges and grape-fruits are ready for harvest in the Hyderabad region about two months earlier and the Santras a month earlier than in the Northern Citrus centres of West Pakistan. Since the fruits in the Southern districts ripen during the warmer weather compared to the weather in the Northern districts, they remain green at the time of marketing. Blood red Malta does not develop red colour under the Sind Climate unless the winters are very severe and prolonged. However, on the whole, climatically the area is well suited to Citrus Cultivation.