Adaptation and selection of crop varieties for hot arid climate of Rajasthan
Adaptation and selection of crop varieties for hot arid climate of Rajasthan
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拉贾斯坦邦炎热干旱气候作物品种的适应和选择
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
R. Bhatt
中科院分区：
文献类型：
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作者：
V. Manga;A. Jukanti;R. Bhatt
印度干旱区面积近3,17,090平方公里，其中2,46,790平方公里为炎热干旱区。大约80%的炎热干旱地区福尔斯分布在拉贾斯坦邦的11个地区。这些地区的特点是降雨量低，不稳定，变异系数高，平均最高温度高。土壤多为桑迪，有机质含量低（0.1%至0.45%），持水能力差，渗透率高，为9厘米/小时。适合干旱地区的作物是那些在干旱/干燥条件下生存和生产的作物。高粱和珍珠粟传统上主要在以上述胁迫因素的组合为特征的环境中作为玉米作物种植，这些胁迫因素对于玉米来说变得过于边际化和非生产性。高粱是一种耐旱的植物，珍珠粟比高粱更耐旱，水分利用效率更高。同样，珍珠粟比高粱更耐盐，是仅次于大麦的第二大耐盐主要谷物。珍珠粟更适合于干燥的营养缺乏的土壤，因此在高温、降雨量少、持水能力差的土壤上种植。它也有强大的深层根系和短的生命周期，并能迅速增长时，水分是可用的。因此，在年平均降水量低至250毫米的地方，它可以存活并可靠地生产少量谷物，而高粱的最低需水量为400毫米，玉米为500-600毫米。印度是珍珠粟的最大生产国，无论是在面积（930万公顷）和产量（797万吨）方面。虽然大量珍珠粟杂交种和一些自由授粉品种已被释放用于干旱地区的种植，但成熟度和耐旱性的遗传差异使一些品种更适合干旱地区。早熟品种逃避终端干旱，使这些更适合地区有极端干旱的条件，如西部拉贾斯坦邦，部分古吉拉特邦和哈里亚纳邦。除了珍珠粟，在干旱的西部拉贾斯坦邦也种植豆类。这些是蛾豆（Vigna aconitifolius），绿豆（Vigna radially），菜豆（Cyamopsis tetragonoloba），马豆（Macrotyloma uniflorum）和豇豆（Vigna unguiculata）。在这些菜豆中，瓜尔豆和马豆具有很强的耐旱性，已经确定了一些在干旱地区种植的早熟品种。由于全球变暖，气候正在发生变化，据估计，在未来100年内，地球表面空气的平均温度将上升1.4至5.8°C。这将影响农业等气候敏感部门。为了减轻气候变化的影响，需要开发耐热、早熟、耐旱、耐盐和抗病虫害的品种。珍珠粟已经具有许多这些特性，使其成为干旱地区的良好适应作物。同样，适应干旱地区恶劣农业气候条件的干旱豆类有几个早熟品种。气候变化的进一步挑战可以通过生物技术和基因工程方法开发品种来应对。
Arid region occupies nearly 3,17,090 sq km area in India, of which 2,46,790 sq km is hot arid region. About 80% of the hot arid area falls in the eleven districts of Rajasthan. These areas are characterized with low, erratic rainfall with high coefficient of variation and high mean maximum temperatures. Soils are mostly sandy with a low organic matter content (0.1 to 0.45 per cent) and with poor moisture holding capacity and high infiltration rate of 9 cm/hour. Crop plants suited to arid regions are those that survive and produce in spite of arid/dry conditions. Sorghum and pearl millet are traditionally grown as rainfed crops mostly in environments characterized by a combination of the above listed stress factors, which become too marginal and unproductive for maize. Sorghum is a drought tolerant species, and pearl millet is even more drought tolerant with higher water use efficiency than sorghum. Similarly, pearl millet is even more salt tolerant than sorghum and is the second most salinity tolerant major cereal after barley. Pearl millet is better adapted to dry nutrient deficient soils and is thus cultivated under extreme harsh conditions of high temperature, low erratic rainfall and on soils with poor water holding capacity. It also has strong deep root system and short life cycle and can grow rapidly when moisture is available. As a result, it can survive and reliably produce small quantity of grain where mean annual precipitation is as low as 250 mm as compared to minimum water requirement of 400 mm for sorghum and 500-600 mm for maize. India is the largest producer of pearl millet, both in terms of area (9.3 m ha) and production (7.97 m t). Though a large number of pearl millet hybrids and some open pollinated varieties have been released for cultivation in arid regions, genetic differences in maturity and drought tolerance make some cultivars more suitable for dry regions. Early maturing cultivars escape terminal drought, making these more suitable for regions having extreme arid conditions, like western Rajasthan, parts of Gujarat and Haryana. Besides pearl millet, legumes are also cultivated in the arid western Rajasthan. These are moth bean (Vigna aconitifolius), mung bean (Vigna radiate), cluster bean (Cyamopsis tetragonoloba), horse gram (Macrotyloma uniflorum) and cowpea (Vigna unguiculata). Of these moth bean, guar and horse gram are highly drought tolerant and a number of early maturing varieties for cultivation in the arid regions have been identified. Climate change is occurring due to global warming and it is estimated that average temperature of the air above earth’s surface would rise by 1.4 to 5.8°C over the next 100 years. This will affect climate sensitive sectors like agriculture. For mitigating the effects of climate change, there is a need to develop heat tolerant, early maturing, drought tolerant, salt tolerant and disease, and insect pest resistant varieties. Pearl millet already has many of these traits that make it a well adapted crop for arid regions. Similarly, arid legumes which are adapted the harsh agroclimatic conditions of the arid region have several early maturing varieties. Further challenges of climate change can be tackled through development of varieties through biotechnology and genetic engineering approaches.