Himachal Journal of Agricultural Research

Rajendra Prasad ¹, Anupam Sharma ¹, Sweta Sehgal ¹

Affiliations
1 Department of Agronomy, Forages and Grassland Management, College of Agriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur 171062, HP, IN

Abstract

Rice blast, caused by the fungus Magnaporthe grisea Sacc. is one of the most important rice diseases found throughout the globe. It usually damages leaves and panicles and reduces the photosynthetic area of the plant and may even lead to the death of the plant. However the disease does not develop until the favorable weather conditions prevail. Present work was undertaken to study the influence of weather parameters on rice blast in mid hill conditions of Himachal Pradesh. Field experiments were conducted during 1984 to 2012 at Palampur, located in mid hills of the Himachal Pradesh. Two varieties; Hasan Sarai and China 988 were sown on two dates (5^th and 15^th June) under upland irrigated situation. The first leaf symptoms of the disease appeared in the last week of July or the first week of August, when the mid-tillering stage synchronized with favourable weather conditions during all the years. It was observed that days with minimum temperature ≤ 20 °C, rainfall and cloud cover were important for the appearance and progress of this disease. During disease incidence, period of lower night temperature (19.1 °C), more number of days with minimum temperature ≤ 20 °C (11 days) and lower rainfall (246.6 mm) and more cloud amount (135 hrs) was observed during blast years as compared to non-blast years. It was also found that the maximum and mean temperature one week prior to disease appearance was 1.8 and 1.2 °C lower than the non-blast years indicating warmer temperature during the entire rice growing season is responsible for lower disease incidence and its further progress.

Keywords

Rice Blast, Magnaporthe Grisea, Minimum Temperature, Rainfall, Cloud Cover, Disease Incidence.

Full Text

   

Rajendra Prasad ¹, Anupam Sharma ¹

Affiliations
1 Department of Agronomy, Forages and Grassland Management, College of Agriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur - 176062, IN

Abstract

Spatial distribution of annual rainfall and rainy days, dependable rainfall and rainfall trends in Himachal Pradesh was assessed using rainfall data(1971-2014) of 40 rain gauge stations. The normal annual rainfall of Himachal Pradesh was observed to be 1267 ± 375 mm spreading over 66 rainy days. Highest annual rainfall to the tune of 1000 mm at 75% probability was noticed in 16 (with 6 located alone in the Kangra district) out of 40 rain gauge stations. An expected annual rainfall in the range of 400-600 mm was observed in mid and high hill regions of the state comprising districts of Shimla with two stations and Mandi and Kinnaur each with single station. Ten observatories indicated significant decreasing trend in rainfall while seven showed increasing trend. Increasing trend in annual rainfall was observed mainly in Shimla (Kumarsain, Rohru and Shimla) and Mandi (Karsog, Chachiot and Sarkaghat) districts. Ten stations had an increasing trend in number of annual rainy days, whereas, six had decreasing trends. The heavy rainfall event trends were non- significant at most of the stations except Pachhad and Sundernagar where it was observed to be decreasing under 75-100 mm category. In more than 100 mm category, decreasing trend at Palampur, Nurpur, Nichar and Pachhad and increasing at Malan, Berthin and Sarkaghat was observed.

Keywords

Annual Rainfall, Rainy Days, Rainfall Variability, Dependable Rainfall, Trends, Himachal Pradesh.

Full Text

   

Rajendra Prasad ¹, Anupam Sharma ², Manoj Kumar Negi ¹

Affiliations
1 Department of Agronomy, Forages and Grassland Management, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur - 176 062, IN
2 Department of Biology and Environmental Sciences, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur - 176 062, IN

Abstract

Weather extreme could be any weather parameter be it rainfall or temperature that lies outside a locale's normal range of weather intensity. The negative or adverse impact of extreme weather events could be significant whether directly or indirectly inducing stress on plant growth and performance. Enlisting extreme weather events is highly useful to ascertain their occurrence and probable impact in future. The highest single day rainfall (amount of rainfall received in 24 hours' time) was as high as 381.7 mm at Dharamshala in district Kangra, while the other stations in Himachal Pradesh received the lower single day rainfall. The longest dry spells were more frequent with higher variation during October to December which coincided with sowing of the rabi crops than March to May corresponding to grain filling and maturity of the rabi crops and flowering and fruit development stage in mango, apple and stone fruits. In the recent past, the highest recorded maximum temperature was 48.5°C at Dhaulakuan, district Sirmaur while the lowest minimum temperature was -9°C at Salooni, district Chamba. There was decline in number of cold waves, severe cold waves and total number of days with minimum temperature below normal. The occurrence of extreme weather events showed no pattern or periodicity but they continued to affect sowing, flowering, fruit development and maturity in field/ horticultural crops in the state.

Keywords

Highest Single Day Rainfall, Dry Spells, Cold Waves, Field Crops, Vegetable Crops, Horticulture Crops.

Full Text